FR2970963B1

FR2970963B1 - ANTI-TERMITE CONCRETE OR MORTAR AND METHOD OF MANUFACTURING THE SAME

Info

Publication number: FR2970963B1
Application number: FR1150810A
Authority: FR
Inventors: David Chopin
Original assignee: FINANCIERE VM BETON
Current assignee: EDYCEM, FR
Priority date: 2011-02-02
Filing date: 2011-02-02
Publication date: 2019-06-07
Anticipated expiration: 2031-02-02
Also published as: FR2970963A1

Abstract

Béton ou mortier à base d'une matrice de liant hydraulique comprenant du ciment (C) et/ou de la chaux, et des granulats choisis parmi des sables (S) et/ou des graviers (G) de dimension supérieure ou égale à 0,5 mm environ, caractérisé en ce que ladite matrice renferme un agent biocide, notamment vis-à-vis des insectes sur un support minéral poreux, de préférence sous forme de granulés (A), de granulométrie comprise entre 0,5 mm et 10 mm environ, de préférence 0,5 mm à 6 mm, enrobés dans ladite matrice et de résistance mécanique inférieure à celles des granulats, de manière à constituer, lors de la fissuration du mortier ou du béton, des points de passage des fissures (F), mettant ainsi à nu ou scindant le granulé support de l'agent biocide. Utilisation en tant que béton de structure, de blocs de soubassement, ou de mortier pour enduits de soubassements.Concrete or mortar based on a matrix of hydraulic binder comprising cement (C) and / or lime, and aggregates chosen from sand (S) and / or gravel (G) of dimension greater than or equal to 0 , Approximately 5 mm, characterized in that said matrix contains a biocidal agent, especially with regard to insects on a porous mineral support, preferably in the form of granules (A), with a particle size of between 0.5 mm and 10 mm. mm, preferably 0.5 mm to 6 mm, embedded in said matrix and of lower mechanical strength than those of the aggregates, so as to constitute, during the cracking of the mortar or the concrete, cracks (F ), thereby exposing or cleaving the carrier granule of the biocidal agent. Use as structural concrete, sub-base blocks, or mortar for base coats.

Description

The present invention relates to a concrete or mortar with biocidal properties, especially insecticide, and more particularly anti-termite and its manufacturing process. To date, to fight against the invasion of insects, and more particularly termites, in homes and buildings, physical barriers or chemical barriers are used. Physical barriers include concrete walls or screeds, fine wire meshes, and sand piles of particular grain size that create a bulwark against insect access. These barriers can, however, be subject, over time, to degradations, such as cracks, creating passages within these materials. Some methods of termite protection consist in then introducing into these cracks an anti-termite agent. This "filling" implements large quantities of biocide, which is not without causing problems to the inhabitants and to the environment, especially in case of water entrainment. rain.

Chemical barriers, for their part, consist in spreading in or around the trenches, before the pouring of the foundation concretes or the construction of walls, or spraying on the already existing walls, the insecticide in the form of a solution or of a suspension. Again the environmental risks are not negligible, the insecticide can be easily leached by rainwater, or the proximity of an underground water table, and quickly no longer play its repellent or toxic role vis-à-vis insects referred . There are also barriers made of a film impregnated with biocidal product spread on the bottom and the walls of the trenches before concrete pouring: their implementation is restrictive and delicate, any tear or perforation may ruin its barrier effect. Such films buried in the soil can also be degraded over time and lose their repellent or toxic action vis-à-vis insects after a few months or years.

More recently it has been envisaged to introduce the biocidal agent directly into the mortar or concrete during the preparation of the cementitious matrix, or into polymers impregnated with the said agent in the form of fibers or particles, mixed with the said cement matrix. . Large concentrations are necessary to obtain sufficient efficiency, which can cause reductions in the mechanical performance of the mortar or concrete, or even completely block the hydration reaction of the cement.

The presence of this polymer mixture in the cementitious matrix also poses difficulties at the end of life of these concretes or mortars, the polymers not being considered as DIB (Industrial Waste Banal) and therefore can not be treated in the same circuits recycling or landfilling as mineral materials.

A first object of the invention is to overcome the above drawbacks by proposing a concrete composition or anti-termite mortar retaining its effectiveness vis-à-vis insects in case of cracks.

Another object of the invention is to provide a composition of mortar or concrete with a reduced concentration of biocidal molecule. For this purpose, the present invention relates to a concrete or mortar based on a matrix of hydraulic binder comprising cement and / or lime, and aggregates selected from sands and / or gravel of size greater than or equal to 0 , Approximately 5 mm, characterized in that said matrix contains a biocidal agent, in particular with respect to insects on a porous mineral support, preferably in the form of granules, with a particle size of between approximately 0.5 mm and 10 mm ( preferably 0.5 mm to 6 mm) embedded in said matrix and of lower mechanical strength than those of the aggregates, so as to constitute, during the cracking of the mortar or concrete, cracks crossing points, thereby exposing or cleaving the carrier granule of the biocidal agent.

The carrier granules of the biocidal agent are of the same order of magnitude as the sand, but of particle size corresponding to at least 10 times the particle size of the cement particles, that is to say preferably of dimensions of between 2 mm and About 6 mm for a concrete, and preferably of dimensions between about 0.5 mm and 2 mm for a mortar.

Biocide means in this document any substance which, in accordance with Article 2 of the European Directive 98/8 EC, is "intended to destroy, repel or render harmless harmful organisms, prevent the action or to fight them in any other way, by a chemical or biological action ". Under this definition, pest control products are considered, in particular those used to control arthropods, such as arachnids and insects. Undesirable insects include xylophagous insects, and more particularly termites, which are one of the most destructive xylophagous insects in relation to dwellings, especially wood or derived elements used in constructions.

Thus the concrete or mortar according to the present invention is initially a physical barrier, then in a second time, in case of cracks, a chemical barrier against insects such as termites; in fact, porous granules, more friable than sand or gravel, appear at the edge of cracks or split by releasing the biocidal molecule. Depending on its nature, this biocidal molecule can then be desorbed from the mineral support exposed, by sublimating itself in air or spreading in the water possibly present in the crack by capillarity, and thus constitutes an active repellent or insecticide.

The biocide molecule being incorporated, via the mineral support impregnated with said molecule, within the hydraulic binder, and embedded in the latter, it is protected from environmental damage (rain, sun), until it is desorbed during the occurrence of a crack where it can act locally and effectively. As this molecule is present exclusively on the granules or grains of said inorganic support, the quantity used is much less than in the concretes or mortars of the prior art. Preferably said granules contain a mass percentage of biocidal agent, relative to the inorganic support, of between 0.001 and 2%, preferably between 0.05 and 1%.

Preferably, said mineral support is based on limestone, expanded clay, expanded shale, pozzolana, calcium silicate, or pumice.

The granules forming this porous mineral support advantageously have a porosity of between 10 and 80% by volume, preferably between 20% and 60% by volume, and a fragmentation aptitude, measured according to the EN 12620 standard (value under test). Los Angeles), advantageously between 35 and 40, the standard aggregates for concretes and mortars generally having a value of between 10 and 30. The biocidal agent may be a repellent and / or insecticidal agent, preferably an anti-termite agent. selected from the group consisting of pyrethroids, preferably bifentrine, deltamethrin, or permethrin, of the benzoylurea family, preferably flufenoxoron, hexaflumuron or diflubenzuron, or of the phenylpyrazole family, preferably fipronil, or a mixture thereof.

These molecules can be on the support in the pure state or diluted in a suitable solvent also fixing by absorption or adsorption in the pores of the inorganic support.

In order to limit the diffusion of the biocidal agent into the mixing water of the concrete of the mortar during mixing, the granule is advantageously coated with a coating film, preferably impervious to water, of fat-soluble type.

The distribution of this mineral support within the concrete or mortar is carried out in the most homogeneous manner possible in order to allow, when the occurrence of stress causing cracks, to direct said cracks in the vicinity and through this mineral support more friable than other aggregates.

Preferably, the concrete or the mortar according to the present invention contains from 0.1 to 5% by weight, preferably from 0.5 to 2% by weight, of biocidal carrier granules relative to the total mass of concrete or fresh mortar including the mixing water, the concrete containing biocidal carrier granules of dimensions preferably between 2 mm and 6 mm and the mortar of the biocidal carrier granules preferably of dimensions between 0.5 mm and 2 mm. mm.

The mineral support has the advantage over an organic support to be on the one hand sufficiently rigid to support the mixing of the concrete during its preparation and on the other hand sufficiently brittle to split when the appearance of cracks. Organic supports are not suitable because they can either disintegrate when mixing and mixing concrete or mortar in the presence of aggregates such as sand or gravel, or, in the case of synthetic polymers, to be crack-resistant by being more flexible than the mineral support.

Mortar or concrete, according to the present invention, finds an interesting application in the field of building as a mortar or concrete termite. For example, when the biocidal molecule incorporated in the mineral carrier is permethrin.

The present invention also relates to a process for the preparation of a fresh mortar or concrete, as described above (ready-to-use), comprising the following steps: the preparation of granules supporting a biocidal agent by fixing the biocidal agent on the porous mineral support, in the form of granules, of lower mechanical strength than the aggregates of the mortar or concrete, optionally comprising an external protective film of the granulate with respect to the mixing water and the other constituents concrete or mortar, introduction into the mixer of the constituents of the mortar or concrete, as well as granules carrier of biocidal agent, preferably before the beginning of the mixing, - addition of the mixing water of the mortar or concrete and the adjuvants then kneading the assembly, preferably for a limited time, between 1 and about 10 minutes, not to degrade said granules.

A mixing time of 4 to 6 minutes is preferred. Indeed, before taking the cementitious composition, one must avoid the diffusion of the biocide molecule in the mixing water and limit its physical degradation by aggregates such as sand and gravel.

The mortar or concrete thus prepared can be used as foundation concrete, slabs, base blocks, planelles or as facade or underlay mortar.

Indeed, termites being living insects protected from light and penetrating into buildings and dwellings by the ground, the anti-termite granules according to an advantageous embodiment of the present invention can be introduced into structural concretes. , base block concretes and mortars for base coatings with the general compositions as presented in Table 1 below.

Table 1 (Percentages are expressed in% by mass of the total mass of concrete or mortar)

Other features and advantages of the present invention are presented in the examples hereinafter cited without any limitation and with reference to the figures in which

Figure 1 shows schematically a concrete according to the present invention during the appearance of cracks;

Figure 2 is a schematic of the experimental device for testing the effectiveness of a concrete according to the present invention.

Examples

Examples 1 to 7 below describe various attempts to introduce an insecticidal agent, here an anti-termite agent, onto a granular support in a concrete whose composition is as follows:

-11.3% CEM II cement 42.5 R -36.4% sand 0/4 mm -10.3% chippings 6/10 mm -6.7% water

The various granules of any shape and size of 1 to 4 mm tested, are impregnated in the heart of a 10% permethrin solution in a plant dispersant such as a castor oil. Permethrin is here a 25/75 cis / trans racemic mixture.

The dry constituents of the concrete (cement, sand, chippings) are introduced into a ready-mix concrete batch mixer and the anti-termite granules in an amount of 1.25% by weight before the mixing water. Then the whole is kneaded 55 seconds.

Example 1 (comparative): natural organic support

The pellets consisting of 99% apples, 1 to 4 mm diced maize and 1% permethrin solution were introduced into the concrete composition described above. There is a lack of connection between the cement matrix and the anti-termite granules.

Example 2 (comparative): natural organic support

The granules consist of cereals extruded at 98% by weight with 1% permethrin solution and 1% yellow dye. The result is identical to Example 1. There is no bond between the granules and the cement matrix.

Example 3 (comparative): mineral support

The granules consist of 99% diatomaceous earth and 1% permethrin solution. This mineral support is too absorbent and leads to an absorption which is not uniform within all the granules.

Example 4 (comparative): mineral support

The granules consist of 99% kieselguhr (fossilized microorganisms) and 1% permethrin solution. It is noted that this material is too friable and leads to embrittlement of the concrete.

Example 5

The granules consist of 99% yellowish-white tufa stone (Turonian calcium silicate) with 1% permethrin solution. The density of this material is 0.85, its porosity (by volume) is 40 to 50% and it has a fragmentation ability, measured according to EN 12620 (Los Angeles test) from 35 to 40.

The tests carried out show that the granules are well coated and are not degraded during mixing. They are also clearly visible in the cement matrix after the setting of the concrete, which makes it possible to visually check their presence.

EXAMPLE 6 Example 5 is reproduced with granules of the same composition as those of Example 5 in the presence of a fat-soluble, water-insoluble coating agent which creates a protective film that is not very soluble in mixing water.

Good results consistent with those of Example 5 were observed.

These granules remain visible in the concrete: of clear color they are distinguished from the cement and other aggregates generally of gray color. They do not modify the physical properties of the concrete or the mortar, with the introduced proportions.

Indeed, in a comparison with a TJ MPa strength control concrete at 28 days, the same mechanical resistance is found on the concrete containing the antitermite granules.

In splitting failure tests carried out on cylindrical concrete specimens 110 × 220 mm, it appeared, as shown schematically in FIG. 1, that the cracks F preferably pass through the termite granules A of lesser mechanical strength than the aggregates (sand S or gravel G) with Los Angeles values between 10 (diorite) and 30 (hard limestone), granules (A) and aggregates being embedded in the C cement matrix.

Example 7: efficacy test of termite concrete

An equivalent concrete mortar (MBE according to the recommendations of the CALIBE National Project) of mass composition:

-21.2% of CEM II cements 42.5 R -64.6% sand 0/4 mm -12.9% water and comprising a content of termite granules according to Examples 5 or 6 of 1, 25% and containing 1% by mass of permethrin were tested for efficacy according to the following standards: • XP X 41-542: Accelerated aging test of treated materials before biological tests - Percolation test • XP X 41-550 : Determination of the anti-termite efficacy of products and materials for use as a barrier to soil and / or walls

To do this, a colony of 800 termites workers of the family Rhinothermitidae were used. The tests were carried out on eight specimens of concrete including 4 treated and 4 untreated (control devices).

Percolation test: All 8 specimens underwent a percolation accelerated aging test according to the XP X 41-542 standard before being subjected to termite contact according to the XP X 41-550 standard for 4 weeks.

The manufacture of the test pieces of mortar was carried out after hydration of the cylindrical matrix of cylindrical shape of diameter 54 mm, in which were perforated four identical cylindrical holes parallel to the axis of the cylinder, 3 mm in diameter, distributed over a circumference 30 mm in diameter. Determination of anti-termite efficacy:

These concrete specimens were placed in a cylinder schematized in FIG. 2. This cylindrical tube 3 made of glass having an inside diameter of 50 mm and a height of 150 mm closed at its two ends with a foam cover 1 and resting on a support 10 of petri dish type. It is positioned vertically and is divided into three compartments, an upper compartment containing a piece of wood 2 termite culture support resting on the upper part of a cellular foam 4 in which were drilled two holes of diameter approximately 3 mm crossing the foam up and down. The intermediate portion consists of the specimen 6 of concrete comprising four axial perforations 11, the lower compartment of the cylinder 3 is filled with Fontainebleau sand 8 covering a piece of wood forming bait 9 constituted by sapwood maritime pine. The three compartments of this cylinder are secured to each other by a transparent adhesive tape 5, for quick assembly and disassembly.

The tests were carried out in four copies. The four test tubes were first subjected to a percolation test. This consisted of passing four liters of distilled water through the holes 11 drilled in concrete 6 at the rate of 40 drops per minute. At the end of this percolation test, the test pieces are dried for two weeks.

The principle of the efficiency test is to evaluate the treated concrete by positioning it between two compartments, one of which contains termites, and the second, empty of termites containing a wet sand and a piece of bait wood. About 200 termites made up of workers are positioned at the top of each device at the beginning of the tests. The effectiveness of the treated concrete was evaluated after 4 weeks from: • The penetration depth of termites in the sand, • The rating of the damage on the wood bait (from 0 to 4, 0 = no attack at 4 = maximum damage) • The number of termites surviving in each mount.

The results are shown in Table 2 below.

Table 2

These results show that the untreated concrete is subjected to a significant attack of termites. On the contrary, at the end of the test period, no living termite was found in the lower part (sand) in the four devices with the anti-termite treated concrete. This concrete is therefore an effective anti-termite barrier, while containing a reduced amount of anti-termite agent, compared with chemical antitermite barriers of the prior art.

Claims

1. Concrete or mortar based on a matrix of hydraulic binder comprising cement (C) and / or lime, and aggregates chosen from sand (S) and / or gravel (G) of greater or equal size at about 0.5 mm, characterized in that said matrix contains a biocidal agent, in particular with respect to insects, on a porous mineral support, preferably in the form of granules (A), with a particle size of between 0.5 mm and 10 mm, preferably 0.5 mm to 6 mm and of lower mechanical strength than those of the aggregates, said granules containing a mass percentage of biocidal agent of between 0.001 and 1% and being embedded in said matrix, the porous mineral support constituting, during the cracking of the mortar or the concrete, cracks (F), thereby exposing or separating the carrier granules of the biocidal agent.

2. Concrete or mortar according to claim 1, characterized in that said mineral support is based on limestone, expanded clay, expanded shale, pozzolana, calcium silicate, or pumice.

3. Concrete or mortar according to claim 1 or 2, characterized in that the granules (A) forming the porous mineral support have a porosity of between 10 and 80% by volume, preferably between 20% and 60% by volume, and fragmentation ability, measured according to EN 12628 (test value in Los Angeles), between 35 and 40.

4. Concrete or mortar according to any one of the preceding claims, characterized in that the granules contain a mass percentage of biocidal agent, relative to the inorganic support, between 0.05 and 1%.

5. Concrete or mortar according to any one of the preceding claims, characterized in that the biocidal agent is a repellent and / or insecticidal agent, preferably an anti-termite agent chosen from the pyrethroid family of molecules, preferably bifentrine, deltamethrin, or permethrin, of the benzoylurea family, preferably flufenoxoron, hexaflumuron or diflubenzuron, or of the phenylpyrazole family, preferably fipronil, or a mixture thereof.

6. Concrete or mortar according to any one of the preceding claims, characterized in that the granule is coated with a liposoluble coating film, non-water-soluble, to limit the diffusion of the biocidal agent in the water mixing concrete or mortar.

7. Concrete or mortar according to any one of the preceding claims, characterized in that it contains from 0.1 to 5% by weight, preferably from 0.5 to 2% by weight, granules (A) agent carrier biocide relative to the total mass of concrete or fresh mortar including mixing water.

8. Concrete according to any one of the preceding claims, characterized in that it contains granules (A) biocide agent carrier with dimensions of between 2 mm and 6 mm.

9. Mortar according to any one of the preceding claims, characterized in that it contains granules (A) biocide agent carrier of dimension between 0.5 mm and 2 mm.

10. A method of preparing a mortar or concrete according to any one of the preceding claims comprising the steps of: - the preparation of biocidal agent carrier granules by fixing the biocidal agent on the porous mineral support, in the form of granules of lower mechanical strength than the aggregates of the mortar or concrete, optionally comprising a protective film of the granulate with respect to the mixing water and the other constituents of the concrete or the mortar, said film being liposoluble, non-water-soluble - introduction into the mixer of the constituents of the mortar or concrete, as well as granules carrier biocide agent, preferably before the beginning of mixing, - adding the mixing water of the mortar or concrete and admixtures then mixing of the together, preferably for a limited time, between 1 and about 10 minutes, not to degrade said granules.