WO2023102272A2 - Viscosity control systems for improvement to concrete, 3d print material, shotcrete, and other sculptable media - Google Patents

Abstract

In the 3D printing, or other means of building vertically without forms, using mortar or concrete materials, for the construction of buildings and other structures, problems arise with pumping or printing operations, when a preferred material viscosity, serving both purposes, cannot consistently be maintained, particularly in changing environmental conditions or during hot weather. A system, according to one or more embodiments of the present invention, is employed to measure, and also make any correction to, printing material viscosity during the 3D printing or vertical building process. The system may also provide for inline material modification, so that a more-fluid and slower-setting material can more easily be pumped to a printing system, where it can subsequently be thickened and/or accelerated for an improved printing rate and quality. According to one or more embodiments, the system can implement any necessary correction to this print material viscosity modification process, including adjustment of water proportion, automatically and continuously, without disruption to the material placement process.

Description

VISCOSITY CONTROL SYSTEMS FOR IMPROVEMENT TO CONCRETE, 3D PRINT MATERIAL, SHOTCRETE, AND OTHER SCULPTABLE MEDIA by

Michael George BUTLER

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims benefit of US Provisional Patent application Serial Number 63/286,091 , entitled “VISCOSITY CONTROL SYSTEMS FOR IMPROVED CONCRETE OR MORTAR EXTRUSION,” to Michael George BUTLER, filed December 5, 2021 . The present application is related to U.S. Patent Application S/N 62/446,444, titled “Methods and Devices to Make Zero-Slump-Pumpable Concrete,” to Michael George BUTLER, filed 01/15/2017 and “APPARATI AND SYSTEMS FOR AND METHODS OF GENERATING AND PLACING ZERO-SLUMP-PUMPABLE CONCRETE”, to Michael George BUTLER, filed 01/16/2018; and U.S. Patent Application S/N 62/793,868, titled “ADDITIVE LAYERING SYSTEMS FOR CASTCONCRETE WALLS” to Michael George BUTLER, filed 01/19/2019; and U.S. Patent Application S/N 62/830,445, titled “APPARATI TO COMPENSATE FLOW VARIATIONS OF A PISTON PUMP, PARTICULARLY ALLOWING CONSTANT RATE ROBOTIC PLACEMENT OF CONCRETE”, to Michael George BUTLER, and U.S. Patent Application S/N 62/834,923, titled “VERY RAPID CONCRETE SLIP FORMING OVER EXTENSIVE VERTICAL SURFACES WITH REMOTELY CONTROLLED AND AUTOMATED SYSTEMS” to Michael George BUTLER, filed 04/16/2019; Provisional Patent Application S/N 63300048, DIGITALLY-CONTROLLED WALL-BUILDING SYSTEMS AND METHODS, to Michael George BUTLER, filed 01/16/2022; and Provisional Patent Application S/N, 63338032, RAPIDLY-DEPLOYABLE AUTOMATED WALL-CONCRETE PLACEMENT SYSTEM, to Michael George BUTLER, filed 05/04/2022. The contents of all of these applications and patents are incorporated herein in their entirety by this reference for all purposes.

BACKGROUND

[0002] One or more aspects of the present invention pertain to the technical field of construction. More specifically, one or more aspects of the present invention pertain to the placement of cementitious materials, more particularly, various fields involving vertical-layering of the materials, such as 3D printing, very-rapid slip-forming, pneumatic-placement, or freeform-sculpting of walls, buildings, and other structures, with a concrete or mortar material.

SUMMARY

[0003] In 3D printing or additive manufacturing utilizing cementitious materials, such as mortar, concrete, grout, geopolymers, clay/lime/soil mixtures, aerated cementitious mixtures, proprietary mixtures, “hempcrete” mixtures, conglomerate waste material mixtures, et cetera, there are issues requiring continuous control of the viscosity and rheology of the printed material so that it can be reliably pumped and then also build up vertically on its own. When outdoor-site weather or temperature conditions change, or material properties change due to partial setting of cement, or new aggregate materials of differing moisture content are introduced, then a given relative dose of a viscositymodifying admixture should preferably change, in a corrective response, to maintain a proper viscosity for printing. This dose correction is most efficiently and preferably a continuously automatic process.

[0004] With some preferred cementitious materials, such as those lower in binder content, or those utilizing local native materials having greater variations in moisture and particle gradation, or those having less control of mixture consistency and setting time, and so forth, continuous control of viscosity becomes more difficult. Printing outdoors avoids the high costs of printing-then-moving building elements, or providing a sheltering structure around a given in-situ project. However, variations in weather, and especially temperature; and considering unpredictable durations of printing a given batch of concrete or mortar, there tends to be more difficulty in maintaining consistent material properties for printing. It is difficult to maintain print material properties that can be both be reliably pumped within a pressure line without stoppages or blockages, and then also 3D printed with a sufficient or preferred vertical build rate.

[0005] It should be noted that some proprietary printable media is more forgiving than are more ordinary concrete or mortars (such as those that are Portland-cement- based); and such proprietary media can be of materials more suited to demands of 3D printing. The reasons for this can be the media having a combination of having a lower- density and a higher amount of polymer material - that is chosen for more helpful rheology parameters. However, these specialty materials - even from waste sources - are going to be more expensive (particularly when considering shipping costs) than locally-sourced or native materials using a low-cost binder such as Portland cement. One goal of some embodiments of the present invention is to maximize the utility of a lower-cost, locally-sourced materials, despite them having variable inherent properties and moisture contents.

[0006] One or more embodiments of the present invention provide preferable and more efficient methods and apparatus to avoid interruptions in pumping operations, and to have a more rapid vertical buildability, while allow a more robust reliability in printability in variable weather, when using a less expensive print material. The preferred viscosity for a cementitious material to be 3D printed is something that correlates to a very low slump, according to ASTM C143. For 3D printing, for example, an ideal slump may range from between about 2” (50mm) and zero, but this depends upon many factors including mix design, temperature, placement rate, time period between adjacent print filaments, and what factors determine the slump measurement. If a zero slump is due to a setting action of cement, then this slump is far too low for printing, for example, but if it is due to inclusion of thickeners introduced to the cementitious material, then it could be appropriate. As there are so many variables affecting what slump (viscosity) is best for various placement applications, the relevant issue is slump (viscosity) relative to another slump that works in for given conditions. The purpose of the present invention is not to establish what determines an ideal viscosity for a given application - this is up to the User - but to take measurements of viscosity, temperature, and other relevant properties, and then be able to make corrections as needed or preferred, manually or automated, in order to get back to the ideal material properties selected for material placement.

[0007] The viscosity measurement can have different significance depending upon material temperature. A relatively high viscosity, but with a relatively low temperature, indicates that the viscosity is mostly due to less water or more thickening admixture; whereas with relatively high temperature, it indicates that the material is setting up or is closer to setting up. The most beneficial viscosity correction for each of these temperature conditions will differ.

[0008] The fastest, most reliable vertical build, with the least risk of pump line blockages, is made possible by modifying the print material, within the pump line, prior to extrusion. This allows for a more fluid, lower viscosity material to be pumped, and then the extrusion for 3D printing can be made with a thicker material that prints better and faster. This method also allows the initial pumped material to include a retarding agent at a high dose - that would normally prevent printability; but with inclusion of a subsequent inline modification, it is possible to “reawaken” a “dormant” print material. This strategy greatly reduces the risk of costly line blockages, even after printing delays in the heat. To include a thickener, or a combination of thickener and set-accelerator, intermixed inline before extruding, allows more reliable printing and a more rapid vertical buildup of the print material. The present invention improves this process by continuously monitoring, then allowing automatic-implementation of corrections to, the printed material. [0009] With this in-process thickening, each pass of the printer head can then extrude a taller filament. Presently for 3D printing (without side-trowel devices), an 18mm vertical dimension is a common practical maximum height for a 50mm-wide filament width, using a Portland-cement-based normal-weight-sand mortar, the most common material for this process presently. By using an in-process viscosity modification system, print filaments of 25mm to 50mm high are practical for the same width; that is, producing a filament cross-section having a height that is up to that of its width, using a Portland-cement-based mortar or the equivalent. When side-trowel devices are employed, this method (which can now be defined as digital slip-forming) will then allow a filament to be greater in height than width, using a Portland-cement- based mortar, or the equivalent. So, this improvement allows a more-than-doubling of the build rate, for a given printer-head speed, without any change to mortar composition, other than in-process thickening. Then, by utilizing viscosity corrections provided by this viscosity control system, allow the improved build rate to be maintained consistently, though changes in relative humidity, temperature, sand moisture content, mortar w/c ratio, and other variables. Subsequent batches of mortar made onsite, whether pre-packaged or made from lower-cost raw materials onsite, can all be made to extrude the same as previous batches, or at an improved rate, according to User preference, because of the various viscosity detection and correction systems disclosed.

[0010] This viscosity control can be continuous, effectively immediate, and without any interruption or delay to the 3D printing process, so avoiding major catastrophes and also minor but irritating disruptions - such as otherwise needing to perform material slump tests, etc. The viscosity corrections determined by the system can be passive or informative, where user intervention makes a needed viscosity correction; or the system can actively implement needed corrections, so that an improved print material viscosity can be maintained automatically and continuously. The automated correction system can be omitted if the User instead makes chosen dose rate corrections, based on information provided by the any one of the several viscosity determination systems disclosed in the present invention. [0011] The term “print material” is utilized here for convenience, generally meaning to include any material mixture that is an aggregate of particles combined with a binding material, that will harden in place, even though 3D printing may not be taking place - more generally this is anytime one is building a vertical shape with material that will harden in place. The “print material” term stems from the very acute material-control problems with 3D printing when using site-sourced sand and other aggregates, those having a variable moisture content, or when printing outside with highly variable weather conditions, etc. The binder for such a material is typically a hydraulically-setting cement. An aggregate of particles within the material is referred to as “aggregate”; this can mean any solid particles such as sand or rock or fly ash, or bits of foam or recycled plastic or rubber, or air bubbles -in the case of an aerated mix. In any case, there is a preferred viscosity (and rheology) for a vertical build of the material, and a determination can be made as to what the preferred viscosity (and rheology) is for a given vertical build. This system can maintain that viscosity (and rheology), by adding, subtracting, or maintaining a present proportional dose of a viscosity modifying (rheology modifying) admix. This improved control of a print material is not limited to hydraulically-setting materials however, the same method and process is suitable for entirely synthetic binders; or adobe, which can be modified with an admix of water-absorbing solids, such as risk husks; or lime-based (calcium hydroxide) mortar, which can be modified with other thickening-solids or agents, or by injection of a gas, such as carbon dioxide. In these cases, the print material properties are measured, and then modified (or not) according to those measurements. The modification can be increasing or reducing material viscosity (and rheology), or simply maintaining present viscosity (and rheology). This is also a viscosity (and rheology) monitoring method, in place to maintain beneficial properties of a print material, even when no change is needed, by providing a consistent proportional dose of modifying admix.

[0012] For large-scale 3D printing, a common print material is a portland-cement (or other type of cement) based “mortar”, or if coarser aggregates are included, then the term “concrete” is most often used. These embodiments are also equally effective for any general construction using concrete having vertical or sloped surfaces. A particularly well-suited example is free-form landscape walls, that will be sculpted into a faux stone appearance while the concrete or mortar is still workable; the practice often known as vertical artistic concrete, or by similar terms. The term “admix” used herein is shorthand for an admixture or additive to the concrete, in this case it is one that acts as a thickening agent. The admix can include set accelerators or other components, such as those creating a false-set, or water-absorbing solids, or curing agents, or lubricating materials, or development of a gel structuration within the water component, etc, to modify the print material facilitate the 3D printing process. A retarder can also be included in the admix or dosed before the introduction of thickening admix. The term “viscosity” is generally used to indicate a resistance of material to flow; though in this case “viscosity” refers to material dynamic yield stress, plastic viscosity, and static yield as important indicators of printability factors (which collectively define a material’s rheology), as these factors affect the visual and structural quality, speed of printing, and allowable vertical build rate (according to a Bingham model of mortar/concrete-like materials). “Viscosity” is used herein meaning to describe the changes in print material properties that allow an increased rate of vertical buildability. When a material is herein referred to as “modified” this is to indicate inclusion of the admix for (primarily) viscosity modification purposes, and is not to mean the common usage of a “mortar/concrete- having-an-acrylic-modifier”; even though there is overlap in these concepts, in that many acrylics will thicken when introduced to the high pH of Portland cement; so these types of acrylic modifiers can serve as a useful component of a thickening admix.

[0013] The method of placing the print material is independent of the present invention. The term “3D printing” is used because of general familiarity with that term and serves as an appropriate application of this technology - one where the need for this improvement is acute. However, the active viscosity control and/or correction can be used to facilitate other methods of material placement, such as rapid vertical slip forming of concrete, or application of aircrete (aerated cement mixture) stacked against an existing vertical surface, for fireproofing, or for conventional concrete placement where a reduction of form pressure is sought, et cetera. These methods can be categorized as “additive manufacturing” or when digitally controlled, and more generally as an “additive layering” process to indicate a vertical buildup of the material where there are not pre-situated forming elements present to contain the material or to define finished geometry, whether the material placement is manually or digitally controlled. A rapid-vertical slip-forming such has been developed by the preset inventor, is distinguished from conventional vertical slip-forming, by the attainable vertical build rate. Conventional slip-forming can go vertically at rates in the range of several feet per 24 hours, whereas rapid-vertical slip-forming can go vertically at up to several feet in a few minutes - because of the inline modification to the concrete material. The present invention provides improvement to all such methods, here characterized as “additive layering,” even though the term “3D printing” is utilized for convenience of recognition, and as it this method is clearly in need of viscosity control. All of these construction methods can benefit from the inclusion of in-process modification of the print material, by intermixing a thickening admix, and using active viscosity control.

[0014] With viscosity control, any given print material viscosity can be compared against the vertical build performance of another material’s properties, as it is relative viscosity and/or relative rheology values that are most pertinent. User judgement will ultimately be the means to determine the ideal material properties for a given project. This system will provide a continuous stream of information in order to help make that judgement, and can also provide automatic viscosity corrections to unwanted changes in viscosity, such as when an older batch of print material grows stiffer, or when some fresh more-fluid material of a new print material batch is introduced into a 3D printing system.

[0015] The determination of material properties of a Bingham plastic, such as mortar or concrete, using a rotating vane rheometer, is a known science. There are such products available for automated determination of concrete material static yield stress, dynamic yield stress, and plastic viscosity by applying rotating vanes at various rotation rates, and measure torque resistance, in order to determine these properties. In this case, a concrete sample is taken from the production process, or prepared for testing purposes, and is then placed into a container of specific design for the vane testing. These data are used to determine whether changes to the concrete mix design are necessary or preferred for a given application. In the case of the present invention, a device utilizing this same principle is applied to a print material within a given continuous 3D printing process, but without any delay or diversion of material for testing purposes. Then, the results are utilized to make viscosity corrections during the printing process. The print material viscosity can be continuously and automatically corrected to meet a preferred value, during a 3D printing process, so that printing production can be optimized.

[0016] As the rheometer measures both static yield and plastic viscosity (dynamic viscosity), it allows a determination of vertical build robustness beyond a single static yield point that is measurable in a slump test. In other words, two print materials of the same density can have the same yield point (the same slump) and can be stacked vertically to the same height without collapse, but the one having a lower plastic viscosity (shear thinning) will extrude more easily and will have more robustness in printability after changes in other variables such, as temperature and print material age. Also, a print material with lower plastic yield will bond better with previous layers already extruded, and will be easier to trowel to a smooth surface (simultaneously with printing or post printing) with other factors held constant. Similarly, a print material that has been dosed with a retarding agent, then induced to a false set with admix, will also be more easily worked and have improved interlayer bonding, with previously-printed and subsequently-printed filaments of print material. The simplest way to implement a lower plastic viscosity without changing yield point, is to utilize a more fluid print material along with an increased dose of admix. Or, one can use an admix composition that utilizes a (repeatable) false set. In both cases, for improvement of printability, the initial print material fluidity cannot be increased by a very high dose of a contemporary high range water reducer, as the effect from this is to reduce plastic viscosity (shear thinning) for a given yield point; in other words, pumping becomes more difficult for a given slump. [0017] The testing and modifications to print material to improve printability robustness should preferably be undertaken prior to beginning a printing operation. For this, print material can first be manually placed in container, so that this independent measurement system can measure pumpability before beginning a print material delivery process (by pump). Ideally, once the robustness of favorable print material properties has been optimized, the print material delivery and printing process can then be initiated. The viscosity control system of the present invention can then autonomously measure and correct the print material viscosity, to remain optimal for improved uninterrupted printing.

[0018] The vane devices of the present invention would vary from previously existing testing devices in that print material for printing is of a higher viscosity (lower slump) than the existing vane devices are generally designed for. Standard test vanes typically measure shear force of concrete between the vane outer edges and a ribbed container surface. The present devices require more power for a given vane exposure to torsionresisting material, because of the higher shear strength of thickened 3D printing print material, and/or use of fewer vane blades than the 4 commonly found on portable vane rheometers, or use vanes that that have openings, such as those on paddle blades of mortar mixers. For very stiff mixes, a vane that is only of a heavy wire frame can be utilized, where resistance to flow is only of the wire elements pushing through the print material, rather than a set of solid vanes twisting the mass of print material within a container. For this design, the container surface is less loaded with shear forces relative to the print material viscosity, and so the need for projections on its surface - to prevent the spinning of the entire print material mass - is reduced.

[0019] If the thickening admix is reactive to a common element of any of the variations of printable materials, then it can modify any of those, for improved printing. For example, a water-reactive thickener can be successfully applied to improve the 3D printing of any printable media that is water-based. Where the thickening is created by a false-set of any given hydraulically-setting media, it must be a repeatable false-set, or at least one that can be created and/or maintained after the agitation involved in intermixing the admix. For example, admix compositions disclosed in the first patent application referenced will induce the effect of a false set, repeatedly. Also disclosed is a means to automatically adjust the amount of the water component to change viscosity of the mixture, in lieu of, or in conjunction, with adjustment of admix. Water adjustment can adjust for changing/drying conditions and it can make use of well-known methods of adjusting the water content in concrete; however, it offers a more limited range of adjustment in terms of material pumpability and stackability.

[0020] An assumption here is that the material is sufficiently pumpable at the outset, and that it also has properties allowing whatever placement process used. For example, a 3D print material generally needs to have enough very fine particles in it to allow extrusion in neat layers. Given this, the material pumping pressure is another measurement tool that can be used to determine material properties, but only in a very limited way. The problem being that a high pumping pressure may just mean that you are about to have a blocked line, so it is not a very useful material measurement tool. The cause of a blocked line is not enough lubrication. This can be from not enough water, not enough very fines, or a material that is setting up. So if a pump line pressure is getting too high, at least one of these problems needs to be solved before more material gets into the pump. With this inline modification, there can be more water, if desired, and a retarder can stop the setting up problem, because the admix can entirely compensate for these effects. The amount of very fines can be reduced somewhat, but a fines-deficient material cannot be entirely compensated for with admix.

[0021] The systems disclosed can regulate the additive-layering process, by providing a material that can have consistent properties for placement, under variable conditions, but means of an active or passive system that can make corrections to the material properties, during the additive-layering process, and before the material is placed. This allows the additive-layering process to benefit from using a material having more consistent properties through changing environmental conditions.

[0022] BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a schematic diagram categorizing relevant monitoring and correction systems.

Figures 2A - 2G show variations of viscosity measurement and monitoring systems. Figure 2A shows components of an active correction system, and an independent viscosity measurement and monitoring system.

Figure 2B shows a viscosity measurement system that is integral with the extrusion system.

Figure 2C shows an independent viscosity measurement system concentric with the extrusion system.

Figure 2D shows an ultrasound viscosity measurement system that includes an active inline mixer.

Figure 2E shows an ultrasound viscosity measurement located post-extrusion-process.

Figure 2F shows a system where material modification and ultrasound measurement are post extrusion.

Figure 2G shows a viscosity measurement system using a pressure measurement ram. Figures 3 and 4 show specifics of a concentric vane viscosity measurement and monitoring system.

Figures 5 and 6 show specifics of a multiple-independent vane-set viscosity measurement and monitoring system.

Figures 7A and 7B show an assembly for shielding a modified ultrasound testing device. Figure 8 shows modifications to a mini volumetric mixing system so that it can be used to produce a zero-slump concrete, and a cradle that allows it to build walls directly. Figure 9 shows modifications to a volumetric mixing system so that it can produce a zero-slump concrete.

Figure 10 shows a logic flow chart for writing code for a viscosity compensating system that controls a dose of thickening admix, with a list of User selected variables, and an example of viscosity term relative values.

Figure 11 shows a logic flow chart for writing code for a viscosity compensating system that controls the dose of water in a printable mix or concrete, with a list of User selected variables, and an example of viscosity term relative values. [0023] Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention. Reference numerals are meant to be interchangeable between drawing figures, so that a reference numeral not referred to in a given figure description will be described elsewhere.

[0024] DESCRIPTION

[0025] Various embodiments of the present invention may include any of the described features, alone or in combination. Other features and/or benefits of this disclosure will be apparent from the following description. The order of execution or performance of the operations or the processes in embodiments of the invention illustrated and described herein is not essential, unless otherwise specified. That is, the operations or the processes may be performed in any order, unless otherwise specified, and embodiments of the invention may include additional or fewer operations or processes than those disclosed herein. For example, it is contemplated that executing or performing a particular operation or process before, simultaneously with, contemporaneously with, or after another operation or process is within the scope of aspects of the invention.

[0026] The various elements of any of these devices disclosed herein can advantageously be combined with other devices in many different permutations. Generally, for the present disclosure, only a single example of each feature is given, and any of the other combinations of the features is not also shown, as it is typically apparent that these other combinations of the features can be made by persons of ordinary skill in the art in view of the present specification.

[0027] As will be understood by a person skilled in the art, aspects of the present invention may be embodied as a system, method, a computer program product, or combinations thereof. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as an “apparatus”, a "circuit," a "module" or a "system." Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more non-transitory computer readable medium(s) having computer readable program code embodied, e.g., stored, thereon.

[0028] Any combination of one or more non-transitory computer readable mediums may be utilized. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0029] Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java(TM), Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language, such as .net framework and Microsoft Corporation programming languages and databases, such as HTML5, Android Mobile applications and Apple Corporation iOS mobile applications, or similar programming languages. The program code may execute entirely on a local computer, partly on the local computer, as a stand-alone software package, partly on the local computer and partly on a remote computer, or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the local computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). The program code may reside on remote servers and software networks such as for cloud computing such as, but not limited to, Amazon Web Services, Google cloud etc. Mobile applications of the program code may also be available for download from services such as Apple App store and Google play.

[0030] Aspects of the present invention are described below with reference to flowchart illustrations and/or block diagrams of methods, processes, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions which execute via the processor of the computer, other programmable data processing apparatus, or other devices enable implementation of the functions/acts specified in the flowchart and/or block diagram block or blocks.

[0031] These computer program instructions may also be stored in a non-transitory computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.

[0032] The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

Figure 1

[0033] Figure 1 shows a simplified schematic diagram defines key elements according to one or more embodiments of the present invention. Similarly, numerous other embodiments are described in Figures 2A through 2G, following. Any necessary power source to any element requiring such is not shown for clarity, and is assumed, for all of the drawings provided.

[0034] In the case of construction 3D printing methods, it is common to process material in two separate but related material movement systems. A print material delivery system 4 can be of many variations; in this case it is providing material for an extrusion control system 8. Material delivery system 4 is commonly where print material is delivered to an extruder 18, within flow of print material 3. The conveyance of print material can be by any imaginable means, as needed to provide print material for the extrusion control system 8, including humans with shovels. Embodiments disclosed involve pressurized pumping as a means of material delivery system, where modification by intermixing a thickening admixture to delivered material can be accomplished within that pressurized conduit, though this modification can also be by means of open channel flow with intermixing by auger, for example, or the intermixing can occur within the extrusion control system 8, by various means. Extrusion control system 8 controls the 3D printing path of travel according to a 3D digital model made compatible with the print process at hand, and it extrudes material a rate relative to the rate of travel of the printing sequence. Commonly, but not universally, the two systems then interface at a reservoir of print material, withheld for extrusion, in a container 6. Delivery system 4 is tasked with supplying print material to the container at a volume sufficient for the functioning of extrusion system 8, which is tasked with a controlled extrusion of the material for 3D printing. A print material extruder 18 is moved by system 8, along a controlled path of travel and at a controlled rate, placing layers of a print material filament 19, that layer create a given building or structure. The control of inline modification disclosed herein clearly allows improvements to the printing process, and also allows improvement to any other concrete placement process, by allowing vertical build without forms, or earlier removal of forms, or faster placement of shotcrete, etc. “Viscosity” is the simplistic term used here as shorthand for print material or concrete having a rheology favorable to printing, early form removal, shotcrete performance, etc. This favorable rheology is discussed further below. Also, initial set of the material will increase viscosity, and so this same dose correction works for use of a set-accelerator in lieu of, or in combination with, a rheology modifier. The viscosity of the print material is measurable, and the assumption here is that a preferred or favorable or ideal viscosity is determinable. This determination can be by a visual assessment, or by placing material to see how it stacks, or by empirical data about what measured viscosity and/or rheology has worked best previously. What is new here is that the uncontrollable variables to print material behavior can now be compensated by adjusting a relative-proportional-dosing of a modifying admix. This compensation can be manually determined and executed, or a partially or fully automated system.

[0035] As print material is delivered to container 6 via system 3, this provides opportunity to proportionally intermix a thickening agent, continuously proportional to the print material pumping rate of system 4, according to methods and materials according to the first patent application referenced above, or by other methods. The thickening admix dosing rate is then proportional to the print material delivery system 4 pump rate. A viscosity control system 1 serves the purpose of measuring the viscosity of the print material, in this case the material held within container 6, and based upon this measurement, system 1 can also modify a proportional dose of a thickening admixture, based upon viscosity measurement taken. Subsequent measurement taken will provide information for any further dose modification, based upon a viscosity target value. More specifically, viscosity data is acquired by a viscosity monitoring system 10, which sends that data to an active correction system 12. System 12 is capable of determining corrective information, based upon a viscosity determination relative value to a user- determined target value, and sending corrective modification to a previous admix dose proportion. Material delivery system 4 delivers both print material, which includes the water component, and admix at an initial proportional rate 37. System 12 sends proportional correction to the thickening admix initial proportional rate, creating a modified proportional rate of admix, or delivered admix flow 39. This dose of admix can be delivered in proportional flow to a material flow of a volumetric system, or it can be a proportion of a discrete batch of material, such as a known amount or print material withheld in reservoir 6. In an alternative to admix adjustment, an embodiment of the system can change the amount of the water component in the mixture, by access to the control of a connection to the water metering system of the material delivery system 4, a well-known practice in 3D printing an volumetrically-produced concrete. In this way the material can be a multiple component system which can include water and everything else; or water, admix, and everything else.

[0036] System 10 can continuously or intermittently acquire viscosity information, and send that to system 12; where system 12 is then adjusting thickening admix proportion, in order to continuously or intermittently correct the print material viscosity, so allowing improved 3D printing, etc. As environmental conditions or mix materials or water content or other variables change during printing operations, the continuous viscosity control system 1 will be able to provide a print material having consistent print properties.

[0037] Alternatively, the extrusion control system 8 can be used for intermixing admixture, for 3D print systems not having a reservoir of print material, or for cases of dosing admix after the print material is withheld in container 6. This can be a variation of the case where the admix dose monitoring system is based upon the extrusion resistance, an embodiment described further below. In these cases, the extrusion pumping rate can be the relevant pumping rate for relative dose rate of an admix. For other methods of cementitious material placement, such as slip-forming concrete using a pump, and other method sequences, the material placement by that pump can be that relevant to a proportional dosing of admix. In all cases, a flow rate of concrete or print material must be known with enough precision in order to determine an appropriate flow rate for a given admix. A User can always override an active control system, and those choices are indicated below. Preferably the User will modify a target viscosity value, then controlled by the active system, based upon real time best printing performance under varying conditions.

[0038] What is essential is that Figure 1 is a viscosity monitoring and control system 1 that can be used with any method of placement of concrete or print material placed with a pump, regardless whether system 4 or system 8 or whatever system is used for concrete or material placement. Viscosity control system 1 has two essential parts, a viscosity monitoring system 10 and an active correction system 12. There are many viable embodiments for system 10, with several of them depicted here. The correction system 12 can range from that of simple user inputs based upon visual information provided by system 10 (or variations of that system), to an automatically-implemented active-system that continuous adjusts admix dose rate to meet preferred viscosity values, or printing results, as predetermined and/or updated by User. The dose rate can be proportional to a volumetric system of producing concrete or print material, or it can be a dosed proportion of a discrete batch of concrete or print material.

[0039] Alternatively to adjusting admix ratio to change viscosity of print material, and where a volumetric print material-producing system is used to produce that material for feeding the print material delivery system 4; system 10 can be used to determine any necessary or beneficial adjustments to the water ratio of the volumetric mixing process, and system 12 can be used automatically make those adjustments to that water ratio to change print material viscosity. For any type of print material delivery system, the amount of water can be modified, and the temperature of the material can be changed by use of an internal cooling system, etc. These are all now new concepts, in that in now the new system 10 can be used to monitor conditions and determine if change is necessary, and a new system 12 (or User) can enact the change. It is important to understand that system 12 can and will vary considerably according to proprietary hardware, data acquisition technology, and software. For example, concrete placement temperature sensors are now commonly wirelessly transmitting to cell phones, with this information integrated within an application for determination of when forms can be removed, etc. These types of systems can be employed as part of system 12, and there may be multiple systems, such as for vane-measured viscosity, ultrasound- measured viscosity, material temperature, material humidity, extrusion force, etc. Any of these systems can be utilized individually, or an array of the different systems can be combined into a multiple-factor system 12 to provide more comprehensive information for determination of what corrective actions are most beneficial for mixture - for both material printing performance, and degree of bonding to previously-printed layers. Likewise for more conventional means of concrete placement.

Figure 2A

[0040] Elements of an independent viscosity monitoring system embodiment 10A, and of a simplified representation of an active correction system 12, are identified. [0041] In this embodiment, correction system 12 makes changes to admix relative proportion, based upon input from viscosity measurement of print material by system 10A, or by User input. A source of a thickening admixture 34 is made available to be delivered by a pump 36, having a pump rate controller 38. These can all be elements of an embodiment of the patent application referenced previously. Print material delivery system 4 delivers the flow of print material 3 through a conduit 5, then through inline mixer 24, and then through an inlet 22 into container 6. The thickening admix pumping rate is initially set proportionally to the print material pumping rate, per the print material delivery system 4, according to an initial estimate of a preferred admix relative proportion. The admix dose rate could remain at this same proportion to the print material pump rate (though shut off when the print material pumping is shut off), but this admix proportion (thickener dose pump rate) is preferably corrected or modified as needed or preferred, according to changing conditions or material states, or changes in printing preference, with active correction system 12. [0042] For other material pumping control methods described above and below, the print material proportional flow rate, on which the admix flow rate is based, may be on a system other than the material delivery system 4. For example, admix base flow rate can be proportional to extrusion flow rate, or concrete pumping rate, and then these devices would be linked to admix pump control 38.

[0043] The thickening admix 34 is dosed via a line of admix flow 39, into the inline mixer 24, of the patent application referenced, where print material flow 3, supplied by system 4, is intermixed with admix before reaching inlet 22 of container 6. The print material is extruded through a print material extruder 18, which can be a progressive cavity pump system, or the like, powered by a motor 20. Extruder must be suitable for the size aggregates to be used with print material.

[0044] For this embodiment, an independent viscosity monitoring system 10A is given instructions to conduct rotational vane testing, by connection with a CPU, though a device control system 29 or the like, and such operational software. This can send a signal, 31 A in this case, to initiate testing. In the general case, signal 31 can be generated by matching vane-driving software, such as that developed by entities listed below. Based on rotational torque and rotation speed monitoring, disclosed more thoroughly below, system 10A then generates viscosity data based, on rotational resistances of the print material withheld in the container 6, and sends that information, shown as a signal 41 A in this case, to a data acquisition unit 33, for analysis by the CPU. The CPU can simply display the result for decision making by User, or CPU can be programmed to send corrective action to the device control system 29, or another device control independent of that sending control information to system 10A. The signals 31 A and 41 A are specific to the vane system in 10A in this case, and so are given the “A” designation. DAU 33 preferably has multiple channels, for accepting input of various data for CPU analysis. CPU software (such as the example given below) can calculate data significance and then send corrected dose rate instruction to the device control system 29, or if controller 38 is digital capable, then digital information can be sent directly to it. Or other corrective measures can be taken as described herein. For a passive response system, CPU can simply display the data, to inform User decisions to manually modify dose rate, to preference. User input can be via the CPU, as in a semi-autonomous system, or the dose rate modification can be made independently of the CPU.

[0045] System 10A determines print material viscosity with a mixing vane 26 (or multiple mixing vanes) that is rotated by a drive 40A, per a series of rotational-speed- torsion tests, which measure he shear resistance of the print material. For testing purposes, rotational speeds can range from about 0.02 to over 1 rotation per second, or faster, with each held at an interval duration long enough to determine a stable result, such as 5 seconds, though this can vary. For determination of static yield point only, one very slow rotation test usually needs to be performed. For determination of plastic viscosity and yield stress, this testing generally starts at the highest rotational speed selected, and ends at the lowest, of at least 3 tests. According to Bingham theory, each test determines a point on a line (of plastic viscosity slope), which can be extrapolated back to determine yield stress- one primary indication of how rapidly the print material can be 3D printed, or how high built up vertically in a given time period, without slumping.

[0046] The direct (static) yield point test of undisturbed print material is possible, and without incurring a waiting time of at least 10 minutes without print material disruption, as recommended by some; in that the addition of admix can provide an immediate gelling action to the print material, and the process of printing is most vulnerable immediately after extrusion, not 10 minutes after (when by then a set accelerator may have already taken some effect), and so a static test is valid for evaluation this property (for purposes of printability) immediately after the print material has been sufficiently intermixed with admix. There is a range of rheological properties for a given material where both pumping and vertical build are both favorable; this is referred to as a preferred range of viscosity (where a target viscosity is at or near the middle of this range), which is an over simplification of the more complex rheology and cement early- setting factors, but the simplified terminology is used herein for convenience of explanation of the material monitoring and modification system. [0047] The drive 40 can be of many configurations, version 40A in this case. Most commonly this case would be an electronically commutated motor (brushless motor) which is including an electronic controller; in that these devices include a motor 28 and a controller 30 that knows motor rotation speed and power consumption; if not also shaft rotation location, as is the case with stepper or servo motors. Such motors can provide torque feedback by various electronic means, and can have a specific “shaft feedback device,” a version of a rotary encoder, for transmitting such data to a controller or CPU for analysis. The compatibility of the device control system, or a need for that system with a given motor/drive system is up to the system builder.

[0048] Instruction data needs to be determined for the drive 40A, in order to start the testing process. This is sequential instruction on driven rotational speeds and durations, that can be generated by the User, and sent via the CPU, and control system 29, if needed. Then, feedback data, including current draw (corrected for efficiency), actual voltage, and vane rotation speed, are returned to the data acquisition unit 33 for digital processing by CPU. This communication and data processing circuitry, with operational software, has been developed by the International Center for Aggregate Research (ICAR) at the University of Texas, and for the ICAR Plus Rheometer, manufactured and sold by Germann Instruments, Emdrupvej 102, DK-2400 Copenhagen, Denmark.

[0049] Herein referenced is this report on rheometers for concrete and mortar, by Patrice Estelle, Christophe Lanos: High torque vane rheometer for concrete: principle and validation from rheological measurements. Applied Rheology, Kerschensteiner Verlag, 2012, 22, pp.12881 .10.3933/ApplRheol-22-12881 . hal-00673458. This study investigated a higher torque device than the ICAR device, and it found that the higher torque device successfully evaluates varied mixes and correlates to standardized slump test values for concretes and mortars, as well as evaluating dynamic viscosities. The size and surface area of the vane 26, relative to driving power, can be that of this report; however, as the viscosity is generally higher in this case, it is likely that the preferred relative vane is smaller, to even less than half the relative size of the report.

[0050] It should be noted that the processes adopted for rheology testing according to established standardized values for concrete are not necessary for the present invention. The purpose of this testing is for a determination of improved or diminished printability of a given print material - so that appropriate corrections can be made, and so this testing processes can vary according to achievement of this goal, and even approximate information will assist in this determination. Print material withheld in the container 6, or within the pumping lines, holds the information needed to determine its printability: What rate it can be printed, and what available measures can be implemented to improve printability rate and quality. With measurements of iterations of print material modification, the present invention can also evaluate what can be done to make the print material more robust for more reliable printability under changing conditions, discussed below. The relevant information is primarily relative values to what is already printing well or not .

[0051] The print material properties are determined by measurement of torque resistance at various rotational speeds. For any motor where the efficiency (useful power vs supplied power) is known (considering all relevant frictional components and gearings), then the rotationally-resisting torque (of the print material) can be determined by measurement of power consumption by the motor at a given rotational speed of the vane:

Resisting Torque = Power Draw * Motor Efficiency I Rotational Speed of Vanes

By this method, most any variable-speed electric motor could serve as a form of drive 40, if the power efficiency, current draw, and vane rotational speed (if different from motor speed by gearing) are all knowable, and in a format that is useful for feedback to a CPU or at least as a display for User. This principle could apply to most of the presently disclosed embodiments, where only a relative change in viscosity is needed. A brushless motor with the associated controller will generate this information as part of normal operation, and it is a known art to link this to computing systems. If unknown factors, index errors, and mixing container geometry, prevent determination of absolute viscosity properties of the print material according to established standards, but only relative material property determinations are determinable (compared to other such print materials of the same process), then the method is still entirely viable. This is because a given print material can be compared to a previous print material, for determination of corrections to admix dose rate. In reality, such empirical methods would be employed, even when absolute material properties are known, because the bottom line is improved printability of a given print material, or more successful placement of rapidly-slip-formed concrete, as determined by the User.

[0052] For very reliable and precise torque measurement one can use a specific shaft torque measurement device 32, located between the motor 28 and the vane 26. Known as a rotary torque sensor or a rotary torque transducer, these devices can measure both torque rotational speed. The devices utilize strain gauges or coil excitation, et cetera, along with rotary encoders and the like, to generate data. The Mountz Corporation, 1080 N. 11th St., San Jose, CA, 95112, manufactures suitable torque sensor systems, employed for purposes such as testing fastener break-off strengths. These can be employed for this purpose. This is the version of this embodiment indicated in Figure 2A, where the device 32 is shown sending a signal back to the DAU 33 and CPU. If device 32 is not present, this information can be sent from the controller 30, or as otherwise described herein. For a torque sensor that measures only torque, that data can be combined with rotary speed data generated by the motor controller.

[0053] A link between the print material delivery system 4 and the extrusion control system 18 is a means of determining a print material level 14 in container 6, such as the use of a rangefinder 16. Such a device is presently employed in 3D printers for purposes of maintaining sufficient print material for printing operations. This is also relevant to measurement of torque in that vane 26 must obviously be fully submerged in print material to accurately measure print material properties. It is necessary to have the rangefinder also send print material level data to CPU via DAU, or the equivalent, so that torque measurements can be invalidated or halted until system 4 has restored a sufficient level of mortar to container 6. As vane become more deeply submerged in mortar, there will be some artificial increase in viscosity readings. A correction for such readings varies according to general material properties and container geometry, and can be determined by changing vane depth without changing other variables, and then this correction can be applied, according to rangefinder readings during a print process, so that print material depth changes can be compensated.

[0054] An optional nozzle 45 is shown below extruder 18, as may be helpful to the 3D printing process. In this case, container 6 includes an internal temperature sensor 13 that sends a temperature signal 15 to data acquisition unit 33, or to an electronic system specific to the sensor 13. An example for sensor 13 is the “Concrete sensor HCS TH1 #2300652” made by Hilti, North American headquarters at 7250 Dallas Pkwy #1000, Plano, TX 75024. This unit is made for leaving in place to monitor conventional concrete placements, so it is capable of determining material temperature, strength (as concrete is hardening), and humidity. Some product data on measurement: Strength and temperature: every 15 minutes for the first 60 days, Relative humidity: every 6 hours; Complies with ASTM C1074; Bluetooth range: 100 ft; Temperature range: -40 °F - 185 °F; Max depths; < 6 inches (15 cm). The monitoring of flowing material for improved 3D printing is a new and different use for these types of devices, and a capacity such as “strength” measurement is superfluous in this case. Though as these devices are rugged, meant for sending concrete-material measurement information, and inexpensive, then this new use for them is appropriate.

[0055] As hydraulically setting materials increase in temperature as they set, and increased temperature also indicates that setting will increase faster after material leaves nozzle, material temperature is very helpful, particularly in determining a relative dose of an admix that includes a set accelerator. This information is very informative to at least display to User, and can be a determinative factor in corrective action taken. Software in CPU can be set with temperature target values where a given viscosity is given a higher factor in terms of corrective measure action, or viscosity values can always be adjusted by temperature for purposes of corrective action. For example, if a vane measurement results in an equivalent slump of 1 ” (25mm) which would be normally good for printing, but the material temperature is 90 degrees F (32C), then admix proportion should be reduced, because the material will set up more quickly than preferred at that temperature. So, it is more beneficial to integrate temperature information into the digitally-controlled corrective system 12, and this may mean integrating proprietary systems with the system 12. System 12 can vary considerably from the embodiment shown here, according to User override preferences, proprietary manufacture, integration of existing monitoring systems, and arrangement of electronic equipment integrated into the correction system.

[0056] The following embodiments show several other variations of viscosity monitoring system 10, which can each be interchangeable with variations of active correction system 12. Some differences with version 2A are discussed below, without repeating information already provided for 2A.

[0057] An assumption is that there is an initial proportional dose of admix, the properties of that initially modified print material (with that initial proportional dose of admix) are measured, those measurements are compared to preferred properties of print material, and a change in proportional dose of admix is made, if necessary. The mode of how the dose is changed can vary. In this embodiment it is the CPU telling the active system control 29 how big of a change to make to the pump control 38. This change, up or down, can be determined by comparing to material property target values set (within an automated system), or in other embodiments, this can be entirely manual and based on visual interpretation.

Figure 2B

[0058] This is an embodiment showing an extruder drive and feedback unit 40B that is employed to provide viscosity data. This method saves the cost of an independent monitoring system 10A and replaces it with an integral viscosity monitoring system 10B, whereby the torque required for print material extrusion is measured in order to determine the print material viscosity, and so its printability.

[0059] Data is generated from the torque required to extrude a given print material though print material extruder 18, and is initially correlated empirically with printing performance, in order to determine which torque values correlate to degrees of printability, or printing rate, for a given print material. This method of measurement is more specific to factors of print material mix design, such as aggregate size and proportion, and binder content, but then these factors are similarly related to printing behavior. Again, it is relative material properties that are most helpful in determining any adjustment to admix dose for a given print material.

[0060] An optional vane 27 is shown attached to the shaft for extruder 18, and such vanes of proprietary design are sometimes already present in container 6 as a means to remove air pockets from print material, etc. In this case, the vanes 27 further the intermixing process of admix and print material, and provide continued shear forces into admix, if needed to facilitate passage of thickened print material into extruder. Inclusion of vanes has value in further determination of viscosity by measurement of vane resistance. This use of vane resistance is not necessarily determinate of viscosity, in that the torque resistance of the extrusion process is quite frictional, and tends to be the dominant factor in torque generation, however vane 27 size can be increased as necessary, along with provision of resistance-elements to print material spin within container 6 (discussed below), so that the significance of vane 27 as a measurement device can proportionately increase, as part of system 10A. Extrusion resistance alone is viable for relative viscosity measurement, and the combination of extruder/vane rheometer is viable and improved.

[0061] As the power requirement of extrusion is high, a motor 42 for this purpose is suitably a larger, such as a 3-phase, with a controller 44 that is a 3-phase variable frequency device, for example. Extrusion torque can be determined after including power losses associated with the VFD single-phase-to-3-phase conversion, and in fact this motor drive method can be used for the system 10 of Figure 2A, or vice versa.

[0062] A shaft torque measurement device 46, such as employed to measure motor outputs, can be used for more precise determination of torque applied to print material extruder 18, and so more accurate determination of relative viscosity. Device 46 and associated components can be a rotary torque sensor system, designed for testing motor torque at measured rotation speeds, such as those manufactured by the FUTEK corporation, 10 Thomas, Irvine, CA, 92618. This application involves higher torque values than that of the device 32 of Figure 2A, so a torque sensor made for higher loads is appropriate.

[0063] This version of the embodiment indicated in Figure 2B, is where the device 46 is shown sending a signal back to system 12, however this signal can also be sent to the extrusion control system 8, relating to preferable printing speed modifications, etc, based upon print material consistency. Any of the monitoring or feedback systems disclosed can be linked to do this, but as this system tests print material right immediately before it is being printed, this feedback-to-modify-print-speed can avoid creating flaws in a print operation underway, for example because of a print material that may be too fluid to print at a high rate.

[0064] If device 46 is not present, print material information can be sent from the controller 44 (or 30 of Figure 2A) or as otherwise described herein. As only relative torque values are necessary, device 46 is optional. Where extrusion forces are preferably standardized for determination of preferable print materials designs over different jobs, then use of device 46 is warranted.

[0065] What is clear from Figures 2A and 2B is that the analysis systems 10 A and 10B and the correction system 12 (and variations) are independent of each other, in that variations of system 10 can be used interchangeably with a given system 12. Any embodiment of a measurement system disclosed, can substitute for another, while interacting with a given correction system. The correction system 12 can be totally autonomous, or simply informative for the User; and it can automatically make corrections other than admix dose rate, such as adjustments to concrete or print material water proportion.

Figure 2C

[0066] This shows an independent viscosity measurement system that is a vane system concentric with the extrusion system axis, allowing the vane rheometer to be centered in container 6. This allows the entire container geometry to be used for a single-axis independent system, and each vane 27’ to be larger if required for better measurement. Signals 31 C and 41 C to and from monitoring system 10C, and drive 40C, are based on this geometry. This design having the vane rotation separate from the extrusion rotation, as the advantage of being able to continue stirring the print material during pauses in extrusion. More specifics of the mechanical aspects to allow concentric geometry is shown on Figures 3 and 4 following.

Figure 2D

[0067] This shows use of an active inline mixer 23 that rotates mixing pins, and extrudes material within the pumping line, if necessary. Such a mixer is disclosed in literature on cementitious 3D printing, and is generally used for cementitious materials having aggregates less than 6mm. An example of the active inline mixer is that of EP patent number EP3664980B1 , “Method for the 3d-printing of mineral binder compositions”, by Laird et al, filed 08/08/2018, herein referred by reference. Past the mixer is an ultrasonic testing assembly 48, which is fully described in figures 7A and 7B. In this embodiment, the tester assembly 48 is shown between inline mixer 23 and container 6, and includes a signal 31 D sent to an ultrasound tester within assembly 48, and a received signal 41 D, that is analyzed by a data logger, and CPU with software developed by the ultrasound tester manufacturer. Assembly 48 also includes a temperature sensor returning a signal 15. [0068] Signal 41 D from ultrasonic tester assembly 48 will vary according to the stiffness of material, in that sound travels faster as cementitious material viscosity and hydraulic set (and false set) increase. So, an ultrasound relative rate of travel can be used to determine whether the given proportion of admix, or of other factors affecting mixture, should be adjusted to optimize printing. “Relative rate” is used as the relevant term, as further factors are involved, that do not necessarily affect material viscosity or set, such as material density or proportion of aggregates, etc. What is determines is any proportionally small change in sound velocity though the other “samples” of the same material mix design, at the same temperature, and that was previously printing well, to determine if corrective measures are needed - before any irreparable 3D printing problems occur during a large print. Absolute velocity values are generally not very relevant for this new use of the device. In embodiment 2D, as tester 48 is located to test before material is withheld in container 6, further setting of material should be anticipated before extrusion, and this effect should be taken into account in the signal interpretation. To avoid interference of ultrasound measurements due to movement of measured material, they can best be taken at moments when the material supply to container 6 is paused, which is part of normal operation. The length of conduit 25 between mixing and testing should be reasonably minimal, such as preferably less than a meter, so that the amount of modified material left static is minimized during pauses in pumping.

[0069] Alternatively, the active inline mixer 23 can be used to determine relative viscosity by a measure of the torque required for intermixing the print material with a thickening admix, or with a set-accelerating admix, as is disclosed for drive 40B, and elsewhere above. Torque can be measured by the power draw of the active mixer 23, where a power supply line 47 (return line not shown), is connected through a power meter 59, and that signal 51 is sent to an appropriate embodiment of the active correction system 12. Or meter 59 can just be read by User in order to determine relative viscosity. As the rotational speed of mixer 23 is controllable, knowable, or can be kept essentially constant enough by design, the power drawn (and rotational speed, if necessary) can provide sufficient indication of print material relative viscosity. If voltage at the meter 59 will remain constant enough, then it can be an amp meter.

[0070] This extrusion system has no mixing action shown in container 6, as it is optional. In its place, to minimize air entrainment in mixture, vibrational consolidation means to material can be utilized - in container 6 or along the line before or after it. The lack of mixing vanes 27 (such as of Figure 2B) is solely an illustrative example, as in this case of modifying print material before it reaches the container, is a case where mixing vanes are preferable - to apply shear onto the already-modified mix so that it does not get too viscous in the container.

Figure 2E

[0071] This shows an embodiment where tester assembly 48 is located beyond container 6 and extruder 18, and inline mixer 24 is located for intermixing before the material enters container 6. In this case, tester is located post inline mixer and further mixing as occurs within container and extruder, so that mixture is essentially at the stage it will be in for printing. This point of measurement of mixture is a factor in interpretation of data taken from signal 41 F and temperature readings. An optional nozzle 45 is shown, as a means to extend the point of discharge so that the additional width presented by testing assembly 48 is not an obstruction to clearance requirements of the printing process. Nozzle 45 can be whatever length is necessary for this purpose.

[0072] With tester assembly 48 in this location, it may be necessary for very brief pauses in material extrusion for ultrasound measurements to be taken, because of interference from extrusion noise and material motion.

Figure 2F [0073] This shows an embodiment where critical elements of the present invention are all beyond the extrusion process, and a withholding container is not relevant or necessary to this modification and measurement process. This sequence shows use of inline mixer 24 subsequent to extruder 18, where extruder is really a concrete or mortar pump to push material though mixer 24 before it passes through tester assembly 48, and then though nozzle 45, where it is printed. There can be a length of conduit between mixer 24 and tester assembly 48, where this is preferable in developing material modification maturity before ultrasound measurements are taken.

[0074] Alternatively, as the active inline mixer 23 (of Figure 2D) is also an extrusion pump, then it can serve in place of both extruder 18 and line mixer 24, so that the tester assembly 48 is connected below the mixer 23.

[0075] Combinations of these embodiments are entirely viable and helpful to the 3D printing or rapid slip forming process, etc. For example, the vane rheology measurements such as 2A, 2B, and 2C can measure material before modification, in order to determine a most-beneficial dose of admix, for a post-extrusion modification, such as 2E or 2F.

Figure 2G

[0076] This shows an embodiment where material viscosity is measured by an independent system 10G that uses a penetration type of viscosity meter, such as is used with the ASTM C403 method “Standard Test Method for Time of Setting of Concrete Mixtures by Penetration Resistance.” Unlike the Vicat needle test which is a measure of penetration, the apparatus used in ASTM C403, and also AASHTO T197, measures the force required to cause a given amount of penetration in order to determine the amount of set of concrete. This facilitates remote and automated testing, as a predetermined amount of penetration is established. The ASTM C403 utilizes a set of six different-sized penetration pads, with the largest of 1 square inch (645mm^A2) area for initial stages of concrete set, and this size or larger is appropriate for the present invention. The ASTM C403 procedure is to press the pad 1 inch (25mm) into the concrete over a time period of about 10 seconds. The resulting force is interpreted to give an indication of the amount of set of the concrete, and for stiffer mixes such as 3D print material, the viscosity.

[0077] The concrete tested is actually mortar, as the coarse aggregates (over 4.75mm) are removed for penetration testing accuracy, and so for a continuous testing of print material, this method would be more consistently accurate when used for mortar. However, for concrete having coarse aggregates, using many repeated measurements will average out the variations caused by larger aggregates, so the concept is still valid. Importantly, the measurements taken for the present purposes of determining viscosity, are for relative values that do not need to be correlated to ASTM standards, so deviations from that process are not a problem.

[0078] A pressure measuring ram 35 is used to take these measurements.

Preferably these are in conjunction with use of an external vibrator 43 that is attached to container 6. The reason for this is to use momentary vibrational shear to level the stiff material to height shown as 14, because the penetration process is best started with a definite flat starting plane for the penetration measurement. The range finder 16 can be located near ram 35 (not shown that way for clarity), so the distance to top of print material is known or controllable. Ram 35 can be an electrically powered actuator, with loading determined from electrical resistance to generate signal 41 G. Or ram can be hydraulically powered with an integral dynamometer or strain gage sending signal 41 G back to a receiver. Ram is connected to the side of container 6, preferably at least a couple of inches (50mm) from the surface. Signal 31 G can be sent to ram via a controller at regular intervals. The load history of the actuator can be used to determine when it first encountered concrete type material, or it can be coordinated with the rangefinder 16.

Figures 3 and 4

[0079] These show a concentric viscosity monitoring system 60, so named because its rotation axis is separate but concentric with the extrusion axis. In Figure 3 vanes are shown flat to the view direction, to show clearances; and in Figure 4 some are shown at a 45-degree rotation, for clarity.

[0080] An enclosure 54 for motor 20 is attached to the container 6, with a set of pins and latches, as is common with 3D-printer-head geometry. In this case it also houses a geared drive system 52 for a drive 40C and a gear enclosure 80 for a pinion gear 70 and a beveled ring gear 72. This reduction gear is unique in that a shaft 74 must pass though ring gear 72 without attachment, as these two concentric systems are independent. A bearing 82 and a bearing 84 are provided as needed for a particular mechanical geometry, and a bearing is also within the ring gear 72, not shown for clarity. This bearing can be press fit onto shaft 74. Alternatively, drive 40C can be mounted on enclosure 80, which itself can be a sealed enclosure only if a seal is provided at shaft 74, as well as where both gear shafts leave the enclosure.

[0081 ] A drive tube 56 is concentric about a shaft 64, as fitted by at least two of a bearing 62, each that press fit, so that the shaft supports eccentric loads to tube 56. The shaft 64 must have sufficient support at the extruder 18, and at its upper end, described above, for purposes of supporting bearings 63. The bottom is sealed by a shaft seal 66. Tube 56 is of pipe material sufficient for torsion force resulting from rotating a given number of a vane 58 required for viscosity testing, as would be the case for all physical aspects of the embodiments of the present invention.

[0082] As container 6 needs to detach from enclosure 54 for access, shaft 74 has a slip coupler 76 connecting with shaft 64, as is common with such 3D printers now. Coupler 76 must be supported sufficiently (from above) for loads to tube 56, as provided by bearing 84 and within ring gear, as required. Tube 56 also has similar a slip coupler 104 that allows disconnection with the gear drive system 52.

[0083] As drive 40C is providing torque feedback to system 12, allowance must be made for gear reduction, both in proportional vane rotational speed and in gear system friction. Drive 40C can be of the components indicated in Figures 2A or 2B.

[0084] As the torque testing is traditionally a measure of material shear, resistance to the induced rotation can be provided by a number of a shear rib 78, creating a shear field, as required to prevent a spin of the print material mass, as is common on vane rheometers. Shaft 64 can include a number of a mixing vane 68, also for purposes of providing shear resistance for vanes 58, in that system 60 can be made to rotate in opposite direction of shaft 64. For vanes that are solid without openings, the space between upper and lower vane sets should be at least 4 times the largest aggregate in the print material - for purposes of measuring print material shear. Vanes 68 are also useful for furthering the intermixing of admix/print material if necessary, and can be employed for this purpose before print material leaves container 6. Vanes 68 will disrupt the premature setting or false setting of print material at the bottom of container, facilitating flow to the extruder after any printing delays are encountered.

Figures 5 and 6

[0085] This device includes multiple units of the independent viscosity monitoring system 10. Alternatively, this device can be a single system, or a single non-concentric system 10. In Figure 5, vanes are shown flat to the view direction, to show clearances; and in Figure 6 they are shown at random rotations, for clarity.

[0086] In this case, three units are labeled as 10A, 10B, and 10C. Each of these units can be the same or each can serve a specific purpose that is unique from the others, and/or each can be tasked to test at different rotational speeds simultaneously, for example, so that acting as a group, they can determine an extrapolation of yield stress in a single test, rather than requiring a series of sequential stepped tests at different rotation speeds. This multiple-input test can be run continuously without change, providing a continuous data stream, and as extrapolated by the CPU, that will immediately indicate any change in plastic viscosity and print material yield stress. Alternatively, the multiple-simultaneous test can be run intermittently, only as needed. Combined with an automated correction to the admix pump controller 38 (of Figure 2A), the active viscosity control system 12 can make corrections to print material viscosity that are continuous and immediate in effect.

[0087] Alternatively, each unit 10 can be tasked with varying degrees of continuing the admix/print material intermixing process, or solely providing the entire intermixing process in lieu of any other inline mixer, where the viscosity testing is accomplished primarily with one system arranged to receive print material last, such as 10C. In this case, an entry fairing 100 is located to direct print material flow, and combined with the rotation of an optional vane 69 or vanes attached to shaft 64 with a pair of a shaft clamp 98, print material migrates first toward unit 10A, then 10B, and then 10C. As print material is directed to mixing vane sets in a sequence that is determined by a modification of geometry in container 6, each of vane sets A,B,C. The corresponding monitoring systems A,B,C can be optimized for maximum benefit for that stage of print material thickening development encountered. Vane set A can be designed primarily for continued intermixing, vane set B can also be designed for further intermixing, and vane set C can be optimized for print material analysis. This sequence will present print material that is further-affected by admix at each vane set, so vanes and monitoring systems will account for this. For example, vane set A can present a larger surface area with variable clearance to other surfaces, than B or C, and/or C can have a geometry that allows torque-based shear analysis that works with a very stiff print material (as it is last in line), such as utilizing more elements that each present a smaller area, with sufficient clearances to other surfaces to ensure valid testing, even though mixing utility will suffer. While vane set A and its surrounding surfaces can have a geometry primarily optimized for mixing, even though testing validity may suffer.

[0088] To save cost, vane sets A and B can be utilized solely for intermixing, with only set C attached to a monitoring system (though even if sets A and B are not idealized for measuring print material properties, they can still provide useful information). In the case where inline mixer 24 (Figure 3) is not providing sufficiently intermixed print material/admix, such as where positional or length restrictions may compromise intermixing, or inline mixer must otherwise be minimized, then the tasking continued intermixing with a multiple vane set system may be preferred. If the inline mixer must be omitted for any reason, then it is possible to simply inject admix into the container 6 at a location facilitating intermixing with multiple vane sets. When vanes are utilized primarily for mixing, providing clearances to other surfaces or objects is not as critical. Conventional mortar mixer paddles will commonly be adjusted to wipe right against container surfaces.

[0089] Easy removal of container 6 from enclosure 54 is possible, as all of the shafts have a slip coupler 96. As this design adds more motors inside the enclosure, sufficient additional heat dissipation is required for this additional heat generated (so that all motors can remain within operating parameters), not shown here.

[0090] To avoid stagnant areas in the print material/admix mixing process, one or more of a fairing 102 can be installed. Any number of the shear ridge 78 can be installed as needed to provide shear resistance for the rotor vane rheology process, or for rotary mixing. The mixing vane set 69, will provide shear resistance to vanes 10, regardless of spin direction. It will further the intermixing process and facilitate introduction of very stiff print material into extruder 18 - particularly in being the only concentric vane set in this multiple vane set system.

[0091] Alternatively, units A,B,C can all be on a planetary gear system for an improved mixing process, such as with a large interior ring gear system aligned with the container wall. This arrangement was discarded because of high costs for shafts’ stability from side-loading and issues with data acquisition wire paths.

[0092] Figures 7A and 7B

[0093] These show two section views of ultrasonic testing assembly 48, which is a system to allow a novel use for an existing technology - presently used to determine the state of hydration and curing of cementitious materials, by measurement of ultrasound transmission speed through the material, which varies as the material hardens. Given that there is also variation in ultrasound transmission rate corresponding to changes in material viscosity, false set, and stages of initial set of cementitious material, then the measurements can be used to determine these changes in such material that is utilized for 3D printing. The change is ultrasound velocity relative to viscosity, preliminary set, and false set is relatively small compared to those changes as the material hardens, but it is enough change to be measured and interpreted by the device. The related software is specifically designed to determine change in material property by determining change in ultrasound velocity, as in determining the first derivative of repeated velocity measurements. The specific velocity is not important; a given initial velocity can be determined by test, and correlated to a given mix design at a given viscosity and temperature, etc, at the start of a print. Then, what is relevant is to determine any change in that velocity, which correlates to a change in at least one material property affecting printing behavior. This change can then be linked to a corrective measure, such as a corrective change in admix proportional dose.

Ultrasound is a variable that can be easily monitored, is indicative of relative printability, and then can be used to determine a corrective action for improved printing.

[0094] An example of the ultrasonic tester 106, and related digital equipment, is that manufactured by UltraTest GmbH, Am Schmiedeberg 6, 28832 Achim, Germany.

Tester 106 can be a silicone measuring mold, such as model number 150-70 bl32 HR, having vibration absorbers 128 per the manufacturer. In this embodiment the bottom of the silicone mold is cut out so that material can flow though the mold, rather than remain static within it, as originally intended. An entry conduit 130 and an exit conduit 132, having the same diameter as a testing void 120, allow new material to move into place for testing. A transmitting probe 116 and a receiving probe 118 (Ultrasonic probes model number E90-12) are elements supplied by UltraTest to conduct the ultrasound rate measurements though material in void 129, with signal 31 sent, and signal 41 received, by a BP-700 Pro Ultrasonic-Tester or an IP-8 Ultrasonic-Multiplexer-Tester V6 (multiple channel), and pre-calibrated connection cables, all by UltraTest. A temperature sensor 122, also sends a signal 15. UltraTest software on a CPU connects by USB to the data acquisition units, for interpretation of the ultrasound and temperature data. This information is then used to determine the result of a change in admix pumping rate, or the other changes affecting material printing behavior, discussed. [0095] The purpose of the assembly 48 is to provide protection for tester 106 that is as quiet and as vibration free as practical, given the construction environment. A casing 110 is steel or the like, and can be made of two parts that meet at a break seam 114, and are clamped together by a number of an over-center latch 112. Probes 116 and 118 are sealed at casing with a rubber grommet 124 and sensor 122 is sealed at casing with a rubber grommet 126. Conduits 130 and 132 are sealed at each of a flange 136 by a groove 134, which can be that matching a cam-lock connection which is very common in 3D printing mortar materials. A gasket (such as is used in concrete hose connections), or as is used in cam-lock connections, or O-rings, can be employed to make these connections seal. Likewise, a common pipe size is 50mm, which can match a silicone void 120 of tester 106 as manufactured by UltraTest. [0096] A viscoelastic barrier 108 is made to fit tester snugly into case 110. This can be milled to fit, and it should be a tight fit between casing 110 and tester 106, so that the latches 112 close tightly. It is preferably of a highly viscoelastic rubber material such, as a chlorinated butyl rubber, having Shore A hardness between about 30 and 60. Any portion of it should be at least about 3/4” (18mm) thick for vibrational protection of tester 106. Alternatively, barrier can be cast to fit, such as using an RTV silicone material that is also viscoelastic. As barrier 108 dimensions have some determination on the pressure capacity of assembly 48, and accurate fabrication is warranted, though as tester 106 itself is capable of cementitious environments and pressure, so material or liquid seeping through at joints between barrier 108 and tester 106 is not problematic, as case 110 is the pressure vessel for the assembly. The fit and stiffness of Grommets 124 and 126 are more likely to be limiting factors in pressure capacity, and they need to be selected for that purpose, and a careful fit of barrier 108 helps this. Washers are shown outside of grommets 124 that can tighten, with alien set-screws, onto the shaft/body of probes 116 and 118, for pressure support of these grommets. The same type of approach can be taken with grommet 126.

[0097] To facilitate a sealed fit of barrier 108, and to improve vibrational protection for tester 106, use of a viscoelastic caulking will be helpful, in fitting an intentionally- undersized barrier into casing, and will help with pressure-proofing the casing apertures for probes and wires. A soundproofing viscoelastic caulking can be used, such as “Green Glue,” by the Saint-Gobain company, 12 place de I'lris 92096 La Defense Cedex, France. Alternatively, a caulking such as this can be used to cast an entire barrier in situ. Mold release material can be first applied to the parts that will need later removal.

[0098] The thickness of casing 110 depends upon the anticipated use. In most cases assembly 48 will be near the end of a pressure line, so that its pressure environment is considerably less than most concrete pumping conditions. For most 3D printing applications, casing can even be as thin as 3mm, and for higher pressure conditions further from the point of discharge, casing may need to be about 6mm; and for larger diameters of line where normal concrete is used at high pressure, then even as thick as 9mm can be appropriate. [0099] While the movement of material though tester, while being measured with ultrasound, is a minimal amount of translational movement, relative the speed of sound; the noise from pumping and moving the material will interfere with the sensitive transmission and reception of the ultrasonic device. So, at least in some cases, it may be necessary to stop the material movement for this reason. As each ultrasound measurement takes only milliseconds (for this new viscosity-measurement application of the device), this stoppage can be minimally disruptive to the printing process; and for an embodiment such as Figure 2D, or any case where the measurement is taken before or within the reservoir of material (such as that withheld in container 6), the momentary stoppage of the material supply system (such as 4 of Figure 1 ) for taking ultrasound measurement has no effect on the printing operation. Likewise, tester 106 can be located within container 6 so that fresh material is moved through it, and whenever material supply to the reservoir is stopped (the level 14 has reached a high level as determined by rangefinder 16, of Figure 2A), ultrasonic testing can be undertaken at these moments.

Figure 8

[00100] An example of a mini volumetric mixer 106, is the Mud Mixer™, US Patent No. 10,259,140, manufactured by Mud Mixer, 5109 82nd Street, Suite 7-1215, Lubbock TX 79424, United States. This unit accepts combined dry mix materials in a hopper, and mixes them volumetrically with water in an auger mixing system 108, shown with a cover removed, powered by an electric motor 114. The relative amount of water can be adjusted by a control 110. The controlled flow of water is run though a line 132. There can be multiple lines for water or water discharge into the mix. A proportional dosing system 158 can modify that water to include cement thickeners or accelerators and the like. To engage this system, the water line 132 is routed through a line loop 134, by closing valve 138, and opening both valves 140, so that water flows though a proportional doser 136. The doser can be those used for controlling proportional chemical dose into a water flow, such as the Dosatron model D07RE5, by Dosatron International, LLC, 2090 Sunnydale Blvd, Clearwater, FL 33765. Admix flows from a container 142 though line 144 into doser 136. The water is then modified with a controlled proportion of admix as it discharges from line 146 into the auger mixing process. This doser 136 would be suitable for addition of a liquid admix that will not react too strongly when in contact with plain water for a short distance, and would not clog any nozzle that may be required at the end of line 146. This could be a liquid cement-accelerator, or a pH-sensitive thickener, or a rheology modifier that reacts with cement - but minimally or less so with plain water. Doser 136 can be adjusted manually to modify the mix to build up vertically, or for another modification trait, as preferred. As the loop 134 running through doser 136 creates more resistance than original line 132, the proportional rate of water flow selected may have to adjust upwards when this system is in use, to maintain the same proportion of water in the mix.

[00101] A direct admix dosing system 118 can be accomplished by any of the systems previously disclosed, such as the admix pump 36 and controller 38 of Figure 2A. The dose rate can be automatically controlled by linking it to the power draw of the motor 114, with a power-admix link system 116, which can be according to one of the previous disclosures, such as that of Figures 2A though 2E, and 3 through 6. In this case, where the rotational speed of the relatively low-powered motor is fixed, except as slowed by load, and it is this load that is used by system 116 to determine a change in admix dose rate, this can also serve as a modulating system. When the auger loads up, it slows down, and the motor draws more power. According to previous disclosures, this will reduce admix proportion, which is appropriate - even to keep thickening proportion the same as now the auger has now slowed down, though the preference is to also have a reduction in admix proportional to increased motor loading. To offset this slowing down effect, the change in proportion of admix can be increased, relative to the change in the motor power draw. More specifics on this are disclosed with Figure 10.

[00102] The admix discharges from line 120 in the auger mixing system preferably at a location where it avoids initial contact with dry cement. It can be aimed right at an introduced flow of water, or down the auger system far enough where it will hit wettened material, and far enough from the terminal end to intermix sufficiently. A liquid admix will intermix sufficiently with less mixing action than it takes to mix concrete entirely. Alternatively, the dosing system 118 can deliver a dry admix with a small auger delivery system, linked by system 116. In this case, the intermixing action would benefit from the entire length of the auger system 108, so the discharge point should be near the upper end.

[00103] Mixer 106 can be used to build concrete freeform vertically directly if it can be positioned to discharge directly above a vertical shape being built. This can be accomplished by lifting the mixer with an excavator arm with a bucket, such as by using a lifting cradle 156 that is clamped to the excavator bucket with a thumb attachment 154. There are many other well-known ways to attach the mixer to an excavator or robotic arm. This arrangement can vastly improve the efficiency of building landscape walls and vertical decorative concrete, etc.

Figure 9

[00104] A volumetric cement-mixing truck 122 combines sand, gravel, cement, water, and sometimes admix, volumetrically, into an auger mixing system 124. The load on the auger 126 is a measure of relative viscosity of the concrete being mixed, and this load is measured or measurable on the hydraulic system running the auger. A gauge connected to the auger system, where hydraulic pressure would be measured at the circuit powering the auger mixer, upstream of that motor, to measure and send relative hydraulic system pressure, 112, can be one such as GS4200-USB Digital Pressure Transducer, a USB powered digital pressure transducer, by ESI Technology Ltd, Wrexham Technology Park, Wrexham LL13 7YP United Kingdom. This can be connected to a digital system such as that disclosed in Figure 2A, where it can be linked to admix dose control in the same way as drive 40A. It can provide a relative change to the rate of the volumetrically-controlled admixture dispensing system already on a volumetric mixing system. So this allows the auger system 124 to measure, and provide a basis for a correction to, the volumetric dose of a thickening admix. [00105] An admixture dispenser 148 is shown in the usual location, where is adjacent to the water dispenser, both normally concealed from view. A dispenser 148’ can be at an alternate location, where the materials are sufficiently wetted to improve admixture effectiveness, or where this admix system is independent of the conventional admix system already on board the volumetric mixer.

[00106] Concrete modification can be made with a proportional dosing system looped into the existing water supply line, such as that disclosed per Figure 8. This would be the water volumetric component primarily controlled at the panel 128, and metered by an onboard pump. The higher rate volumetric process in this case would require a larger doser, such as a Dosatron model D40MZ5BPVFHY. Any flow reduction by the introduction of increased line resistance would need to be addressed.

Figure 10

[00107] This shows a simplified example for a logic flow chart for automatically modifying print material viscosity incrementally toward a target viscosity. User selected values can include those of these terms:

VT: Target Viscosity

AVD: Degree of viscosity change, positive and negative, where their combined absolute value defines a range of acceptable viscosity. The positive and negative terms do not need to have the same absolute value, in that a higher viscosity may limit workability abruptly; so in this case the positive VD could have a lower absolute value than the negative AVD.

AAo: The initial amount of change to the dose of admix (the initial value of the AN series).

AT: The time period between sampling and corrective action, or a set of measurements and corrective action based on that set.

P: The proportion (proportional reduction) to the amount of change, to be used as the subsequent amount of change, where the absolute value of the amount of change was determined to be too great. A value between 0 and 1 , to stabilize the iterative process.

[00108] Figure 10 shows a graph of relevant viscosity values, where VT, the ideal viscosity, is bracketed by VL, the lower limit of acceptable value, and VH, the higher limit of acceptable value; creating AVD positive and VD negative. An example of a measured viscosity, VN is shown a distance AVN below VL (a measured viscosity value lower than the lower limit of acceptable value), giving this AVN a negative value. A corrective action is taken to increase (in this case) the amount of admix by AAo. After a predetermined time period, AT, the viscosity is measured again. This is repeated until the viscosity is within the acceptable range.

[00109] In the case where the selected AAo was too great of a value, there will be overcorrection, which can lead to instability rather than leading toward a target viscosity. User experience, or recognition of instability, would lead to a proper selection of AAo, but where the selected value was too great, a stabilizing routine can iteratively reduce AA by measuring convergence to or divergence from the target viscosity.

[00110] In other words, the automatic measurement/correction feedback loop will sometimes require modulation to avoid potential instability. The dose correction amount can be limited to a maximum step, and with a delay that is greater than the time it takes to process measurement of the newly-modified print material, before another correction can be made. The maximum corrective step can be limited; it can be a selected smaller-proportion (P) of the of the initial admix dose, such as 0.1% or 20%, etc. This corrective-step proportion is related to the sampling rate, which can range from milliseconds to many minutes, depending on the embodiment. If the measurement system has sampling rate of a shorter time period than the time it takes for a modification to be measurable, then the preferred solution is to require a given number of measurements be taken and averaged before any corrective action is taken. In any case, the target viscosity should be a selected range of values, and corrective action result only from being outside this range. All of these values can be selected and changed by User input, and then controlled by code processed by the CPU. In any case, the distance between print material modification and measurement of that same material must be factored into corrective action timing; the time delay resulting from this distance can be a User selected value.

[00111 ] The logical steps are as follows:

Material viscosity VN, where N indicates an iteration sequence, is measured at step160, by any of the means previously disclosed where electronic data of the measurement can be acquired. At step 162, VN is compared against previously established values, Viand VH, the lowest and highest acceptable values within a range of acceptable viscosity. If the measured viscosity falls outside of this range, the next step is 164, where a determination of the process closing to, or diverging beyond, the target viscosity, made by comparing iterations of differences, AVN, which are directional. If the previous measurement difference was a negative value, and the present one is a positive value, this means the change in admix, AN (of step 166) was too great, and the target was overshot. In this case of an unstable process, step 164 sends the process to step 166, where the amount of admix correction is reduced by P, defined above and selected by User. P proportionally reduces the amount of change in admix dose so that the amount of correction will reduce the amount of change in the subsequent iteration, leading to an acceptable viscosity. Both step 164 and 166 go to step 168, where a determination is made for AVN being positive or negative, so that the correction can be to increase admix 170, or decrease admix 172. These steps lead to step 174 which is to pause the subsequent measurement, or set of measurements, until the material receiving modification in admix dose can reach the point of measurement. The time period T is selected by User based upon the delay of a particular embodiment, and experience with the system correcting without too many iterations or becoming. This is the automatic viscosity correction process.

[00112] In the case where step 162 determines that the viscosity is within range, no change is needed. In this case, the pause at step 174 is not actually necessary, though it is a useful means of creating a sampling rate. There can be another smaller AT where the viscosity is acceptable, which can simply be the measuring device sampling rate. This is the automatic viscosity monitoring process.

[00113] Here is an example for an automated method for building a vertical shape of a material which will harden in place, the material consisting of aggregate, binder and water, the material having a measurable viscosity, and a range of values for a preferred viscosity for a vertical build of the material, which is determinable, and a means for a correction to a viscosity that is outside of the range of the preferred viscosity, the steps of the method being the aggregate, the binder, and water are intermixed, comprising the material, the material having a given viscosity, a modifying admix is intermixed with the material, at a proportional dose, modifying the material by imparting a modified viscosity to the material, the degree of the modified viscosity being approximately relative to the degree of proportional dose, the modified viscosity is measured, and compared with the range of values for the preferred viscosity, if the modified viscosity is outside the range of the preferred viscosity, then the correction is made to the proportional dose of the modifying admix, and this step is repeated until the modified viscosity is within the range of the preferred viscosity.

Figure 11

[00114] This logic is the same as that for Figure 10, except that this is for a correction to the proportion of water, this correction being AWN, rather than AN for admix. In this case, the direction for correction is the opposite, in that less water “thickens”, so the action taken in change of the amount of water is the opposite. As reducing water to allow vertical build is very limited in usefulness, as it also proportionally reduces workability, this is more useful as a means to maintain the same workability under varying conditions. Where new aggregate entering a mixing system is dryer, or the local environment has suddenly changed - such as shade to sun, this system can provide monitoring and correction of the water proportion, to allow consistent printing under those changed conditions. This water-adjustment system can apply to, replace, or augment, any of the previously disclosed admix control systems.

[00115] The steps in the process of adjusting the relative amount of water in the print material or concrete are the same as for adjusting the admix, described above, with two differences in logical steps. Adjustment is made to the amount of change to water per iteration, step 180 in Figure 11 . Where adjustment is made, it is in the opposite direction as with thickening admix, so that to increase material viscosity, water amount is reduced, step 182; and to reduce material viscosity, water amount is increased, step 184.

[00116] The time period between a given correction of material viscosity and subsequent material measurement is much longer for this case where the amount of water is being adjusted, in that the distance that typically each iteration of changed material must travel a longer distance to reach the point of measurement. Also, as a too-low water content will make the mix unpumpable, and too much water will make the material unstackable; so, any water proportional change must be small comparted to the total water proportion, such as no more than a few percent maximum. The water content sensitivity combined with the change of a line blockage or print collapse, makes the automation of water proportion change a very sensitive with greater potential for instability. Use of corrections to a thickening admixture is a more robust and forgiving means to control viscosity, while maintaining pumpability and stackability.

[00117] For a volumetric material production process access to control of the relative flow of water is known, and this can be linked to the viscosity control system by various known methods using software and/or hardware, including linking into the electronic controls of the volumetric system.

[00118] In the foregoing specification, the invention has been described with reference to specific embodiments; however, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification is to be regarded in an illustrative, rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention.

[00119] Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments; however, the benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims.

[00120] As used herein, the terms “comprises,” “comprising,” "includes," "including," "has," "having," “at least one of,” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited only to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

Claims

CLAIMS What is claimed is:

1 . A system comprising: a controller for input of at least one of two or more components comprising a mixture for forming a layer, at least one of the components being a liquid, where the mixture has a preferred range of viscosity; and a viscosity control system comprising: a viscosity monitoring system to acquire a series of measurement of the viscosity of the mixture; and an active correction system connected with the viscosity monitoring system; and a means to change a proportion of a component of the mixture that will change the viscosity of the mixture; and where the system compares one or more of the series of measurement of the viscosity with the preferred range of viscosity; and where one or more of the series of measurement of the viscosity is outside the range of the preferred viscosity, the active correction system is activated to change the proportion of a component of the mixture that will change the viscosity of the mixture to receive viscosity measurements and operate the rate controller to control the viscosity of the mixture in response to the viscosity measurements.

2. The system of claim 1 , wherein the rate controller comprises a fluid flow controller.

3. The system of claim 1 , wherein the rate controller comprises a fluid metering valve.

4. The system of claim 1 , wherein the rate controller comprises a fluid pump.

5. The system of claim 1 , wherein the viscosity monitoring system comprises one or more devices to collect vane-measured viscosity or ultrasound-measured viscosity of the mixture.

6. The system of claim 1 , further comprising a reservoir for temporarily withholding the two or more components, the reservoir comprising one or more mixing vanes.

7. The system of claim 1 , further comprising a reservoir for temporarily withholding the two or more components, the reservoir comprising one or more rotatable mixing vanes.

8. The system of claim 1 , wherein the viscosity monitoring system comprises one or more modules to collect material temperature for at least one of the two or more components.

9. The system of claim 1 , wherein the viscosity monitoring system comprises one or more ultrasound transmitting and receiving devices to collect material viscosity for at least one of the two or more components.

10. The system of claim 1 , wherein the viscosity monitoring system comprises one or more devices to collect extrusion force of the mixture.

1 1 . The system of claim 1 , wherein the viscosity monitoring system comprises a penetrometer.

12. The system of claim 1 , further comprising an inline static mixer, an inline active mixer, a mixing container, an open auger mixer, or combinations thereof.

13. A method of placing a layer comprising: providing a feed of two or more components as two or more streams, at least one of the components being a liquid; measuring the viscosity of the mixture; comparing the viscosity of the mixture to a predetermined viscosity or predetermined viscosity range; and changing the amount of at least one of the two or more components so that the measured viscosity is equal to the predetermined viscosity or is within the predetermined viscosity range.

14. The method of claim 13, wherein one of the two or more components comprises an admixture that changes the viscosity of a fluid cementitious mix and the other of the two or more components comprise a cementitious mix or components for a cementitious mix.

15. The method of claim 13, wherein one of the two or more components comprises an admixture that changes the viscosity of a fluid mix of aggregate, binder, and water and the other of the two or more components comprise an amount of aggregate, an amount of binder, and an amount of water.

16. The method of claim 13, wherein the measuring of the viscosity is accomplished by vane measured viscosity.

17. The method of claim 13, wherein the measuring of the viscosity is accomplished by ultrasound measured viscosity.

18. The method of claim 13, wherein the measuring of the viscosity is accomplished using extrusion force.

19. The method of claim 13, wherein the measuring of the viscosity is accomplished using pressure of a penetration device.

20. The method of claim 13, wherein the one of the at least two components is water and further comprising making adjustments to a proportion of water component for the layer as the layer is placed.

21 . A system comprising: a rate controller for input of at least one of two or more components of a mixture for forming a layer, at least one of the components being a liquid; and a viscosity control system comprising: a viscosity monitoring system to measure the viscosity of the mixture; and an active correction system connected with the rate controller and with the viscosity monitoring system to receive viscosity measurements and operate the rate controller to control the viscosity of the mixture in response to the viscosity measurements.

22. The system of claim 21 , wherein the rate controller comprises a fluid flow controller.

23. The system of claim 21 , wherein the rate controller comprises a fluid metering valve.

24. The system of claim 21 , wherein the rate controller comprises a fluid pump.

25. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to collect vane-measured viscosity or ultrasound-measured viscosity of the mixture.

26. The system of claim 21 , further comprising a reservoir for temporarily withholding the two or more components, the reservoir comprising one or more mixing vanes.

27. The system of claim 21 , further comprising a reservoir for temporarily withholding the two or more components, the reservoir comprising one or more rotatable mixing vanes.

28. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to collect material temperature for at least one of the two or more components.

29. The system of claim 21 , wherein the viscosity monitoring system comprises one or more ultrasound transmitting and receiving devices to collect material viscosity.

30. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to collect extrusion force of the mixture.

31 . The system of claim 21 , wherein the viscosity monitoring system comprises a penetrometer.

32. The system of claim 21 , further comprising an inline static mixer, an inline active mixer, a mixing container, an open auger mixer, or combinations thereof.

33. The system of claim 21 , wherein the viscosity monitoring system further comprises a vane to measure vane torque.

34. The system of claim 21 , wherein the viscosity monitoring system further comprises a vane having through surface holes to measure vane torque.

35. The system of claim 21 , wherein the viscosity monitoring system further comprises vanes disposed to measure multiple sequential vane torque.

36. The system of claim 21 , wherein the viscosity monitoring system further comprises one or more vanes disposed to measure vane torque for multiple speeds.

37. The system of claim 21 , wherein the viscosity monitoring system further comprises a vane to measure vane torque using a standardized rheology measurement sequence.

38. The system of claim 21 , wherein the viscosity monitoring system further comprises a device perform a standardized penetration resistance test.

39. The system of claim 21 , wherein the viscosity monitoring system further comprises a device perform a standardized penetration resistance test that can be automated.

40. The system of claim 21 , wherein the viscosity monitoring system further comprises a penetration resistance measuring device that includes a rangefinder to locate material surface automatically.

41 . The system of claim 21 , wherein the viscosity monitoring system further comprises vibrating the material in a container to create an initial flat surface for a penetration resistance measuring device.

42. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to collect extrusion resistance of the mixture.

43. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to collect extrusion resistance and vane torque resistance of the mixture.

44. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to collect temperature measurements.

45. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to collect ultrasound transmission rate.

46. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to collect inline mixer resistance.

47. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to collect mixing auger resistance.

48. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to collect material pumping resistance.

49. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to accomplish shaft torque measurement.

50. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to accomplish stepper motor measurement.

51 . The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to accomplish motor power draw measurement of a mixing process.

52. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to accomplish motor power draw measurement of an inline active mixer.

53. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to accomplish motor power draw measurement of an open auger mixer.

54. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to accomplish motor power draw measurement of a volumetric mixer.

55. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to accomplish motor power draw measurement of a pumping process.

56. The system of claim 21 , wherein the viscosity monitoring system comprises one or more devices to accomplish hydraulic system pressure measurement.

57. A method of placing a layer comprising: providing two or more components to form a mixture, at least one of the components being a liquid; measuring the viscosity of the mixture; comparing the viscosity of the mixture to a predetermined viscosity or predetermined viscosity range; adjusting the amount of at least one of the two or more components so that the measured viscosity is equal to the predetermined viscosity or is within the predetermined viscosity range; and placing the mixture to form the layer.

58. The method of claim 57, wherein one of the two or more components comprises an admixture that changes the viscosity of a fluid cementitious mix and the other of the two or more components comprise a cementitious mix or components for a cementitious mix.

59. The method of claim 57, wherein one of the two or more components comprises an admixture that changes the viscosity of a fluid mix of aggregate, binder, and water and the other of the two or more components comprise an amount of aggregate, an amount of binder, and an amount of water.

60. The method of claim 57, wherein the measuring of the viscosity is accomplished by vane measured viscosity.

61 . The method of claim 57, wherein the measuring of the viscosity is accomplished by ultrasound measured viscosity.

62. The method of claim 57, wherein the measuring of the viscosity is accomplished using extrusion force.

63. The method of claim 57, wherein the measuring of the viscosity is accomplished using pressure of a penetration device.

64. The method of claim 57, wherein the one of the at least two components is water and further comprising making adjustments to a proportion of water component for the layer as the layer is placed.

65. The method of claim 57, further comprising using the layer for 3D print extrusion.

66. The method of claim 57, further comprising using the layer as an extrusion line material that is being 3D printed.

67. The method of claim 57, further comprising vertically slip forming the layer.

68. The method of claim 57, further comprising freeform stacking the layer.

69. The method of claim 57, further comprising pneumatically placing the layer.

70. The method of claim 57, wherein the setting the amount of at least one of the two or more components comprises changing a proportional dose of a thickening admix.

71 . The method of claim 57, wherein the setting the amount of at least one of the two or more components comprises changing a proportional dose of an accelerating admix.

72. The method of claim 57, wherein the setting the amount of at least one of the two or more components comprises changing a proportional dose of water.

73. The method of claim 57, wherein the setting the amount of at least one of the two or more components comprises changing a proportional dose of a rheology modifying admix.

74. The method of claim 57, wherein the setting the amount of at least one of the two or more components comprises changing a proportion of water.

75. The method of claim 57, wherein the measuring the viscosity of the mixture is done automatically.

76. The method of claim 57, wherein the measuring the viscosity of the mixture is done automatically and in substantially real time.

77. The method of claim 57, wherein the the viscosity of the mixture is changed with use of a cement set-accelerator,

78. The method of claim 57, wherein the measuring the viscosity of the mixture is combined with the intermixing process of the mixture and a viscosity modifying admix.

79. The method of claim 57, wherein the measuring the viscosity of the mixture is combined with a volumetric mixing process.

80. The method of claim 57, wherein the modification of the viscosity of the mixture is accomplished by a proportional doser that premixes a controlled proportion of modifying admix with a supply of a water, as a component of the mixture.

81 . The method of claim 57, wherein the measuring the viscosity of the mixture is performed according a to standardized test procedure.

82. The method of claim 57, wherein the setting the amount of at least one of the two or more components is done automatically.

83. The method of claim 57, wherein the setting the amount of at least one of the two or more components is done automatically in substantially real time.