CN111175184A - A device and method for testing the extrudability and mechanical properties of freshly mixed 3D printed concrete - Google Patents
A device and method for testing the extrudability and mechanical properties of freshly mixed 3D printed concrete Download PDFInfo
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- 239000004567 concrete Substances 0.000 title claims abstract description 125
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- 238000010146 3D printing Methods 0.000 claims abstract description 48
- 239000000463 material Substances 0.000 claims abstract description 48
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- 239000002245 particle Substances 0.000 claims abstract description 11
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- B33Y70/00—Materials specially adapted for additive manufacturing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
本发明涉及一种3D打印混凝土可挤出性与新拌状态力学性能测试装置与测试方法，测试装置包括压力机、挤出装置、可移动小车、控制系统和相机，所述压力机为门式结构，压力机顶部中心具有下压杆，所述挤出装置包括推杆、装料筒、挤出筒和支撑架，所述装料筒和挤出筒均为圆筒式结构，装料筒下缘和挤出筒上缘均设有向外凸出的固定环，所述支撑架包括圆环形的支撑台和三根斜向固定于地面的支撑杆，所述支撑台的圆环中心用于放入挤出筒。本发明适用于骨料粒径在0‑31.5mm的3D打印混凝土材料挤出模拟与工作性测试，既能够评价混凝土材料的可挤出性，又能得到3D打印混凝土的流变参数和早期力学性能，为3D打印混凝土配合比设计提供定量指标。
The invention relates to a test device and test method for the extrudability and mechanical properties of 3D printing concrete in a fresh state. The test device includes a press, an extrusion device, a movable trolley, a control system and a camera. Structure, the top center of the press has a lower pressing rod, the extrusion device includes a push rod, a charging barrel, an extrusion barrel and a support frame, the charging barrel and the extrusion barrel are both cylindrical structures, and the charging barrel Both the lower edge and the upper edge of the extrusion cylinder are provided with a fixing ring protruding outward, the support frame includes a circular support table and three support rods fixed obliquely on the ground, and the center of the ring of the support table is into the extrusion barrel. The invention is suitable for extrusion simulation and workability test of 3D printing concrete materials with aggregate particle size of 0-31.5mm, which can not only evaluate the extrudability of concrete materials, but also obtain the rheological parameters and early mechanical properties of 3D printing concrete. performance, providing quantitative indicators for 3D printing concrete mix design.
Description
Technical Field
The invention relates to the technical field of building materials and building construction, in particular to a device and a method for testing the extrudability and the mechanical property in a fresh mixing state of 3D printed concrete.
Background
The 3D printing technology is additive manufacturing technology, the manufacturing of the solid structure is completed in a mode of overlapping the materials layer by layer, a die is not needed, the manufacturing period can be greatly shortened, and the cost is reduced. 3D printing is typically achieved using digital technology material printers. The method is often used for manufacturing models in the fields of mold manufacturing, industrial design and the like, and is gradually used for directly manufacturing some products, and parts printed by the technology are already available. The technology has applications in jewelry, footwear, industrial design, construction, engineering and construction (AEC), automotive, aerospace, dental and medical industries, education, geographic information systems, firearms, and other fields. At present, the 3D printing technology is applied to the building industry, the 3D printing concrete technology is developed, the labor cost can be greatly saved, the period is shortened, local materials are obtained, the transportation cost is reduced, and the requirements of building industrialization are met.
Because the 3D printing concrete does not need a template and is built by stacking layers, the 3D printing technology has higher requirements on the performance of the concrete, particularly the performance of the concrete in a fresh-mixed state. The 3D printing requires that the fresh concrete has sufficient fluidity and cohesiveness, ensures that the fresh concrete can be smoothly extruded from an extrusion head, and has certain shape retention capability after being extruded. In addition, the concrete of the bottom layer after printing should have a certain bearing capacity, be able to bear the pressure of the upper material, and ensure that no major deformation occurs. Therefore, the accurate and convenient test of the workability of the 3D printed concrete and the mechanical property in a fresh mixing state becomes the key for evaluating the printability of the concrete.
However, conventional concrete workability test methods (e.g., slump, etc.) have not been suitable for application to 3D printed concrete. At present, some testing methods for testing the working performance of 3D printing concrete are mostly limited to 3D printing concrete without coarse aggregates, and for the 3D printing concrete with the coarse aggregates, due to the fact that the aggregate particle size is large and the aggregate shape is irregular, when a desktop printer is used for printing, the problems of blockage of the aggregates and small size of a printing head can occur. Therefore, there is no method for testing and characterizing the working performance of 3D printed concrete containing coarse aggregate for reference.
Disclosure of Invention
Aiming at the defects, the invention provides a device and a method for testing the extrudability and the mechanical property in a fresh mixing state of 3D printed concrete, which are suitable for concrete materials with the aggregate particle size of 0-31.5mm, can simulate the extrusion process of the printed concrete, evaluate the extrudability of the printed concrete, the rheological parameters and the early mechanical property of the concrete, and provide parameters for the subsequent constructability evaluation of the 3D printed concrete.
The technical scheme of the invention is as follows:
A3D printing concrete extrudability and freshly-mixed state mechanical property testing device comprises a press machine, an extrusion device, a movable trolley, a control system and a camera, wherein the press machine is of a door-type structure, a lower pressing rod is arranged in the center of the top of the press machine, the extrusion device comprises a push rod, a charging barrel, an extrusion barrel and a support frame, the charging barrel and the extrusion barrel are of cylindrical structures, fixing rings which protrude outwards are arranged on the lower edge of the charging barrel and the upper edge of the extrusion barrel, the support frame comprises a circular support table and three support rods which are obliquely fixed on the ground, the circular center of the support table is used for placing the extrusion barrel, the charging barrel and the extrusion barrel are respectively positioned above and below the support frame and are fixed on the support table through the fixing rings and bolts, the upper end and the lower end of the push rod are respectively connected with an upper circular disc and a lower, the lower end part of the extrusion cylinder is provided with a buckle, the extrusion device is positioned under the lower pressure rod and on a central line, the movable trolley is positioned under the extrusion cylinder, and is spaced from the lower end of the extrusion cylinder by a certain distance, the installation height of the camera is consistent with the height of the charging cylinder, the control system comprises a computer and a display screen, the computer is provided with 3D printing concrete rheological property analysis and calculation software, the charging barrel and the extruding barrel are used for filling 3D printing concrete, the press machine is connected with the control system and receives an instruction sent by the control system, the lower pressing rod descends and presses the push rod down to enable the push rod to press the filled 3D printing concrete in the charging barrel, and calculating the rheological property of the 3D printing concrete material according to the extrusion pressure F of the control system, wherein the aggregate particle size of the 3D printing concrete is 0-31.5 mm.
The movable trolley is provided with a top plate and a bottom plate, the upper surface of the top plate is a smooth plane, the top plate and the bottom plate are square plates, the length or the width of each square plate is not more than the distance between two adjacent supporting rods, a spring is arranged between the top plate and the bottom plate and used for adjusting the distance between the top plate and the bottom plate, and the movable trolley is provided with an electric motor and is controlled by a remote controller.
The charging barrel and the extruding barrel are made of PCV materials, the inner diameter of the charging barrel is larger than that of the extruding barrel, the inner diameter D of the charging barrel is 50mm-400mm, the inner diameter D of the extruding barrel is 20mm-180mm, the length L of the extruding barrel is 100mm-400mm, and the buckle is a round metal sheet.
The diameter of the lower disc is smaller than the inner diameter of the charging barrel, and a sealing ring is arranged at the edge of the lower disc.
A method for testing the extrudability and the mechanical property of fresh-mixed concrete by 3D printing comprises the following steps:
s1: wetting the inner walls of the charging barrel and the extruding barrel, the lower disc of the push rod and the upper surface of a top plate of the movable trolley;
s2: installing an extrusion device, keeping the central line of the extrusion device consistent with the central line of a lower press rod of the press machine, and fastening the lower end of an extrusion cylinder by a buckle;
s3: adjusting the height of the movable trolley to enable the distance between the trolley top plate and the extrusion cylinder to be d +/-10 mm of the inner diameter of the extrusion cylinder;
s4: installing a camera, enabling the height of the camera to be consistent with that of the charging barrel, and starting a timing shooting mode;
s5: filling a 3D printing concrete material into the charging barrel until the charging barrel and the extrusion barrel are filled with the concrete material;
s6: inserting a lower disc at the lower end of a push rod into the charging barrel, controlling a lower pressing rod of a press machine to descend through a control system, contacting with the push rod and pressing the push rod downwards, and prepressing fresh concrete in the charging barrel to enable concrete materials in the charging barrel and the extruding barrel to reach a compact state;
s7: adjusting a control system, selecting displacement control, selecting a certain extrusion speed V, simultaneously opening a buckle at the lower end of an extrusion cylinder, and extruding concrete materials at a constant speed;
s8: after the concrete material is extruded stably, starting a motor of the movable trolley to ensure that the movable trolley keeps a certain speed and moves at a constant speed;
s9: observing the numerical value of the extrusion pressure F of the control system, and recording the extrusion pressure F1 and the extrusion speed V1 when the extrusion pressure F begins to stabilize;
s10: changing different extrusion speeds V2, V3 and V4, and repeating the steps S7-S9 for three times to respectively obtain F2, F3 and F4;
s11: calculating to obtain extrusion pressure P according to different extrusion pressures F and the inner diameter D of the extrusion cylinder, evaluating the extrudability of the 3D printing concrete material according to the extrusion pressure P value at the fixed extrusion speed V, and obtaining the critical extrusion pressure P with the extrudability evaluated as easy, medium and difficulteAnd Ph；
S12: the extrusion speeds V1, V2, V3 and V4 and the pressures F1, F2, F3 and F4 obtained in the test are respectively substituted into the formulas:
wherein sigma represents the volume yield stress, α and β are constant parameters, and the rheological parameter shear yield stress tau of the 3D printed concrete material is obtained by solving through four simultaneous equations;
s13: removing the bolts, replacing the charging barrel with a charging barrel with the inner diameter D of 100mm and the height of 200mm, fastening the lower end of the extrusion barrel in a buckling manner, adding newly-mixed 3D printing concrete into the charging barrel, and inserting the push rod into the charging barrel again;
s14: starting a control system, pressing a push rod by a pressing rod until the concrete in the charging barrel is compacted and reaches a certain height, and closing the control system;
s15: after standing for a specified age, dismantling the bolts, vertically and slowly lifting the charging barrel, restarting a control system, selecting displacement control, selecting a certain extrusion speed V, and pressing down a push rod by a pressing rod until the fresh concrete is obviously damaged;
s16: and processing the pictures shot by the camera and the stress change by adopting 3D printed concrete rheological property analysis and calculation software, establishing a stress-strain curve of the fresh concrete, and obtaining the strength of the fresh concrete after standing for different ages.
The extrusion pressure F of the press is 0-10kN, the pressurization can be controlled by the displacement of a control system, and the extrusion speed V is 0-50 mm/min.
The particle size of the aggregate in the concrete material of the step S5 is 0-31.5 mm.
V in the step S7 is 1-20 mm/S, and the movement speed of the trolley in the step S8 is the same as the extrusion speed V.
The specified age time range of step S15 is such that the extrusion speed V is 0.1mm/S to 10mm/S before the initial setting of the concrete.
The 3D printed concrete performance testing device comprises a press machine, an extruding device, a movable trolley, a control system and a camera, wherein the extruding device comprises a push rod, a charging barrel, an extruding barrel and a supporting frame, the extruding device is positioned below a lower pressing rod of the press machine, the movable trolley is positioned below the extruding device, the press machine is controlled by the control system, and the lower pressing rod presses the push rod downwards to enable 3D printed concrete to be extruded from the extruding barrel and fall on the movable trolley which runs at a constant speed. The movement of the extrusion head was simulated by the planar movement of the movable carriage, and the extrudability of the concrete material was evaluated by varying the extrusion pressure and extrusion speed. Through a calculation formula, the rheological parameter shear yield stress of the 3D printed concrete material can be calculated for evaluating the working performance of the 3D printed concrete, and the deformation of the material is monitored through a camera and 3D printed concrete rheological performance analysis and calculation software (DIC software), so that the early stress-strain law of the 3D printed concrete is obtained and the early mechanical property of the 3D printed concrete is evaluated.
Compared with the prior art, the method can simulate the extrusion process of 3D printed concrete, evaluate the extrudability of the concrete material, obtain the rheological parameters and the early mechanical property of the 3D printed concrete, is suitable for the extrusion simulation and the workability test of the 3D printed concrete material with the aggregate particle size of 0-31.5mm, can be used for evaluating the early performance of the 3D printed concrete material, provides reference indexes for the design of the mix proportion of the 3D printed concrete and provides parameters for the subsequent constructability evaluation of the 3D printed concrete. The testing device can make up the vacancy in the prior art and provide a technical foundation for the development of 3D printed concrete.
Drawings
FIG. 1 is a front view of a performance testing apparatus of the present invention;
FIG. 2 is an enlarged view of the cartridge of the present invention;
fig. 3 is an enlarged view of the movable cart of the present invention.
Detailed Description
The conception, the specific structure and the technical effects of the present invention will be further described with reference to the accompanying drawings to fully understand the objects, the features and the effects of the present invention.
Referring to fig. 1 to 3, the device for testing the extrudability and the mechanical property of the freshly mixed concrete in the 3D printing process comprises a press machine 10, an extruding device 20, a movable trolley 30, a control system 40 and a camera. The press 10 is of a gate type structure, and a lower pressing rod 11 is arranged in the center of the press 10. The extruding device 20 comprises a push rod 21, a charging barrel 22, an extruding barrel 23 and a supporting frame 24, wherein the charging barrel 22 and the extruding barrel 23 are both of cylindrical structures, the charging barrel 22 and the extruding barrel 23 are both made of PCV materials, the inner diameter D of the charging barrel 22 is 100mm, the height of the charging barrel is 300mm, the inner diameter D of the extruding barrel 23 is 50mm, and each set of device is provided with 2-4 extruding barrels 23 with different inner diameter sizes. Referring to fig. 2, the lower edge of the charging barrel 22 and the upper edge of the extruding barrel 23 are provided with fixing rings 221 protruding outwards, and the fixing rings 221 are circumferentially provided with four screw holes for screwing in bolts 222 for fixing.
The supporting frame 24 includes an annular supporting platform 241 and three supporting rods 242 obliquely fixed on the ground, the supporting platform 241 and the supporting rods 242 are made of iron, four screw holes are formed in the circumferential direction of the supporting platform 241, and the positions of the screw holes correspond to those of the screw holes in the fixing ring 221. The supporting table 241 has an outer diameter of 200mm and an inner diameter of the outer diameter of the extruding cylinder 23, the center of the supporting table is used for inserting the extruding cylinder 23, the charging cylinder 22 and the extruding cylinder 23 are respectively positioned above and below the supporting frame 24, and the supporting table 241 is fixed on the supporting table 241 through the fixing ring 221 and the bolt 222. The lower end of the extruding cylinder 23 is provided with a buckle 231, the buckle 231 is a round metal sheet, the thickness is 5mm, the diameter is 100mm, and the outer diameter is the same as that of the extruding cylinder 23. The charging cylinder 22 and the extruding cylinder 23 are used to fill 3D printed concrete, which is charged from the upper portion of the charging cylinder 22 and extruded from the lower portion of the extruding cylinder 23, for testing the performance of the concrete.
The upper end and the lower end of the push rod 21 are respectively connected with an upper disc 211 and a lower disc 212, the diameter of the upper disc 211 is 120mm and is 10mm-20mm larger than the diameter of the lower end part of a lower pressure rod 11 of the press machine 10, the lower disc 212 is inserted into the charging barrel 22, the diameter of the lower disc 212 is 5mm-10mm smaller than the inner diameter of the charging barrel 22, and the edge of the lower disc 212 is provided with a rubber or soft plastic sealing ring to form sealing with the inner wall of the charging barrel 22. The extruding device 20 is positioned under the lower pressing rod 11 and on a central line, and the movable trolley 30 is positioned under the extruding cylinder 23 and is spaced from the lower end of the extruding cylinder 23 by a certain distance. The camera is high definition camera, and its bottom installation tripod for adjust the height of camera, during the experiment, the mounting height of camera and charging barrel 22 highly uniform to open regularly and shoot the mode, be used for the stress variation under the record concrete compression state.
The movable trolley 30 is made of iron or aluminum alloy and is provided with a top plate 31, a bottom plate 32 and four rollers, the upper surface of the top plate 31 is a smooth plane, a spring 33 is arranged between the top plate 31 and the bottom plate 32, and the spring 33 is used for adjusting the distance between the top plate 31 and the bottom plate 32 and controlling the distance between the upper surface of the top plate 31 and the lower end of the extruding cylinder 23. The movable trolley 30 is equipped with an electric motor and is controlled by a remote controller. The maximum size of the top plate 31 from the ground is 400mm, and the top plate 31 and the bottom plate 32 are both rectangular plates with the size of 600mmx350mm, and the length and the width of each rectangular plate do not exceed the distance between two adjacent supporting rods 242, so that the movable trolley 30 can move between two adjacent supporting rods 242 conveniently.
The control system 40 comprises a computer and a display screen, 3D printing concrete rheological property analysis and calculation software (DIC software) is installed on the computer, the press machine 10 is connected with the control system 40, and receives an instruction sent by the control system 40, the pressing rod 11 descends and presses the push rod 21 downwards, and the push rod 21 presses the filled 3D printing concrete downwards in the charging barrel 22. The extrusion pressure F of the press machine 10 is 0-10kN, the pressurization can be controlled through the displacement of the control system 40, the extrusion speed V is 0-50mm/min, and the rheological property of the concrete material is calculated according to the extrusion pressure F of the control system 40. The testing device can be used for detecting the aggregate particle size in the concrete material to be 0-31.5mm, and is suitable for detecting the 3D printed concrete material containing coarse aggregate.
The invention discloses a method for testing the extrudability and the mechanical property of fresh-mixed concrete by 3D printing, which comprises the following steps:
s1: wetting the inner walls of the charging barrel 22 and the extruding barrel 23, the lower disc 212 of the push rod 21 and the upper surface of the top plate 31 of the movable trolley 30;
s2: installing the extruding device 20, keeping the central line of the extruding device 20 consistent with the central line of the lower press rod 11 of the press machine 10, and fastening the buckle 231 at the lower end of the extruding cylinder 23;
s3: adjusting the height of the movable trolley 30 to ensure that the distance between the trolley top plate 31 and the extrusion cylinder 23 is 110 mm;
s4: installing a camera, enabling the height of the camera to be consistent with that of the charging barrel 22, and starting a timing shooting mode;
s5: filling the charging barrel 22 with a 3D printing concrete material until the charging barrel 22 and the extruding barrel 23 are filled with the concrete material;
s6: inserting the lower disc 212 at the lower end of the push rod 21 into the charging barrel 22, controlling the lower pressing rod 11 of the press machine 10 to descend through the control system 40, contacting with the push rod 21 and pressing down the push rod 21, and pre-pressing the fresh concrete in the charging barrel 22 to enable the concrete materials in the charging barrel 22 and the extrusion barrel 23 to reach a compact state;
s7: the control system 40 is controlled, displacement control is selected, a certain extrusion speed V1 is selected to be 2.5mm/s, meanwhile, the buckle 231 at the lower end of the extrusion cylinder 23 is opened, and concrete materials are extruded at a constant speed;
s8: after the concrete material is extruded stably, starting a motor of the movable trolley 30 to ensure that the movable trolley 30 keeps a certain speed and moves at a constant speed, wherein the moving speed of the trolley is 2.5 mm/s;
s9: observing the value of the extrusion pressure F of the control system 40, when the extrusion pressure F starts to stabilize, recording the pressure F1 at this time as 4.96 kN;
s10: changing different extrusion speeds, wherein V2 is 5mm/S, V3 is 7.5mm/S, and V4 is 10mm/S, repeating steps S7-S9 three times to obtain F2 is 8.08kN, F3 is 10.26kN, and F4 is 15.33kN, respectively;
s11: the extrusion pressure P can be calculated according to the extrusion pressure F and the inner diameter D of the extrusion cylinder 23, the extrudability of the 3D printing concrete material is evaluated according to the extrusion pressure P value at the fixed extrusion speed V, and the critical extrusion pressure P with the extrudability evaluated as easy, medium and difficult is obtainedeAnd Ph(ii) a Wherein is less than PeFor extrudability evaluation as easy, between PeAnd PhBetween is extrudable and evaluated as being greater than PhThe extrudability was evaluated as difficult;
the test found that the critical extrusion pressure value P is such that the extrusion speed V is 5mm/se＝1200kPa，Ph5000kPa, the aggregate particle size of the concrete material used in this example was 0 to 25mm, the water-cement ratio was 0.35, the sand ratio was 0.4, the inner diameter d of the extrusion cylinder 23 was 100mm, and the extrusion speed V was 5mm/s, the extrusion force obtained was 8.08kN, and the extrusion pressure was 1029kPa by calculation, so the extrudability was evaluated as easy;
s12: the extrusion speeds V1, V2, V3 and V4 and the pressures F1, F2, F3 and F4 obtained in the test are respectively substituted into the formulas:
wherein sigma represents the volume yield stress, α and β are constant parameters, and the rheological parameter shear yield stress tau of the 3D printed concrete material is obtained by solving through four simultaneous equations, wherein the shear yield stress tau is 128.55 Pa;
s13: removing the bolt 222, replacing the charging cylinder 22 with the inner diameter D of 100mm and the height of 200mm, fastening the buckle 231 at the lower end of the extruding cylinder 23, adding the freshly mixed 3D printing concrete into the charging cylinder 22, and inserting the push rod 21 into the charging cylinder 22 again;
s14: starting the control system 40, pressing the push rod 21 downwards by the pressing rod 11 until the concrete in the charging barrel 22 is compact and reaches the height of 200mm, and closing the control system 40;
s15: after standing for 1 hour, removing the bolts, vertically and slowly lifting the charging barrel 22, restarting the control system 40, selecting displacement control, selecting the extrusion speed V to be 5mm/s, and pressing the push rod 21 downwards by the pressing rod 11 until the fresh concrete is obviously damaged;
s16: and processing the pictures shot by the camera and the stress change by adopting 3D printed concrete rheological property analysis and calculation software, establishing a stress-strain curve of the fresh concrete, and obtaining the strength of the fresh concrete after standing for 1 hour, wherein the strength is 15 kPa.
The method is suitable for extrusion simulation and workability test of the 3D printing concrete material with the aggregate particle size of 0-31.5mm, can simulate the extrusion process of the 3D printing concrete, evaluate the extrudability of the concrete material, obtain the rheological parameters and the early mechanical property of the 3D printing concrete, evaluate the early performance of the 3D printing concrete material, provide reference indexes for the design of the mixing ratio of the 3D printing concrete and provide parameters for the subsequent constructability evaluation of the 3D printing concrete. The device and the method for testing the extrudability and the mechanical property of the newly-mixed concrete in the 3D printing state can make up for the vacancy in the prior art and provide a technical basis for the development of the 3D printing concrete.
The above disclosure is only an example of the present invention, but the present invention is not limited thereto, and any variations that can be made by those skilled in the art should fall within the scope of the present invention.
Claims (9)
1. The device for testing the extrudability and the mechanical property of the freshly mixed concrete in the 3D printing mode is characterized by comprising a press machine (10), an extruding device (20), a movable trolley (30), a control system (40) and a camera, wherein the press machine (10) is of a door-type structure, a lower pressing rod (11) is arranged in the center of the top of the press machine (10), the extruding device (20) comprises a push rod (21), a charging barrel (22), an extruding barrel (23) and a supporting frame (24), the charging barrel (22) and the extruding barrel (23) are of cylinder structures, fixing rings (221) protruding outwards are arranged on the lower edge of the charging barrel (22) and the upper edge of the extruding barrel (23), the supporting frame (24) comprises a circular supporting table (241) and three supporting rods (242) obliquely fixed on the ground, and the center of the circular ring of the supporting table (241) is used for placing the extruding barrel (23), the charging barrel (22) and the extruding barrel (23) are respectively positioned above and below the supporting frame (24) and are fixed on the supporting table (241) through a fixing ring (221) and a bolt (222), the upper end and the lower end of the push rod (21) are respectively connected with an upper disc (211) and a lower disc (212), the lower disc (212) is inserted into the charging barrel (22), the lower end part of the extruding barrel (23) is provided with a buckle (231), the extruding device (20) is positioned under the lower pressing rod (11) and is positioned on a central line, the movable trolley (30) is placed under the extruding barrel (23) and is spaced from the lower end of the extruding barrel (23) for a certain distance, the installation height of the camera is consistent with the height of the charging barrel (22), the control system (40) comprises a computer and a display screen, and the computer is provided with 3D printing concrete rheological property analyzing and calculating software, the charging barrel (22) and the extruding barrel (23) are used for filling 3D printing concrete, the press machine (10) is connected with the control system (40), receives an instruction sent by the control system (40), descends the pressing rod (11) and presses the pushing rod (21) downwards, the pushing rod (21) presses the filled 3D printing concrete downwards in the charging barrel (22), the rheological property of the 3D printing concrete material is obtained through calculation according to the extruding pressure F of the control system (40), and the aggregate particle size of the 3D printing concrete is 0-31.5 mm.
2. The testing device as claimed in claim 1, wherein the movable trolley (30) is provided with a top plate (31) and a bottom plate (32), the upper surface of the top plate (31) is a smooth plane, the top plate (31) and the bottom plate (32) are square plates, the length or width of each square plate is not more than the distance between two adjacent supporting rods (242), a spring (33) is arranged between the top plate (31) and the bottom plate (32), the spring (33) is used for adjusting the distance between the top plate (31) and the bottom plate (32), and the movable trolley (30) is provided with an electric motor and is controlled by a remote controller.
3. The testing device according to claim 1, wherein the charging barrel (22) and the extruding barrel (23) are made of PCV material, the inner diameter of the charging barrel (22) is larger than that of the extruding barrel (23), the inner diameter D of the charging barrel (22) is 50mm-400mm, the inner diameter D of the extruding barrel (23) is 20mm-180mm, the length L of the extruding barrel (23) is 100mm-400mm, and the buckle (231) is a circular metal sheet.
4. The testing device according to claim 1, characterized in that the diameter of the lower disc (212) is smaller than the inner diameter of the cartridge (22), and the edge of the lower disc (212) is provided with a sealing ring.
5. A method for testing the extrudability and the mechanical property of fresh-mixed concrete by 3D printing is characterized by comprising the following steps:
s1: wetting the inner walls of the charging cylinder (22) and the extruding cylinder (23), the lower disc (212) of the push rod (21) and the upper surface of the top plate (31) of the movable trolley (30);
s2: installing an extrusion device (20), keeping the central line of the extrusion device (20) consistent with the central line of a lower press rod (11) of the press machine (10), and fastening a buckle (231) at the lower end of an extrusion cylinder (23);
s3: the height of the movable trolley (30) is adjusted to ensure that the distance between the trolley top plate (31) and the extrusion cylinder (23) is d +/-10 mm of the inner diameter of the extrusion cylinder (23);
s4: installing a camera, enabling the height of the camera to be consistent with that of the charging barrel (22), and starting a timing shooting mode;
s5: filling 3D printing concrete materials into the charging barrel (22) until the charging barrel (22) and the extruding barrel (23) are filled with the concrete materials;
s6: inserting a lower disc (212) at the lower end of a push rod (21) into a charging barrel (22), controlling a lower press rod (11) of a press machine (10) to descend through a control system (40), contacting with the push rod (21) and pressing down the push rod (21), and pre-pressing fresh concrete in the charging barrel to enable concrete materials in the charging barrel (22) and an extrusion barrel (23) to reach a compact state;
s7: the adjusting control system (40) selects displacement control, selects a certain extrusion speed V, and simultaneously opens a buckle (231) at the lower end of the extrusion cylinder (23) to extrude the concrete material at a constant speed;
s8: after the concrete material is extruded stably, a motor of the movable trolley (30) is started to ensure that the movable trolley (30) moves at a constant speed;
s9: observing the numerical value of the extrusion pressure F of the control system (40), and recording the extrusion pressure F1 and the extrusion speed V1 when the extrusion pressure F begins to stabilize;
s10: changing different extrusion speeds V2, V3 and V4, and repeating the steps S7-S9 for three times to respectively obtain F2, F3 and F4;
s11: the extrusion pressure P can be calculated according to different extrusion pressures F and the inner diameter D of the extrusion cylinder (23), the extrudability of the 3D printing concrete material is evaluated according to the extrusion pressure P value at the fixed extrusion speed V, and the obtained extrusion ability is evaluated as the easy, medium and difficult critical extrusion pressure PeAnd Ph；
S12: the extrusion speeds V1, V2, V3 and V4 and the pressures F1, F2, F3 and F4 obtained in the test are respectively substituted into the formulas:
wherein sigma represents the volume yield stress, α and β are constant parameters, and the rheological parameter shear yield stress tau of the 3D printed concrete material is obtained by solving through four simultaneous equations;
s13: removing the bolt (222), replacing the charging cylinder (22) with a charging cylinder (22) with the inner diameter D of 100mm and the height of 200mm, fastening a buckle (231) at the lower end of the extruding cylinder (23), adding newly-mixed 3D printing concrete into the charging cylinder (22), and inserting the push rod (21) into the charging cylinder (22) again;
s14: starting the control system (40), pressing the push rod (21) downwards by the pressing rod (11) until the concrete in the charging barrel (22) is compact and reaches a certain height, and closing the control system (40);
s15: after standing for a specified age, removing the bolts, vertically and slowly lifting the charging barrel (22), restarting the control system (40), selecting displacement control, selecting a certain extrusion speed V, and pressing down the push rod (21) by the pressing down rod (11) until the fresh concrete is obviously damaged;
s16: and processing the pictures shot by the camera and the stress change by adopting 3D printed concrete rheological property analysis and calculation software, establishing a stress-strain curve of the fresh concrete, and obtaining the strength of the fresh concrete after standing for different ages.
6. Test method according to claim 5, characterized in that the extrusion pressure F of the press (10) is 0-10kN, the pressing can be controlled by displacement of the control system (40), and the extrusion speed V is 0-50 mm/min.
7. The test method as claimed in claim 5, wherein the aggregate in the concrete material of the step S5 has a particle size of 0-31.5 mm.
8. The test method according to claim 5, wherein V in the step S7 is 1-20 mm/S, and the moving speed of the dolly in the step S8 is the same as the extrusion speed V.
9. The test method according to claim 5, wherein the specified age time range of step S15 is 0.1mm/S to 10mm/S for the extrusion speed V before initial setting of the concrete.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111811934A (en) * | 2020-06-09 | 2020-10-23 | 湖北省四极新材料有限公司 | Quantitative evaluation method and device for concrete workability analysis based on bottom resistance |
| CN114102797A (en) * | 2021-12-27 | 2022-03-01 | 中交第一公路勘察设计研究院有限公司 | Quantification device for printing performance of 3D printing building material and using method thereof |
| CN115201066A (en) * | 2022-07-26 | 2022-10-18 | 东北大学 | 3D printing performance evaluation test method for deep hard rock similar material |
| CN117309879A (en) * | 2023-09-28 | 2023-12-29 | 安徽空间智筑技术有限公司 | Building 3D printing concrete work performance test system and use method |
| CN119862682A (en) * | 2024-11-25 | 2025-04-22 | 北京耐尔得智能科技有限公司 | Method for rapidly evaluating printability of 3D printing concrete based on torque feedback |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203949839U (en) * | 2014-06-03 | 2014-11-19 | 三一汽车制造有限公司 | A kind of flow graph |
| CN206733601U (en) * | 2016-12-28 | 2017-12-12 | 广东五维科技有限公司 | A 3D printer |
| US20170365365A1 (en) * | 2016-06-21 | 2017-12-21 | Raytheon Company | Additively Manufactured Concrete-Bearing Radiation Attenuation Structure |
| CN108548721A (en) * | 2018-03-29 | 2018-09-18 | 中铁四局集团有限公司 | Device and method for measuring bearing capacity and deformation of freshly mixed 3D printed concrete |
| CN108663247A (en) * | 2018-05-18 | 2018-10-16 | 东南大学 | A kind of wet base molding machine and its strength detecting method of 3D printing concrete |
| CN110243724A (en) * | 2019-05-31 | 2019-09-17 | 华中科技大学 | A kind of 3D printing mortar extrusion performance quantitative testing device and method |
-
2019
- 2019-12-30 CN CN201911399112.8A patent/CN111175184A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203949839U (en) * | 2014-06-03 | 2014-11-19 | 三一汽车制造有限公司 | A kind of flow graph |
| US20170365365A1 (en) * | 2016-06-21 | 2017-12-21 | Raytheon Company | Additively Manufactured Concrete-Bearing Radiation Attenuation Structure |
| CN206733601U (en) * | 2016-12-28 | 2017-12-12 | 广东五维科技有限公司 | A 3D printer |
| CN108548721A (en) * | 2018-03-29 | 2018-09-18 | 中铁四局集团有限公司 | Device and method for measuring bearing capacity and deformation of freshly mixed 3D printed concrete |
| CN108663247A (en) * | 2018-05-18 | 2018-10-16 | 东南大学 | A kind of wet base molding machine and its strength detecting method of 3D printing concrete |
| CN110243724A (en) * | 2019-05-31 | 2019-09-17 | 华中科技大学 | A kind of 3D printing mortar extrusion performance quantitative testing device and method |
Non-Patent Citations (2)
| Title |
|---|
| STEFAN CHAVES FIGUEIREDO ET AL: "An approach to develop printable strain hardening cementitious composites", 《MATERIALS AND DESIGN》 * |
| YU CHEN ET AL: "Limestone and Calcined Clay-Based Sustainable Cementitious Materials for 3D Concrete Printing:A Fundamental Study of Extrudability and Early-Age Strength Development", 《APPLIED SCIENCES》 * |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111811934A (en) * | 2020-06-09 | 2020-10-23 | 湖北省四极新材料有限公司 | Quantitative evaluation method and device for concrete workability analysis based on bottom resistance |
| CN114102797A (en) * | 2021-12-27 | 2022-03-01 | 中交第一公路勘察设计研究院有限公司 | Quantification device for printing performance of 3D printing building material and using method thereof |
| CN115201066A (en) * | 2022-07-26 | 2022-10-18 | 东北大学 | 3D printing performance evaluation test method for deep hard rock similar material |
| CN117309879A (en) * | 2023-09-28 | 2023-12-29 | 安徽空间智筑技术有限公司 | Building 3D printing concrete work performance test system and use method |
| CN117309879B (en) * | 2023-09-28 | 2024-02-27 | 安徽空间智筑技术有限公司 | Building 3D printing concrete work performance test system and use method |
| CN119862682A (en) * | 2024-11-25 | 2025-04-22 | 北京耐尔得智能科技有限公司 | Method for rapidly evaluating printability of 3D printing concrete based on torque feedback |
| CN119862682B (en) * | 2024-11-25 | 2025-07-18 | 北京耐尔得智能科技有限公司 | A method for quickly evaluating the printability of 3D printed concrete based on torque feedback |
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