FR2697042A1 - Low porosity cement-based covering material for roads, paved areas - contains fine sand and polymer particles to fill pores left when cement sets - Google Patents

Abstract

The material, for use e.g. in civil engineering projects, is made from a low-porosity sand with a grain size of between 0 and 4 mm, a cement with a relatively high specific surface - over 3700 cm2/g, and particles of a polymer or copolymer with a grain size of less than 15 microns, in a proportion of 5-30 per cent of that of the cement by weight, filling the pores left by the setting of the cement by virtue of their small grain size. The material has a total porous volume of less than 40 mm3/g, and a surface energy which is such that the angle formed by a droplet of water on its surface is greater than 20 degrees. USE/ADVANTAGE - For paved areas, surfaces used by vehicles or wall renderings. Increased impermeability, greater resistance to oil marks and easier removal of ice.

Description

Coating material, coating element made therefrom
material, manufacturing process
Description
The subject of the present invention is a new coating material, coating elements manufactured with this said material, new methods of manufacturing this material and a new application thereof.

 The technical sector of invention is that of building and public works.

 The main application of the invention is the manufacture of exterior floor pavers constituting public or private roads on which vehicles can circulate or park.

 Other applications are possible with the material according to the invention for producing floor or wall slabs, facade plasters and in general any type of coating which can be stained with products encrusted in the material and which are then difficult to clean, such as, in particular, the used lubricating oils from vehicles which may run on these floor coverings.

 Many materials used in coatings are known, and each can be classified according to two types of family: some according to the applications, and the qualities sought for these, such as anti-corrosion protection for metallic structures, tensile strength for thin roofing elements, waterproofing for road surfaces of civil engineering structures, etc., and others depending on the composition of these materials, which may be based on paint, rubberized material or plastic, cement with various and different additives etc ...

 The present invention is in a family of materials corresponding to a classification by composition because the application concerned is new and has never been the subject of specific research to solve the problem it poses.

 The family of material by composition in which the invention therefore falls is that of mortars or concrete containing organic fines or polymer particles.

 In this category there are various formulations according to the basic products used, their proportion, their particle size, the specific components which are added etc ... and, which after implementation undergo so-called curing and particular aftercare conservation processes.

 Each of these formulations and associated preservation methods in fact respond to a particular use then falling into the other classification by application of the qualities sought; it may be noted, moreover, that for all the coating applications that can be envisaged to date, one can practically always find a material the composition of which is as above: mortars or polymer cement concrete are used as paving material, such as sealing and / or anticorrosion coating, and / or resistant to the chemical, as a coating for a ship's deck or roadway on engineering structures, or as a material for the lining of vehicles, etc. The incorporated polymers indeed make it possible to '' increase the cohesion of hardened cement, its adhesion to the surface, improve its resistance to abrasion, chemical agents and impact, and its expansion-contraction properties, and to decrease its porosity, its risk of cracking, etc. ..

 One can cite for example among the numerous patents registered on the particular compositions in the field of polymer cements or polymer mortars, and on the corresponding desired applications and qualities, the application EP 0 069 586 published on January 12, 1983 of the Swiss Company Marley Tile GA entitled "cement mortars and concretes containing polymers and process for their manufacture" whose objective is to obtain a material whose tensile strength is high enough to make objects of small section such as roofing tiles.

 Similarly, patent application FR 2 541 672 published on August 31, 1984 by the Japanese company Nippon Kokan KK describes "a cement-polymer mortar composition" developed specifically for the protection of metal structures by adding aggregate to more than 95% glass content, special proportions between the cement, the aggregate and the polymer and the use of a butadiene-styrene polymer.

 In addition, note the patent application FR 2 653 471 published on April 26, 1991 of the Société Financière ETERNIT on "small elements of cover by replacement slate" made from hydraulic concrete loaded or not with polymer or other products which both reproduce the aesthetics of stone slate roofs and ensure good sealing; and that FR 2 614 048 published on October 21, 1988 of the Company Jean Lefebvre concerning "a waterproofing complex of road works and process etc ..." whose lower layer consists of a mortar charged with a binder bituminous based on elastomer.

 We could cite many others, but none cites or evokes the particular objective of the present invention, which is to produce a coating material which makes it possible either to prefabricate elements of the paver, tile, slab or similar type, or to make on-site plaster layers but the specific implementation is then however more difficult to control, and the main characteristic of which is to be practically unteachable and in any case detachable, in addition to good freeze / thaw resistance and impermeability which are then the consequence of the quality of intachability / detachability.

 This objective is achieved by means of a material based on cement and organic fines which comprises at least low porous sand with a particle size of between 0 and 4 millimeters, a cement with a relatively high specific surface, ie greater than 3,500 cm2 / g measured by the BLAINE method and less than 4,500 cm2 / g for known standard cements, and particles of polymer or copolymer with a particle size of less than about 15 microns and preferably 5 microns, and in proportion from 5 to 30% by weight of the cement, and preferably 15 to 25%, the particles filling and clogging the pores left by the setting reaction of the cement due to their small particle size.

 The material according to the invention has a total pore volume of less than 40 mm 3 / g, ie approximately 40% less than that of a normal dry mortar, after 28 days of storage at 80% relative humidity and at 20 ° C., and a surface energy such that the angle made by a drop of water deposited on the surface of said material is greater than 20.

 In a preferred embodiment, said material comprises gravel with a particle size of between 0 and 20 mm approximately, and likewise to reduce and ensure a low total pore volume of the material, it comprises particles of reactive fine minerals with a particle size of less than 80 approximately microns and in proportion between 0 and 50% by weight of the cement, which reactivity of said particles being requested as many times as necessary during manufacture.

 The objective of the invention is all the better achieved in this case with a process for manufacturing the material, such as at least a mixture of low porous sand, cement, particles of polymer or copolymer and of water with, in addition to reactive mineral fines, which mixture having a given consistency adapted to known means of implementation, and this said mixture is arranged according to said means of implementation.

 Indeed, if it is a question of pouring the mortar, it is necessary that it is fairly fluid thanks to an addition of adjuvant and / or water; if, on the other hand, vibrating tables or needles are used, the consistency may be thicker.

 When this initial mixture is hardened by a first series of reactions between the constituents giving a primary porosity as a function of the particle size thereof and ensuring the shaping of said material such as in molds, thanks to said means of implementation, causes, by a possible addition of water, a chemical reaction of the particles of mineral fines with the products resulting from the first series of reactions, thus creating a second network of connection between the products and reducing the primary porosity.

 When the material is dry, and this second network formed, we can add more water to cause a second series of chemical reactions creating a third network further reducing the previous porosity and so on as many times as desired to obtain a porosity given.

 A new application is thus obtained, according to the invention, of material based on cement and organic fines as it is used to produce almost intachable and detachable coating surfaces according to a given choice of components and their proportions and their particle sizes and, processing methods and treatments: the coating once produced with said material is such that a stain of used lubricating oil deposited on the surface thereof and several weeks old is completely cleaned in wiping it with a paper impregnated with a solvent.

 The result is new coating materials based on mortar or concrete containing organic fines, new manufacturing processes including new preservation processes and a new application of these said materials.

 These materials, because of their composition and associated methods of conservation, cures and post-cures, indeed meet the objective of the present invention to be intachable, detachable, resistant to freeze / thaw, waterproof, etc. thanks to the reduction of porosity and their surface energy.

Indeed, we know that the pressure with which a liquid is sucked poured on a surface of a porous material and penetrating in its pores and equal in this one to P = 2 (T x Cos e) / R
where R is the radius of the pores
e the angle made by the meniscus formed by a drop of liquid with the surface of the material and which, depending on the energy of the latter and a function both of the nature of the solid and of the liquid, is with the material of the present invention, for the same given liquid, more important than for a known material of the same family: this gives more domed drops, which in the context of the present invention form an angle e with the surface of the material, greater than 20, with water for example in the case of mortar without organic or mineral fines, e is zero is the stetal drop completely.

 T is a constant of the liquid characterizing the free surface energy or the surface tension of the latter.

 So although Cos 8, being smaller since e is larger, tends to decrease the pressure in the pores and consequently the penetration of the liquid in them, their radius being less important however increases this pressure which would then tend to do more penetrate the liquid.

However, the reduction in pore radii, depending on the composition of the material and their manufacturing process according to the invention increases
on the one hand, increases the resistance to this penetration and therefore decreases its speed, which then considerably reduces the depth of penetration for the same period of time compared with a known material of the same family, even if finally the pressure P is larger, and
- on the other hand the sieve effect which keeps the charges and the dirt on the surface, only the fluid parts in quantity then much less important being able to penetrate.

 Comparative toughness tests were carried out to verify this characteristic using a drain oil composed of hydrocarbon, metallic particles and carbon suspended in the oil.

 These solid particles have a diameter of the order of one micron and a standard cementitious material from the same family as the materials of the present invention traps them in its open pores with a diameter close to one micron. It is then very difficult, if not impossible, to remove them, while the polymer mortars according to the invention have a finer porous distribution, and this all the more with polymer mortars containing reactive mineral fines and treated according to the methods of l 'invention: solid particles of waste oil are simply deposited on the surface and are easily cleaned.

 Furthermore, the liquid is more or less absorbed by the material and in the case of unmodified mortar, the penetration height of the oil is greater than in the case of the polymer mortar according to the invention. Cleaning the oil with a hydrocarbon solvent is effective for the polymer mortar, all the more so with a polymer mortar containing mineral fines and there is no trace of the ghost of the oil, whereas for the unmodified mortar it more or less fades but reruns on the surface after a few hours.

 It is very difficult to quantify the tachability of the material, but the difference in behavior with regard to cleaning between the mortars is quite perceptible to the naked eye.

 This improved intachability and detachability, which is all the more improved in the materials and processes according to the invention for polymer mortars containing mineral fines, induces many interesting and advantageous characteristics in terms of, for example, gel and seals and clearly shows the novelty. and the interest of the invention; other benefits could be found and cited.

 The figures below give examples of results obtained in terms of pore volumes for compositions and methods according to the invention.

 Figure 1 shows two porosity distribution curves for two materials at 28 days; both are made according to the same implementation and alternating treatment of humidification and conservation, but one is carried out with a mortar of composition without addition and the other with a mortar of composition with organic fines.

 FIG. 2 represents two curves of material porosity distribution, one with the same reference mortar containing only organic fines as in FIG. 1 and the other with a mortar produced according to the same implementation and the same treatment but with in addition in its composition of mineral fines.

 FIG. 3 represents the summary of the curves of overall pore volume of the materials produced with the various mortars above and that of a reference mortar said to be normal dry and without addition and without alternating humidification and conservation, during a period of several tens days.

 The porosity variations as indicated in the attached figures were measured with a mercury porosimeter. For curves 1, 2 and 3, the materials have undergone a treatment as described above, while curve 4, known as the base cure, has been drawn for mortars considered dry, normal and without additions, kept at a constant 80% relative humidity and 20 C.

 The curves referenced 1 relate to a cement-based material but without the addition of organic or mineral fines and having undergone a cure and a post-cure according to the treatment below, this already makes it possible to obtain a better reduction of the porosity compared to the same material not having followed this treatment as can be compared in FIG. 4.

 This treatment or post-cures were carried out for the examples represented in these figures, after molding of the elements such as paving stones composed for 5 / 6th of their thickness of coarse concrete without particular sealing characteristic but essentially characteristics of solidity strong mechanics and for 1 / 6th constituting the facing or coating with a mortar corresponding to that of the present invention.

After molding said pavers, the mortars undergo an alternation of conservation at 20 "C and 80% relative humidity which can be qualified as stage 1 and, immersion in water or sprinkling which can call stage 2, with respective durations such as
from O to 2 days: step 1
2 to 3 days: step 2
3 to 7 days: step 1
7 to 8 days: step 2
8 to 28 days: step 1
28 and 29 days: step 2
29 to 43 days: step 1.

 The curves represented in FIGS. 1 and 2 represent the porous distributions of the mortars at 28 days.

 Curves 2 are curves representative of a coating material according to the invention based on cement and organic fines, the incorporation of the polymer of which has the effect of reducing, in association with the curing and post-curing treatment, the porosity and the affinity of the liquid for the solid. However, in the case of adding organic fines alone, the effect of this after-treatment is less significant and therefore not very interesting compared to that obtained with a mortar comprising in addition mineral fines as shown in curves 3 and as specified. below.

 The polymer used can be a polyvinyl acetate or a styrene butadiene or acrylic styrene, etc.

 The polymer considerably reduces the pore size and the total pore volume of the mortars such that the total pore volume of the material, as shown in FIG. 2, is less than approximately 7 mm3 / g for the pores of 1000 angstroms and above, to 20 mm3 / g approximately for those of approximately 110 angstrom, 30 mm3 / g approximately for those of approximately 70 angstrom and 40 mm3 / g approximately for 30 angstrom.

 It should be noted that the incorporation of the polymer in fact reduces the need for curing: an in-depth study on the conservation of the test pieces has indeed shown the influence of the hygrometry because it largely influences the characteristics of conventional mortars, on the other hand it is a negligible parameter for the polymer modified mortars according to the invention because the initial internal humidity remains since the reduction in pores plays not only in the characteristic intestinal ability coming from the outside, but also limits the evaporation of the trapped water therefore to inside the material there is therefore a decrease in evaporation compared to other cases and the cement setting reaction can be carried out completely without the particular need to add water. The process of the invention can therefore be carried out without real addition of water if the choice of the composition of the basic elements is optimum.

 The curve 3 in FIG. 2 represents the distribution of a total pore volume at 28 days and in FIG. 3 the total pore volume as a function of time, for a material, according to the invention, also comprising reactive mineral fines with particle size less than about 80 microns and in proportion between 0 and 50% by weight of the cement: these mineral fines can be silica fumes or finely ground slag.

 This simultaneous incorporation of mineral fines and of polymer induces a further reduction in the radius of the pores and in the total pore volume, as can be seen above in FIG. 3 because in fact it causes series of successive chain reactions, creating successive networks which clog pores whose diameter is then smaller and smaller.

 When adding mineral fines, a careful cure is necessary and the percentage of relative humidity must be high: the cure and post-cure process defined above is important in this case, because the mineral fines have a time of reaction takes longer than setting the cement and therefore need additional water to react during each successive chain reaction.

In FIG. 3, the summary of the different mortar materials used according to the invention shows by way of comparison that at 28 days we gain, compared to the reference mortar 4 sec, normal, without curing, post-curing or adding
- on curve 1, 10 points with a cure applied on the same reference mortar, 25 points with the incorporation of polymers according to the invention in the material and 35 points with the combination of polymer and slag.

 - on curve 3 the last composition makes it possible to reduce the initial pore volume by 60%, the size of the pores and the speed of absorption of water.

 The coating material according to the invention can also comprise, in its initial mixture, a concrete admixture such as a super plasticizer.

Claims (10)

 1. Coating material based on cement and organic fines, characterized in that it comprises at least low porous sand with a particle size between 0 and 4 millimeters approximately, a cement with a relatively high specific surface, ie greater than 3.700 cm 2 / g and particles of polymer or copolymer with a particle size less than about 15 microns, in proportion of 5 to 30 by weight of the cement, filling and plugging the pores left by the setting reaction of the cement thanks to their small particle size, which material having a total pore volume of less than 40 mm3 / g and a surface energy such that the angle made by a drop of water deposited on the surface of said material is greater than 20.  2. Coating material according to claim 1 characterized in that it also comprises gravel with a particle size between 0 and 20 millimeters approximately.  3. Coating material according to any one of claims i and 2 characterized in that it also comprises particles of reactive mineral fines with a particle size less than about 80 microns and in proportion between 0 and 50% by weight of the cement, which reactivity of said particles having been requested as many times as necessary.  4. Coating material according to claim 3 characterized in that the mineral fines are silica fumes or finely ground slag.  5. Coating material according to any one of claims 1 to 4 characterized in that it comprises a concrete admixture such as a superplasticizer.  6. Coating material according to any one of claims i to 5 characterized in that its total pore volume is less than approximately 7 mm3 / g for the pores of 1000 angstroem and above, approximately 20 mm3 / g for those of 110 angstroem approximately, 30 mm3 / g approximately for those of 70 angstroem approximately and 40 mm3 / g approximately for 30 angstroem approximately.  7. Coating element characterized in that the layer of material constituting its outer surface is produced according to any one of claims 1 to 6 and its said surface is such that a stain of used lubricating oil deposited thereon and several weeks old is completely cleaned by wiping with a paper impregnated with a solvent.  8. A method of manufacturing a material based on cement and organic fines, characterized in that  - A mixture is produced at least of low porous sand, cement, particles of polymer or copolymer of water, and reactive fine minerals, which mixture having a given consistency adapted to known means of implementation;  - We have said mixture according to said means of implementation;  - When this initial mixture is hardened by a first series of reactions between the constituents giving a primary porosity as a function of the particle size thereof and ensuring the shaping of said material, as a function of said means of implementation, a reaction is caused chemical particles of mineral fines with the products from the first series of reactions, creating a second bonding network between the products and reducing the primary porosity.  9. Manufacturing process according to claim 8, characterized in that components of particle size are used such that for the sand it is between 0 and 4 mm approximately, for the polymer or copolymer particles constituting the organic fines lower at about 15 microns and in proportion from 5 to 30% by weight of the cement, and for mineral fines less than about 80 microns and in proportion from 0 to 50% by weight of the cement, the latter being of relatively high specific surface greater at 3,500 cm2 / g.  10. Application of a material based on cement and organic fines, characterized in that it is used to produce almost intachable and detachable coating surfaces, so that the coating once produced with said material is such that a stain of used lubricating oil deposited on the surface of it and several weeks old is completely cleaned by wiping it with a paper impregnated with a solvent.