FR2773340A1 - The preparation of new concrete elements such as paving stones, flagstones, decorative modules etc., using a modified concrete material - Google Patents

Abstract

The preparation of a new type of paving stone from a modified plastic concrete material of a specified color with irregular patches introduced with a concrete of a different color, using a deformable plastic mold. The concrete elements (1) are prepared as follows :- -preparation of a mold with at least one cast impression (9) in a deformable plastic material, having a base wall (6) which corresponds to the visible face and a mold opening by extraction ; -positioning of the mold for gravity filling ; -deposition, in an irregular manner, of one or more patches of concrete (10) of a different color from the bulk material, on the wall (6) without covering the entire wall ; -filling of the mold with the main plastic concrete material by vibration of the mold and leveling ; -storage of the filled mold for one day followed by de-molding. Independent claims are also included for the molded elements obtained and the molds for effecting the operation.

Description

PROCESS FOR PRODUCING CONCRETE ELEMENTS WITH EFFECT
SURFACE, MATERIAL FOR ITS IMPLEMENTATION AND ELEMENTS
THUS OBTAINED
The present invention relates to the production of concrete elements, such as for example pavers, slabs or the like for coating exterior surfaces, and more generally any concrete element intended for coating, for the production of modules decorative, green and urban spaces, basins, tubs, planters, street furniture, bollards, curbs, etc ..., both outdoors and indoors.

 The invention will be described below more specifically in its application to the production of paving stones, in particular sidewalks.

 For a very long time, it has been thought to cover the ground, in an urban environment, with terracotta pavers, some of which have a particularly decorative flamed appearance, obtained, voluntarily or not, during cooking, generally by contact with the flames.

 Little by little, however, a disaffection with these pavers has manifested itself in particular due to aging and color problems, but also by the desire for new, more modern products. The manufacture of such terracotta pavers has almost disappeared and we have turned to alternative products such as concrete pavers or natural stone.

 However, these products do not have the qualities of traditional terracotta pavers.

 Vibrated and pressed concrete pavers, whether they are self-locking or not, have a particular aspect, coming from their technique of realization and their composition, which is very different from that of terracotta pavers remarkable by their surface aspect to both relatively smooth while revealing irregularities and by their flamed appearance for some.

 These vibrated and pressed concrete pavers are mostly laid on a bed of sand and it is not possible to joint them with a mortar. The laitance of the mortar is indeed encrusted on these pavers, which is not the case for terracotta pavers, the jointing of which contributes to the general aesthetic effect.

 Natural stone products constitute the top of the range, but their cost is high and soiling can also become embedded there as for the other aforementioned products.

 The aim of the present invention is to propose a new type of concrete paver having the charm of the old terracotta pavers, in particular the nuance produced by the art of fire.

To this end, the invention relates to a method for producing concrete elements with surface effect, characterized by the following steps
- production of a mold with at least one imprint, made of plastic
deformable, from one or more original elements or
counter-types, said imprint having at least one bottom wall
corresponding to a visible face of the element to be produced and an opening
demoulding by extraction,
- positioning of the mold for filling the imprint (s)
by gravity,
- depositing on said bottom wall, in an irregular manner, of one or
several piles of concrete called task, of a determined color, so as to
do not cover the entire surface of said wall, then,
- filling the mold with plastic concrete known as dominant concrete,
in a color different from that of task concrete, with
mold vibration and leveling, and
- storage of the filled mold for about a day then demolding
of the element (s).

 The products thus obtained have an appearance and a surface finish quite similar to those, for example, of traditional terracotta pavers, and furthermore present on the surface effects of color stains very substantially reminiscent of the flamed effects of certain pavers.

 The invention also relates to the various elements or products obtained in accordance with the above process, whatever their shapes, dimensions and destinations, as well as the specific molds necessary for obtaining them.

Other characteristics and advantages of the invention will emerge from the description which follows of an embodiment of the method, description given by way of example only and with reference to the appended drawing in which
FIG. 1 is a perspective view of a paver, of the old terracotta paver type, produced in accordance with the method of the invention,
FIG. 2 is a perspective view of a multi-cavity mold for implementing the method, and
- Figure 3 is a diagram illustrating the principle of embodiment, according to the invention, of a three-dimensional element with several faces having effects of the flamed type.

 In Figure 1, there is shown a block made according to the method of the invention.

 This paver is for example of shape and dimensions corresponding to traditional terracotta pavers, used in the past for paving sidewalks, namely a paver of square shape, 1 2.5 cm in side and 5 cm thick.

 This paver comprises, like said traditional pavers, an upper face 1 slightly curved and relatively smooth while presenting surface irregularities, in particular local gaps or indentations shown at 2 in FIG. 1, irregular in shape, dimensions and distribution over the surface, exactly as seen on terracotta pavers.

 The periphery of the visible upper face 1 of the paver also has, like traditional pavers, an irregular rim recessed with respect to the lateral faces 3, so as to provide a small aesthetic projection 4.

 The lateral faces 3 are slightly inclined for reasons of demolding.

 According to another essential characteristic of the paver of the invention, it mainly comprises on its visible face 1 task effects represented in 5, of a color different from that of the rest of the surface of said face 1.

 These tasks 5 may extend slightly over some of the side faces 3.

 The first step in the process for manufacturing such pavers consists in making a mold made of deformable, flexible plastic, polyurethane, silicone or the like.

 The mold comprises one or preferably several imprints side by side as shown in FIG. 2.

 The mold shown comprises a bottom wall 6, frame walls 7 and interior partitions 8 defining compartments or cavities 9 with opening in the upper part, the bottom 6 corresponding to the visible face of the pavers to be molded.

 The mold is itself obtained by molding from a form in which are placed traditional pavers of terracotta or counter-types.

 The production of the mold is entirely conventional from commercial products.

 Thus, the faces (6, 8) of the mold take the imprint of surface irregularities (not shown in Figure 2) of traditional pavers and the sides 8 are slightly inclined and allow easy demolding.

 The mold is placed as illustrated in FIG. 2 for filling by gravity.

 Firstly, and after spraying with a release agent, small deposits 10 of a first colored concrete, called task concrete, are deposited in each cavity 9, by hand or by any suitable mechanical device.

One or more clusters 10 are thus placed in each imprint, in an irregular or random manner, the clusters being of the same size or not, agglomerated or slightly dispersed or exploded, at the option of the operator for example.

 These clusters 10 do not cover the entire surface of the bottom 6.

 Then, a second colored concrete, called dominant concrete, is poured into the cavities 9 so as to completely fill them.

 During filling, the mold, placed on a vibrating table is subjected to vibration, for two minutes for example, and the mold is leveled.

 The color of the dominant concrete is different from that of task concrete 1 0, which thus forms inclusions in the dominant mass of the other concrete.

 The mold thus filled is stored in this position for several hours, for example a day, then the molded elements or products are extracted, the extraction being facilitated by the relatively flexible and deformable material of the mold.

 Extraction can be manual, automated or semi-automated, such as filling the mold.

 The small clumps of concrete 10 (5, Figure 1) remain individualized and do not melt in the mass of the dominant concrete, their visible outline on face 1 of the paving stone, while not being clean and sharp, is nevertheless clearly distinguished and irregularities in shape, size and distribution on the surface of face 1 are very variable from one block to another in the same mold.

 By way of example, the task concrete 10 may comprise large crushed siliceous pebbles of particle size 6/10, silica sand of particle size 0 / 1.2, crushed limestone of particle size 0/3, gray or white cement , various adjuvants including a water repellent and one or more dyes, for example a black dye and a brown iron oxide.

The proportions, as a percentage of the total dry weight, of the main constituents of such concrete are of the order of
45% for crushed pebbles
22% for silica sand
22% for crushed limestone
16% for cement.

 Furthermore, and still by way of example, the dominant concrete may include the same crushed pebbles, silica sand and crushed limestone as the task concrete, white cement and the same additives as well as one or more dyes different from those task concrete. In addition, advantageously, the dominant concrete comprises polypropylene fibers to bind the concrete particles, avoid micro-cracking and allow good hydration.

The proportions, as a percentage of the total dry weight, of the main constituents of such concrete are similar to those of other concrete, i.e. of the order of:
45% for crushed pebbles
22% for silica sand
22% for crushed limestone
16% for cement.

 Water is added to the above constituents at the rate of approximately 120 liters per m3 of mixture.

 The concretes used in the invention are plastic concretes which give the pavers an appearance and quite advantageous advantages compared to the concretes of traditional pavers or slabs.

 Indeed, traditional products, vibrated and pressed by machine are immediately removed from the mold. Their appearance is grainy while the products molded according to the invention, due to the nature of the mold, the nature of the concretes and the molding conditions, implying a storage time of 24 hours minimum before demolding, have a surface appearance. relatively smooth, with "defects" and irregularities similar to old traditional products.

 The pavers of the invention can thus be easily grouted with a cement mortar, which vibrated and pressed concrete products do not allow, as recalled in the preamble to the description.

 As also mentioned above, the method of the invention allows the production of all kinds of elements or products for outdoor or indoor use (surface coating, decorative objects, street furniture, planter, bins, curbs, bollards , etc ...).

 All or part of these products can be produced by implementing the process.

 FIG. 3 illustrates by way of example the procedure for producing task effects on several faces of a three-dimensional object, for example a frusto-conical terminal.

 In a suitable mold 11, several layers 12, 13, 14 are put in place, each consisting of two parts, one (15) of task concrete and the other (16) of dominant concrete. The establishment of each stratum is done as the realization of the paving stone of Figure 1.

 Of course, for the layers 13, 14, of which only the edge is visible, the task concrete 1 5 will be positioned at the edge, against the wall of the mold 11.

 Task effects will be visible on all sides of the molded bollard.

 Finally, the invention is obviously not limited to the embodiments shown and described above, but on the contrary covers all the variants thereof, both as regards the nature and the proportions of the constituents of the task concretes and dominant, identical or not, as regards the nature, shapes and dimensions of the mold, as well as the molding process.

Claims (7)

 1. Method for producing concrete elements with surface effect (1), characterized by the following steps  - Production of a mold with at least one imprint (9), in material  deformable plastic, from one or more original elements or  counter-types, said imprint (9) having at least one bottom wall  (6) corresponding to a visible face of the element to be produced and a  demolding opening by extraction,  - positioning of the mold for filling the imprint (s)  (9) by gravity,  - depositing on said bottom wall (6), in an irregular manner, of one or  several piles (10) of so-called task concrete, of a determined color, of  so as not to cover the entire surface of said wall (6), then,  - filling the mold with plastic concrete known as dominant concrete,  in a color different from that of task concrete, with  mold vibration and leveling, and  - storage of the filled mold for about a day then demolding  of the element (s) (1).  2. Method according to claim 1, characterized in that the task concrete (10) comprises large crushed siliceous pebbles of grain size 6/10, silica sand of grain size 0 / 1.2, crushed limestone of grain size 0 / 3, gray or white cement, suitable adjuvants including a water repellent and one or more colorants.  3. Method according to claim 1, characterized in that the dominant concrete comprises large crushed siliceous pebbles of grain size 6/10, silica sand of grain size 0 / 1.2, crushed limestone of grain size 0/3, cement white, various additives including a water repellent, and one or more dyes and polypropylene fibers.  4. Method according to claims 2 or 3, characterized in that the proportions, as a percentage of the total dry weight, of the main constituents of the concrete are of the order of  45% for crushed pebbles  22% for silica sand  22% for crushed limestone  1 6% for cement.  5. Method according to claim 1, more particularly applied to the production of elements with several faces with task effects, characterized in that the mold imprint is filled by superimposed layers each comprising a task concrete (1 5) on a visible face of the element to be produced and a dominant concrete.  6. Molded elements produced in accordance with the method of any one of the preceding claims.  7. Mold for implementing the method according to any one of claims 1 to 5, characterized in that it comprises at least one imprint (9), made of deformable plastic, made from one or more elements originals or counter-types, said imprint (9) having at least one bottom wall (6) corresponding to a visible face of the element to be produced and a demolding opening.