process for manufacturing a calibrated concrete masonry block at a given height

Abstract

The invention relates to a method for manufacturing a masonry concrete block calibrated to a determined height, comprising steps of filling a mold placed on a vibrating press with a fresh mass concrete composition and compacting the mass concrete composition contained in the mold, the calibration of the masonry block being obtained by filling the mold with the mass concrete composition to a height corresponding to a range between 80 and 90% of the final height of the masonry block at the desired outlet from the oven and then pouring into the mold a second fresh concrete composition onto the compacted mass concrete composition to reach the desired final height of the masonry block and compacting the second fresh composition onto the mass composition.

Description

Title of the invention: method for manufacturing a concrete masonry block calibrated to a given height TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the field of manufacturing concrete masonry blocks (concrete blocks).

[0002] The invention relates more particularly to a method for manufacturing a concrete masonry block calibrated to a determined height, comprising a step of filling a mold placed on a vibrating press with a mass concrete composition in the fresh state and a step of compacting this mass concrete composition.

[0003] The manufacturing method is intended in particular, but not exclusively, for the manufacture of blocks to be coated and blocks to be coated. STATE OF THE ART

[0004] Concrete masonry blocks commonly have numerous irregularities on the surface due to the presence of more or less large aggregate particles, heterogeneity in the filling of the mold cells during the filling and pre-vibration phase, which is difficult to control, and due to burrs caused during their manufacture.

[0005] Such irregularities prevent satisfactory flatness and parallelism of the lower and upper faces of the masonry blocks from being obtained. However, certain techniques for laying concrete masonry blocks, and in particular the thin-joint technique for laying concrete blocks, which is economical in cement, require precise dimensioning, in particular a precise height measurement. This need for precise height dimensioning imposes dimensional manufacturing tolerances.

[0006] Examples of desired tolerances are given in the table extracted from the NF Certification Reference, part 2 “NF Certification Rules for Concrete Blocks of Common and Lightweight Aggregates” below. Product designation Tolerance class Tolerances {mmj Blocks to be coated for masonry 01 MM Facing blocks for masonry &2 MM Blocks to be coated for 1st 83 (Mb LS) Blocks to be coated or facing for cdler 84 MM; I ~ width, width, height

[0007] Dimensional tolerances are tolerances of parallelism, flatness and homogeneity of height across all blocks. These are more or less difficult to achieve depending on the different tolerance classes (Di).

[0008] To achieve certain masonry block tolerance classes (e.g. D3, D4 in the table above), mechanical methods of removing material by "rectification" are used after molding and baking the masonry block. These methods involve removing material by machining or polishing or calibrating to achieve the desired height and flatness.

[0009] These methods of material removal present a high investment cost in equipment and especially in replacement of machining tools with always the risk of altering or weakening the concrete masonry blocks during their production.

[0010] Furthermore, given the importance of the surface condition of the masonry blocks and their irregularities, it is sometimes difficult to obtain, with this type of method, low dimensional tolerances, such as for example tolerance classes D3, D4.

[0011] Furthermore, the use of these material removal methods slows down the manufacturing cycle of concrete blocks, which generates a significant production cost, the latter being all the more significant as the desired tolerance values ​​are low (the machining phases are in fact longer and slower than for wider tolerance values).

[0012] The invention aims to remedy these problems by proposing a method for manufacturing a concrete masonry block calibrated to a determined height, overcoming the drawbacks of prior art methods using material removal. OBJECT OF THE INVENTION

[0013] For this purpose, and according to a first aspect, the invention proposes a method for manufacturing a masonry concrete block calibrated to a determined height, comprising the steps of filling a mold placed on a vibrating press with a mass concrete composition in the fresh state and compacting the mass concrete composition contained in the mold, the method being remarkable in that the calibration of the masonry block is obtained by filling the mold with the mass concrete composition to a height corresponding to a range between 80 and 90% of the final height of the masonry block targeted at the outlet of the oven, then pouring into the mold a second composition of concrete in the fresh state onto the compacted mass concrete composition to reach the final height of the masonry block targeted and compacting the second composition in the fresh state onto the mass composition.

[0014] Thus, by applying an additional layer of a second concrete composition to the mass concrete composition after compacting the latter, the height dimensions of the masonry block can be calibrated to the target tolerances, including low tolerances such as those of classes D3 and D4. specified above, and this without necessarily resorting to removing material from the mass concrete composition layer by machining or polishing. The application of a second concrete composition makes it possible to standardize the height of the masonry blocks and also to perfect the parallelism of their upper and lower bases. The method according to the invention thus makes it possible to manufacture masonry blocks with controlled dimensional tolerances. And unlike the conventionally implemented prior art methods which rely on the removal of material, the method according to the invention relies on the addition of material to the mass concrete.

[0015] Advantageously, holes are made on the surface of the mass concrete composition prior to pouring the second concrete composition into the mold. The formation of holes on the surface of the mass concrete layer, which mainly constitutes the block, makes it possible to improve the adhesion of the second concrete composition to the mass concrete layer.

[0016] According to a particular implementation, the holes are made during the compaction of the mass concrete composition, advantageously by means of retractable needles fitted to compaction rammers.

[0017] Advantageously, the method comprises a step of rectifying the second compacted concrete composition by machining or polishing said second composition in the fresh state or in the hardened state.

[0018] Advantageously, the second concrete composition comprises a hydraulic binder as well as mineral additions having a size less than 2 millimeters, and possibly adjuvants and / or micro-fibers.

[0019] When leaving the press, the finishing layer must adhere well to the mass concrete, which mainly constitutes the block. In addition, during the curing phase, the dimensional variations between the two materials (natural shrinkage and swelling of the concrete) must not create micro-cracks weakening the two-layer block thus produced. For these reasons, the second composition to be applied to the block will be a composition which must adhere to the mass concrete, not present any shrinkage or swelling which is contradictory to the mass concrete, and possibly be easily machinable or rectifiable.

[0020] The invention also relates to a masonry block calibrated to a determined height obtained according to the manufacturing method as described above, said block comprising two layers of concrete of different composition. Advantageously, the second concrete composition comprises a hydraulic binder as well as mineral additions having a size less than 2 millimeters, and optionally adjuvants and / or micro-fibers. DETAILED DESCRIPTION OF THE INVENTION

[0021] Other characteristics and advantages of the invention will emerge from the detailed description of the invention which follows, given by way of example.

[0022] The manufacture of a concrete masonry block conventionally comprises a step of filling a mold placed on a vibrating press with a fresh mass concrete composition followed by a step of filling the mass concrete composition contained in the mold. An operation of curing the two-layer concrete block thus formed is then carried out.

[0023] According to the invention, the method comprises an operation making it possible to obtain a concrete masonry block calibrated in height, and advantageously in flatness, between its upper and lower faces.

[0024] According to the invention, the calibration is obtained by filling the mold with the mass concrete composition to a height corresponding to a range between 80 and 90% of the final height of the intended masonry block, then by pouring into the mold a second fresh concrete composition on the freshly compacted mass concrete composition to reach the final height of the intended masonry block and by compacting the second composition on the mass composition. Provision may be made for the addition of the second composition if necessary to make up for the sub-level of composition relative to the height of the intended masonry block.

[0025] By adding a second layer of concrete to the main layer of mass concrete, the height of the masonry block can be calibrated to the target height while ensuring the flatness of the block. The masonry block thus obtained is a dimensionally calibrated two-layer block.

[0026] The concrete composition first poured into the mold (“first composition”), called “mass composition” is called “main composition” or “majority composition” while the concrete composition poured in the second stage (“second composition”) is called “additional composition”, “secondary composition” or “calibration composition”.

[0027] Advantageously, the second concrete composition comprises a hydraulic binder as well as mineral additions having a size less than 2 millimeters, and possibly adjuvants and / or micro-fibers. In order to increase the adhesion of the second composition to the first compacted concrete composition, it may advantageously be provided to make holes, impacts or the like on the surface of the mass concrete composition, prior to pouring the second concrete composition into the mold. According to a preferred embodiment, the holes are made during the compaction of the mass composition by means of retractable needles equipping the means ensuring the compaction of the mass concrete composition (rams). It is of course obvious that the holes can be made in any other way and by any other means without departing from the scope of the invention. Likewise, they can be carried out once the compacting operation of the first composition has been completed. In the latter case, the production can take place during or after drying of the composition.

[0028] Depending on the requirements, provision may be made to carry out an operation of rectification of the second compacted concrete composition by machining or polishing. The operation of rectification of the second composition may be carried out either when it is in the fresh state or when it is in the hardened state.

[0029] An example of the production of a concrete masonry block using the method according to the invention is given below.

[0030] The equipment used for producing such a masonry block comprises a mold placed on a vibrating press, distribution means for feeding the mold with fresh product to be molded and a compacting device comprising at least one compacting ram.

[0031] The dispensing means comprising a first drawer containing the mass composition and a second drawer containing the second composition. The first and second drawers move linearly between a first position where a hopper drops the fresh product into the drawer, and a second position above the mold where the product flows into the mold as the drawer advances above the mold.

[0032] The mold is then filled with the missing quantity of concrete with the second concrete composition contained in the second drawer up to the height defined by the second concrete stops. In this case, in the example described, the second stops have a thickness of 5 mm. A second compaction using the rammer is then started, until the height defined by the second stops is reached.

[0033] The masonry block then obtained is class D3 or even D4, with a smooth and regular surface.

[0034] The invention is described in the above by way of example. It is understood that a person skilled in the art is able to carry out different variant embodiments of the invention without departing from the scope of the invention.

Claims

Claims

1. A method of manufacturing a masonry concrete block calibrated to a determined height, comprising steps of filling a mold placed on a vibrating press with a fresh mass concrete composition and compacting the mass concrete composition contained in the mold, characterized in that the calibration of the masonry block is obtained: - by filling the mold with the mass concrete composition to a height corresponding to a range between 80 and 90% of the final height of the masonry block targeted at the outlet of the oven, then - by pouring into the mold a second fresh concrete composition onto the compacted mass concrete composition to reach the final height of the masonry block targeted and by compacting the second fresh composition onto the mass composition.

2. Manufacturing method according to claim 1, characterized in that holes are made on the surface of the mass concrete composition prior to pouring the second concrete composition into the mold.

3. Manufacturing method according to the preceding claim, characterized in that the holes are made during the compaction of the mass concrete composition by means of retractable needles fitted to compacting rammers.

4. Manufacturing method according to any one of claims 1 to 3, characterized in that it comprises a step of rectification of the second compacted concrete composition by machining or polishing said second composition in the fresh state or in the hardened state.

5. Manufacturing method according to any one of claims 1 to 3, characterized in that the second concrete composition comprises a hydraulic binder as well as mineral additions having a size less than 2 millimeters, and optionally adjuvants and / or micro-fibers.

6. Masonry block calibrated to a determined height obtained according to the manufacturing method according to any one of claims 1 to 5, comprising two layers of concrete of different composition.