FR2578778A1 - Process for making a micro-mortar, micro-mortar obtained by this process and conditioning of the components of the micro-mortar - Google Patents

Abstract

With siliceous sand are mixed: a hydraulic binder, such as cement or the like; the water necessary for hydrating the binder; and inorganic fibres, in particular glass fibres. Before introducing the hydraulic binder, an epoxy composition in aqueous medium is separately prepared, the inorganic fibres 2 intended to reinforce the micro-mortar being incorporated into this epoxy composition; a premixing of the sand and of the epoxy composition, containing the inorganic fibres 2, is carried out; and only then is the hydraulic binder and its hydration water added to the mixture thus prepared. Components of the micro-mortar can be conditioned in a bucket.

Description

METHOD FOR MAKING A MICROMORTIER, MLCROMORTIER OBTAINED
BY THIS PROCESS AND PACKAGING OF MICROMORTIAL COMPONENTS.

The invention relates to a method for making a micro mortar reinforced with mineral fibers, in particular glass fibers, method according to which one mixes with sili sand.
those: a hydraulic binder, such as cement or the like, the water necessary for the hydration of the binder; and mineral fibers.

 By the term "micro mortar" is meant a mortar in which the sand used consists of grains whose average diameter is less than 1 mm and, preferably, less than 0.5 mm.

 A micro mortar of this type is intended, for example, for the production of facade cladding plates, or facade elements of storey height or more of large area; such a mortar can also be used for cladding of industrial buildings, curtain walls, bands, cornices, parapets, sculptures, street furniture. The micro mortar can also be used for lost formwork forming the outer skin of works such as posts, beams, lintels, wall walls, collectors.

 It is known that the purpose of introducing mineral fibers, in particular glass, into the mortar is to increase the mechanical strength of this mortar. However, the results obtained to date have not fully met expectations. One of the aims of the invention is to provide a process for making a micrortort, containing mineral fibers, which makes it possible to obtain a significant increase in the mechanical strength of this mortar.

 Another object of the invention is to provide a method, the implementation of which is simple, rapid and effective.

 According to the invention, a process for making a cromortier reinforced with mineral fibers, in particular glass, of the kind defined above, is characterized by the fact that before introducing the hydraulic binder - a composition is prepared, separately epoxy in an aqueous medium, the fibers intended for reinforcing the micro mortar being incorporated into this epoxy composition - a pre-mixing of the sand and of the epoxy composition containing the fibers is carried out - and then, only, the binder is added to the mixture thus prepared hydraulic and its hydration water.

 By operating in this way, the epoxy composition, the pH of which is weakly basic, of the order of 8 or 9, covers the mineral fibers and protects them against the alkaleaction which could be generated by the strongly basic pH, for example of the order of 13 to 14, which appears when the hydraulic binder and its water of hydration are introduced into the mixture.

 Preferably, the fibers immersed in the epoxy composition are cut to an average length of 25 mm to 30 mm.

 In the case of glass fibers, the amount added can be of the order of 20 kg to 50 kg of fibers per m3 of finished mortar paste.

 Generally, the epoxy composition comprises two components, namely an epoxy resin and a hardener intended to be poured into the resin at the time of use; advantageously, the glass fibers have been previously introduced into one of the components formed by the epoxy resin.

 A nonionic surfactant can be added to the epoxy composition, in particular at a rate of 0.5 kg to 1 kg per m 3 of finished mortar.

 An example of an aqueous epoxy composition which can be used is that known under the commercial name of "Hydrepoxy 260".

Preferably, before adding the epoxy composition to the sand, a synthetic adjuvant, in particular that known under the commercial name of "Meltherm", or an adjuvant conforming to that described and claimed in the patent, is mixed with this sand.
FR 2,364,870 filed on September 21, 1976.

 This synthetic adjuvant can be introduced at a rate of approximately 15 kg of adjuvant per 1000 kg of sand.

 Synthetic adjuvant is added to dry or semi-moist sand, i.e. no water is added during the dispersion of the synthetic adjuvant in sand which can be carried out using a mixer with vertical or horizontal shaft, or using a concrete mixer with tilting drum.

 Before even adding the synthetic adjuvant, a metal oxide can be dispersed, dry, in the sand, in particular at a rate of 1 kg per 1000 kg of sand, for the purpose of chlorinating the micro mortar.

 The invention also relates to a micro mortar prepared according to the process defined above.

 The invention also relates to a package for components of such a micro mortar, this package being characterized in that it comprises a bucket, or the like, in the bottom of which is the resin of the epoxy composition, resin in which are plunged the glass fibers into a bucket, mounted at the top of the bucket so as to close it, the bottom of this bucket containing the hardener intended to be poured into the resin, this hardener being isolated from the volume located above the bucket by a waterproof film or the like, while the synthetic adjuvant and / or any coloring powder are placed in respective sachets placed in the upper volume of the bucket, the latter as well as the bucket being closed by a lid.

 The invention consists, apart from the arrangements set out above, of a certain number of other arrangements which will be more explicitly discussed below in connection with a particular embodiment described in detail with reference to the accompanying drawings, but which is in no way limiting.

 FIG. 1, of these drawings, is a diagram illustrating the improvement in mechanical strength of the micro mortier of the invention.

 FIG. 2, finally, is a diagram illustrating a packaging for the components of a micro mortier according to the invention.

 To prepare a micrortort, according to the invention, the procedure is as follows.

 Having siliceous sand, for example of the "Fonta nebleaul" type, the average grain diameter of which is less than 1 min, and preferably less than 0.5 mm (range 0 / 0.5 sm), this sand is dispersed , coloring powder consisting of a metal oxide.

 The sand used is dry or semi-wet sand, that is to say that no water is added to the sand for the dispersion and mixing phase.

 This first phase of mixing and dispersion can be carried out in a mixer with vertical or horizontal shaft, or in a concrete mixer with tilting drum. The tank of the mixer or of the concrete mixer used must be watertight because it will later be used to receive a liquid.

 The sand is introduced first into the tank of the mixer or the concrete mixer.

 the coloring powder (metal oxide) is then dispersed.

Generally, such a metal oxide has a surface
Blaine of the order of 35,000 to 45,000 cm2 / g. After stirring for approximately 15 to 20 seconds of the sand and of the metal oxide added, it is found that the color of the sand is homogeneous, which indicates a satisfactory dispersion of the metal oxide.

 It has been found, surprisingly, that such a homogeneous coloration can be obtained with only 1 kg of metal oxide for approximately 1000 kg of sand, owing to the fact that we moderate dry.

After the metal oxide has dispersed, a synthetic adjuvant, in particular that known under the trade name of "is added to the mixture, still" dry "(or semi-wet), in the tank of the mixer or the concrete mixer. Meltherm ", or an adjuvant confirms that described and claimed in the patent
FR 2 3-4 870 filed on September 21, 1976.

 The amount of synthetic adjuvant added is about ~ 5 kg per 1000 kg of sand.

 The admixture mixture is obtained by stirring for a time of the order of 15 to 20 seconds which makes it possible to obtain perfect dispersion of the adjuvant.

An adjuvant such as Melthe- has a surface
Blaine of approximately 9,000 cm2 / g.

 After this stirring time of 15 to 20 seconds, it is found that the adjuvant has coated the grains of sand in a substantially homogeneous manner.

 It should be noted that "Meltherm" is hydrophobic due to the stearates it contains. Its introduction in the dry or slightly wet phase, before the introduction of the hydraulic binder (cement) and the water of hydration is therefore advantageous.

 The operations described above constitute a first phase in the example described for the preparation of the mortar.

 During a second phase, an epoxy composition is prepared separately in an aqueous medium, glass fibers being incorporated into this epoxy composition.

 The preparation of the epoxy composition is carried out independently of the mixer or the concrete mixer. Generally, the epoxy composition comprises a hardener intended to be poured, when the composition is used, in an epoxy resin.

 The glass fibers, intended for the reinforcement of the micro mortar, were previously immersed in the epoxy resin.

 The linear mass of the glass fibers used can be of the order of 2,400 tex. These fibers are cut to an average length of 25 mm to 30 mm to be immersed in the epoxy resin. The amount of glass fiber added is to lose it from 20 kg to 50 kg per m3 of finished mortar paste.

 The quantity of epoxy resin is of the order of 25 to 50 kg per m3 of finished mortar paste, and the quantity of hardener is also of the order of 25 to 50 kg per m3 of finished mortar paste.

 A nonionic surfactant is advantageously added to the epoxy resin, in particular at a rate of 0.5 kg to 1 kg per m 3 of finished mortar paste. An example of such a product is known under the trade name "Galcran".

 To prepare the epoxy composition, the resin, in which the glass fibers are immersed, is placed in a container such as a bucket or the like. The hardener is poured into the resin and then stirred.

 Then added to this mixture the water necessary to mix the epoxy composition.

 The epoxy resin whose pH is weakly basic (of the order of 8 to 9) coats the glass fibers, the epoxy resin being a binder and not an adjuvant.

 As will be explained below, the conditioning of the epoxy composition can be provided for a determined volume of finished mortar paste in place, for example per 1000 liters of mortar in place.

 An example of an epoxy composition, in an aqueous medium, capable of being used for the process of the invention, is formed by the epoxy composition known under the trade name of "Hydrepoxy 260" sold by the Compagnie Française de Produits Industriels.

 When this second phase is completed, the ready-to-use epoxy composition is therefore available.

 We then approach the third phase of the process.

 This third phase consists in carrying out a premixing in the mixer or the concrete mixer used during the first phase, of the epoxy composition, in aqueous medium, prepared during the second phase, with the mixture of sand, of admixture synthesis and coloring powder carried out during the first phase. Because the tank of the mixer or the concrete mixer used is waterproof, as indicated above, the introduction of the epoxy composition into an aqueous medium and the mixing of this composition and of the mixture of sand, adjuvant and coloring powder without loss of product.

 This mixing, obtained for example by the rotation of the mixer or the concrete mixer, takes place for about 30 seconds.

 When this pre-mixing has been carried out, we pass to the fourth and last phase of the preparation example described.

 This fourth phase consists in carrying out the final mixing by introducing, into the mixer or the concrete mixer, the hydraulic binder and the water necessary for the hydration of this binder.

 This hydraulic binder generally consists of cement; lime can be incorporated into the cement, for example when the micro mortar is intended to be sprayed vertically as a plaster.

 The quantity of hydraulic binder used is of the order of 700 kg per m3 of finished mortar paste.

 It is also possible to introduce, during this final mixing, metallic fibers, for example stainless steel fibers, in particular when the micro mortar is intended for the subsequent manufacture of cladding. These metal fibers are cut to lengths of the order of 25 mm to 30 mm and the quantity of metal fibers introduced can vary, for example, from 25 kg to 40 kg per m3 of finished mortar paste.

 The mixing and kneading ensure perfect dispersion of the metallic fibers in the dough; glass fibers surround the metal fibers.

 During this second phase, it is possible, in a first step of the order of - 30 seconds for example, to carry out the mixing of the hydraulic binder and of the water which have just been introduced then, in a second step, introduction of the metal fibers, carry out another stirring for about 30 seconds also intended for dispersing the metal fibers within the dough.

 When it is desired to expand the mortar during setting, in particular in the case of cladding, it is advantageous to accelerate the speed of rotation of the mixer or the concrete mixer during this fourth phase. The speed of rotation can be increased, for example, to 120 tcrs / minute, while in the previous phases, the speed of rotation was lower than this value.

 As an indication, to give an idea of the expansion of the product, the density of the dough, at the start, is approximately 2 kg / liter, after descending, after stirring, to a stabilized value of approximately 1 , 8 kg / liter.

 It should be noted that the introduction of Meltherm during the first phase makes it possible to ensure expansion of the dough, by entrainment of air. This adjuvant also ensures: homogenization, by anti-segregation effect of the components excellent plasticity; accelerated hardening; a good seal, due to the stearates used in the composition of the synthetic adjuvant.

When the hydraulic binder, especially cement, is introduced into the mixture, the pH becomes strongly basic, reaching 13 or 14. Because the glass fibers are sensitive to the alkali-reaction, they could be altered by such a strong basicity; however, the presence of the epoxy composition in an aqueous medium and the action of "Meltherm" bring the pH down to a value at most equal to 12 after 7 days. Glass fibers are little affected
FIG. 1 illustrates the increase in the mechanical resistance of the micro mortar, reinforced with glass fibers, obtained by a process according to the invention.

 These curves represent the variation in the flexural strength of test pieces obtained from the mortar, as a function of the time plotted on the abscissa and expressed in days. The time scale, on the abscissa, is proportional to the square root {\ r). The flexural strength, plotted on the ordinate, is expressed in MPa.

 Curve E corresponds to the flexural strengths of test pieces obtained using a microtortier prepared according to the example described above, into which were introduced, on the one hand, the synthetic adjuvant constituted by "Meltherm" and, on the other hand, the epoxy composition in an aqueous medium. As an indication, for one m 3 of finished mortar paste, the quantity of t'Melt.hermt 'is of the order of 15 kg, the quantity of epoxy composition (resin + hardener) is of the order of 80 kg, while that the quantity of fibers is of the order of 40 kg.

Curve D corresponds to the flexural strength of test pieces obtained from a micro mortar prepared with the addition of the "Meltherm" synthetic adjuvant alone, without the introduction of an epoxy composition. For the two curves E and D, the
3 same quantities of glass fibers (of the order of 40 kg per m of finished mortar paste) were introduced into the mortar.

In the case of curve D, the quantity of "Meltherm" is of the order of 70 kg per m3 of finished paste, without epoxy composition.

 We see that the curve E is located above the curve D, as well for times of two days, seven days and beyond up to 365 days (ie a year). The biggest difference in favor of curve E is at two days then at 28 days and beyond. Curve D approximates curve E for the tests carried out seven days after the preparation of the mortar.

 Curve E1, located below curve E corresponds to a mortar assay according to which the amounts of glass fibers and of epoxy composition are less than those used for curve E, the amount of "Meltherm" being the same as for curve E. For curve El, for 1 m 3 of finished mortar paste, about 30 kg of glass fibers and 70 kg of epoxy composition were added.

 Curve E2, located below curve El, corresponds to an even lower dosage of glass fibers (approximately 20 kg per m3 of mortar paste) and of epoxy composition (approximately 50 kg per m3 of finished paste); the quantity of "Meltherm" is also slightly reduced (around 12 kg per m3 of dough).

 Curve E3 corresponds to a dosage of approximately 30 kg of "Meltinerm" and 100 kg of epoxy composition, and without glass fibers. It immediately appears that the flexural strengths, illustrated by this curve E3, are considerably reduced in the absence of glass fibers.

 Curves E, E1 and E2 show that the flexural strength of the glass fiber reinforced mortar does not decrease as the mortar ages. This good result can be attributed to the absence of degradation of the glass fibers reinforcing the mortar.

 The epoxy composition in an aqueous medium, in addition to its protective effect on glass fibers in the alkaline medium due to cement, and its effect of improving the mechanical resistance of the products obtained, ensures a reduction (jointly with "Meltherm") of the risk of microcracks. The epoxy composition also acts as a binder and as a reinforcement of the cement, increases the adhesion of the paste to the reinforcements and to the support in the case of projection of the mortar paste on walls, or of bonding on another material: masonry, concrete, synthetic or other products.

 FIG. 2 illustrates an advantageous packaging of components of a micro mortier intended to be prepared according to the method described above.

 This packaging includes a bucket 1, or the like, in the bottom of which is the resin, designated by B of the epoxy composition, resin in which the glass fibers are immersed 2. A nonionic surfactant, as explained above, could be added to this resin B.

 A bucket 3 is mounted at the top of the bucket 1 so as to close it. The bottom 4 of the cup contains the hardener A intended to be poured into the resin, at the time of use. The hardener A is isolated from the upper volume 5 of the cup 3 by a waterproof film 6, in particular made of polyester or polyane, or the like. The synthetic adjuvant 7, in particular the "Meltherm", and the coloring powder 8 (metal oxide) are placed respectively in sachets 9, 10 closed in a sealed manner, and placed in the upper volume 5 of the cup. A cover 11 closes this upper volume 5 as well as the bucket 1.

 The packaging can be provided to contain the quantities of product necessary for the preparation of one m3 of finished mortar paste. In such a hypothesis, the mass of resin B contained in the bucket would be of the order of 25 kg to 50 kg; the mass of glass fibers 2 would be of the order of 20 kg to 50 kg. The amount of nonionic surfactant added to resin B would be of the order of 0.5 kg to 1 kg.

The amount of hardener A would be of the order of 25 kg to 50 kg.

The amount of coloring powder 8 would be of the order of 1 kg, while the amount of synthetic adjuvant 7 ("Meltherm") would be of the order of 10 kg to 15 kg.

 In practice, since the masses indicated above are relatively high, it is preferable to package the 3rd products for a volume of finished mortar paste of 100 liters, 50 liters or any other volume at the convenience of the users.

Claims (10)

 1. process for making a micro @@@ tier reinforced with mineral fibers. in particular of glass fibers, method se ~ n which is mixed with silica sands: a hydraulic binder, such as cement or the like; the water necessary for the hydration of the binder; and fibeo, characterized in that before introducing the hydraulic binder - an epoxy composition is prepared, separately, in an aqueous medium, the fibers t2) intended for the reinforcement of the micro mortar being incorporated into this epoxy composition - a pre-treatment is carried out -mixture of sand and epoxy composition, containing the fibers (2), - and then, only, the hydraulic binder and its water of hydration are added to the mixture thus prepared.  2. Method according to claim 1, characterized in that the fibers (2) immersed in the epoxy composition are cut to an average length of 25 mm to 30 mm.  3. Method according to claim 1 or 2, characterized in that the amount of glass fibers added is of the order of 20 kg to 50 kg of fibers per m3 of finished mortar paste.  4. Method according to any one of the preceding claims, in which the epoxy composition comprises two components, namely an epoxy resin and a hardener intended to be poured into the resin at the time of use, characterized in that the fibers 12) have been previously introduced into one of the components formed by the epoxy resin.  5. Method according to any one of the preceding claims, characterized in that a nonionic surfactant is added to the post-epoxy composition, in particular at a rate of 0.5 kg to 1 kg per m3 of mortar finished.  6. Method according to any one of the preceding claims, characterized in that before adding to the sand 1 epoxy composition, it is mixed with this sand. a synthetic adjuvant, in particular that known under the commercial name of "Meltherm".  7. Method according to claim 6, characterized in that the synthetic adjuvant is introduced at the rate of approximately 15 kg of adjuvant per 1,000 kg of sand  8. Method according to claim 6 or 7, characterized in that the synthetic adjuvant is added to dry or semi-wet sand, and, that even before adding the synthetic adjuvant, it is possible to disperse, at dry, in the sand, a metal oxide, in particular at the rate of 1 kg per 1000 kg of sand, for the purpose of coloring the micro-mortar.  9. Micro-mortar prepared according to a process according to any one of claims 1 to 8.  10. Packaging for components of a micro mortar intended to be prepared according to the method of any one of claims 1 to 8, characterized in that it comprises a bucket (1), or the like, in the bottom of which is finds the resin (B) of the epoxy composition, resin in which the fibers (2) are immersed; a bucket (3), mounted at the top of the bucket so as to close it, the bottom of this bucket containing the hardener (A) intended to be poured into the resin, this hardener being isolated from the volume located above the bucket by a waterproof film (6) or the like, while the synthetic adjuvant (7) and / or the coloring powder (8), if any, are placed in respective sachets (9, 10), placed in the upper volume of the cup, this the latter as well as the bucket being closed by a cover (11).