Anti-filming surface-active agent

Abstract

The invention relates to an anti-filming surface adjuvant for hydraulic binders comprising at least one fat and at least one anti-caking agent, to its preparation method as well as to a method for preparing a hydraulic binder composition suitable for making screeds or self-compacting concretes (SCC) including the step consisting of adding to the hydraulic binder the adjuvant according to the invention at a dosage comprised between 50 and 1,500 g/m.sup.3 of screed or of concrete.

Claims

1. A process for forming an anhydrite screed with reduced formation of a surface film at a surface of the screed compared to a screed produced without an admixture, comprising: preparing an anhydrous calcium sulfate (anhydrite) mortar composition; and adding water and an admixture to the anhydrite mortar composition to form a screed; wherein the screed comprises the admixture of 40-60% by dry weight of at least one fatty alcohol and 60-40% by dry weight of at least one anti-caking agent, wherein an amount of the admixture in the screed is between 50 and 1,500 g/m.sup.3, wherein the screed does not comprise Portland cement; whereby the screed exhibits reduced formation of the surface film compared to screeds produced without the admixture.

2. The process according to claim 1, wherein the fatty alcohol is a primary fatty alcohol.

3. The process according to claim 1, wherein the fatty alcohol includes 8 to 22 carbon atoms.

4. The process according to claim 2, wherein the fatty alcohol is hexadecan-1-ol or octadecan-1-ol.

5. The process according to claim 4, wherein the anti-caking agent has an average particle size comprised between 0.01 and 100 m.

6. The process according to claim 1, wherein the anticaking agent is a carbonate, silicate or oxide.

7. The process according to claim 6, wherein the anticaking agent is calcium carbonate, kaolin, alumina or silica.

8. The process according to claim 1, wherein the anticaking agent is a mineral or organic coloring agent.

9. The process according to claim 1, wherein the admixture comprises a colored anticaking agent.

10. The process according to claim 1, wherein the admixture is in the form of powder.

11. The process according to claim 1, wherein the admixture is added to the anhydrite before the water for mixing.

12. A process according to claim 1, wherein the at least one fatty alcohol and the at least one anti-caking agent are each added as a powder to the anhydrite.

13. A process for preparing an anhydrite mortar composition, the method consisting of: (i) preparing an admixture by mixing: at least one fatty alcohol; at least one anti-caking agent, and one or more additional ingredients selected from the group consisting of an antifoam agent, a plasticizer and a setting modifier, wherein the admixture comprises 40 to 60% by weight of fatty alcohol and 60 to 40% by weight of anti-caking agent, and an amount of the admixture in the screed is between 50 and 1,500 g/m.sup.3; and (ii) adding said admixture to the anhydrite mortar composition, wherein the anhydrite mortar composition comprises anhydrous calcium sulfate, sand, dispersant and water, and wherein the anhydrite mortar composition does not contain Portland cement.

14. The process according to claim 13, wherein the admixture is added to the anhydrite mortar composition in the absence of water.

15. A process for preparing an anhydrite mortar composition consisting of: (ii) preparing an admixture by mixing components consisting of: at least one fatty alcohol; at least one anti-caking agent, and one or more additional ingredients selected from the group consisting of an antifoam agent, a plasticizer and a setting modifier, wherein the admixture comprises 40 to 60% by weight of fatty alcohol and 60 to 40% by weight of anti-caking agent, and an amount of the admixture in the screed is between 50 and 1,500 g/m.sup.3; and (ii) adding said admixture to the anhydrite mortar composition, wherein the anhydrite mortar composition consists of anhydrous calcium sulfate, sand, dispersant and water.

Description

EXAMPLES

Example 1: Composition and Making of an Anhydrite Screed

(1) In a kneader of the Rayneri type, a mortar with admixtures, based on anhydrous calcium sulfate is prepared, having the composition indicated in Table 1 below by following the following mixing procedure: Dry homogenization of the sand at low speed between 0-30 seconds; Prehumidification of the sand with of total water between 30-60 seconds, and then stopping the kneader; At 300 seconds, introduction of the anhydrous calcium sulfate with the admixture according to the invention and homogenization between 300-330 seconds at low speed; Adding the remainder of the water with the dispersants between 330 and 390 seconds; Kneading at low speed between 390 and 420 seconds; Stopping the kneader for scraping the edges and the bottom of the bowl with a trowel between 420-450 seconds; and Kneading at high speed between 450 and 510 seconds.

(2) TABLE-US-00001 TABLE 1 Mortar composition based on anhydrous calcium sulfate. Component Amount Anhydrous calcium sulfate 650 kg/m.sup.3 0/4 mm sand from Bernieres (France) 1,350 kg/m.sup.3 Dispersant (Chryso Fluid Premia 196, 0.27% by weight* sold by CHRYSO, France) Water 280 kg/m.sup.3 *As a liquid based on the amount of anhydrous calcium sulfate

(3) The spreading measured with the cone (.sub.upper=7 cm, .sub.lower=10 cm, height=6 cm) immediately after preparation was 26010 mm. The thereby produced mortar is cast into square molds with oblique edges oiled beforehand with dimensions 40*40 cm so as to produce mortar slabs, and the surface of said mortar is subject to the passing of a bar for debubbling and leveling in order to obtain a smooth surface.

Example 2: Composition and Making of a Cement Screed

(4) In a kneader of the Rayneri type, a mortar with admixtures, based on cement, is prepared having the composition indicated in Table 2 below, by following the following mixing procedure: Dry homogenization of the sand at low speed between 0-30 seconds; Prehumidification of the sand with of total water between 30-60 seconds, and then stopping the kneader; At 300 seconds, introduction of the cement and of the filler with the admixture according to the invention and homogenization between 300-330 seconds at low speed; Addition of the remainder of the water with the dispersant between 330 and 390 seconds; Kneading at low speed between 390 and 420 seconds; Stopping the kneader for scraping the edges and the bottom of the bowl with a trowel between 420-450 seconds; and Kneading at high speed between 450 and 510 seconds.

(5) The spread measured with the cone (.sub.upper=7 cm, .sub.lower=10 cm, height=6 cm) immediately after preparation is 26010 mm. The thereby produced mortar is cast into square molds with oblique edges oiled beforehand with dimensions 40*40 cm so as to produce mortar slabs, and the surface of the mortar is subject to the passing of a bar for debubbling and leveling in order to obtain a smooth surface.

(6) TABLE-US-00002 TABLE 2 Cement-based mortar composition Component Amount Cement of the CEM I type 280 kg/m.sup.3 Durcal 10 filler (sold by OMYA, France) 380 kg/m.sup.3 Sand from Bernieres (France) 1,280 kg/m.sup.3 Dispersant (CHRYSO Fluid Optima 100, 1.2% by weight* sold by CHRYSO, France) Water 260 kg/m.sup.3 *as a liquid based on the amount of binder (cement + filler)

Example 3: Composition and Making of a Self-Compacting Concrete (SCC)

(7) In a kneader of the Skako Couvrot type, an SCC with admixtures is prepared having the composition indicated in Table 3 below by following the following mixing procedure: Dry homogenization of the sand and of the gravel at low speed between 0-30 seconds; Prehumidification of the sand with of the total water of the whole of the granules between 30-60 seconds, and then stopping the kneader; At 300 seconds, introduction of the cement and of the filler with the admixture according to the invention and dry kneading between 300-330 seconds; Addition of the remainder of the water with the superplasticizer between 330 and 390 seconds; and Stopping the kneader at 510 seconds.

(8) The spread measured with the standardized cone (Abrams cone) of the concrete immediately after preparation is 70010 mm. The thereby produced concrete is cast into square molds with oblique edges oiled beforehand with dimensions 40*40 cm so as to produce concrete slabs, and the surface of the concrete is subject to the passing of a bar for debubbling and leveling in order to maintain a smooth surface.

(9) TABLE-US-00003 TABLE 3 Self-compacting concrete composition Component Amount Cement of the CEMI type 280 kg/m.sup.3 Erbray filler (sold by OMYA, France) 160 kg/m.sup.3 0/4 sand from Bernieres (France) 887 kg/m.sup.3 6/10 gravel from Villermain (France) 160 kg/m.sup.3 9/18 gravel from the Loire (France) 653 kg/m.sup.3 Dispersant (CHRYSO Fluid OPTIMA 350, 0.7% by weight* sold by CHRYSO, France) Water 213 kg/m.sup.3 *as a liquid based on the amount of binder (cement + filler).

Comparative Example 4: No Admixture

(10) In order to evaluate the effect of the admixture according to the invention, a slab was prepared according to Example 1, without the admixture according to the invention.

(11) A portion of the obtained slabs was evaluated as such, without any treatment (Example 4A) while another portion was subject to sanding (Example 4B).

Comparative Example 5: Fat Alone

(12) In order to evaluate the affect of the admixture according to the invention, a mortar slab was prepared according to example 1 by further adding a mixture of 66% by weight of 1-hexadecanol and 33% by weight of 1-octadecanol marketed as NAFOL 1618 by SASOL (with D.sub.5040 m).

(13) The fatty alcohol is introduced during the kneading at the same time as the hydraulic binder in an amount of 250 g/m.sup.3 as indicated in Tables 4 and 5.

Example 6: Fat and Anti-Caking Agent

(14) In order to evaluate the effect of the admixture according to the invention, a mortar slab was prepared according to Example 1 with additional addition of a mixture of 50% by weight of a mixture of 66% by weight of 1-hexadecanol and 33% by weight of 1-octadecanol and marketed as NAFOL 1618 by SASOL (with a D.sub.5040 m) and of 50% by weight of calcium carbonate (D.sub.501.5 m).

(15) The admixture according to the invention is introduced during the kneading at the same time as the hydraulic binder, in an amount of 500 g/m.sup.3 as indicated in Tables 4 and 5.

Comparative Example 7: Fat and Shrinkage Reducing Agent

(16) In order to evaluate the effect of the admixture according to the invention, a mortar slab was prepared according to Example 1 with further addition of a mixture of 66% by weight of 1-hexadecanol and 33% by weight of 1-octadecanol marketed as NAFOL 1618 by SASOL (with a D.sub.5040 m) and 2% by liquid of CHRYSOSerenis (a shrinkage reducing agent marketed by CHRYSO, France).

(17) The fatty alcohol is introduced during the kneading at the same time as the hydraulic binder, in an amount of 250 g/m.sup.3 as indicated in Tables 4 and 5.

(18) Evaluation of the Adherence

(19) After 7 days, ceramic stoneware tiles with a size of 5050 mm are stuck on the surface of the slabs obtained in Examples 4 to 7 above by means of a tile adhesive mortar (adhesive LANKO Prolidal Plus 5024 marketed by PAREX LANKO). This adhesive mortar is applied according to the NF EN 1348 standard which consists of: spreading the adhesive mortar with a comb having square teeth 555 mm; depositing a load of 2 kg for 25 to 35 seconds on each tile during the adhesive bonding, 9 tiles being stuck per slab; drying the adhesive mortar for 21 days at room temperature (according to the conditions of the NF EN 1348 standard); sticking removal tees on the ceramic tiles by means of an epoxy glue (LANKO 723, marketed by PAREX LANKO); and removing the tiles one day later via the tees by measuring the required force with a dynamometer of the Dynatest type.

(20) A fracture between two materials assembled by adhesive bonding may propagate in two ways: either inside the adhesive joint or the support (screed or concrete): this is then a cohesive failure, or at the surface and this is then referred to as an adhesive failure.

(21) A cohesive failure indicates that the interface has behaved more strongly than the core of the adhesive or of the support (screed or concrete). Conversely, for an adhesive failure, the interface was weaker.

(22) The failure mode (either adhesive or cohesive), as well as the traction force required for removing the tiles from the slabs provide an evaluation of the adherence capacity of the surfaces. The obtained results are grouped in Table 4 below.

(23) It is seen that adherence is very weak for slabs without admixtures without any sanding treatment. Moreover, during the carrying out of the tests, better dispersion of the fatty alcohol in the screed is visually observed, when it is associated with the anti-caking agent.

(24) It is seen that the admixture according to the invention allows covering of a surface with a traction stress close to that of a sanded surface, with a very clear economical advantage.

(25) Moreover, it is noted that the association of a fatty alcohol with a shrinkage reducing agent increases the surface film and thereby further reduces the tensile stress of the surface.

(26) TABLE-US-00004 TABLE 4 Evaluation of the adherence Tensile stress Dosage in [MPa]/Failure EXAMPLE Admixtures/Treatment g/m.sup.3 mode 4A No admixture, non sanded 0.4 MPa/adhesive 4B No admixture, sanded 2.0 MPa/cohesive 5 Non-anti-caked fatty 250 g/m.sup.3 Inhomogeneous alcohol results due to poor dispersion of the product in the screed 6 Fatty alcohol + CaCO.sub.3 500 g/m.sup.3 1.6 MPa/cohesive 7 Fatty alcohol + shrinkage 250 g/m.sup.3 0.6 MPa/adhesive reducing agent
Evaluation of the Surface Hardness

(27) In order to evaluate the effect of the admixture according to the invention on the surface hardness, the slabs prepared in Examples 4 to 7 were tested by means of a device called a Perfotest type CSTB.

(28) The Perfotest device allows reproducible impacts to be produced on horizontal surfaces. It is equipped with a 5-dihedra punch intended for measuring the hardness of a coating of class P2 and P3. According to the height at which the punch is released, a different force is applied, P3 being greater than P2. The results are expressed as a number of detached, degraded or intact squares. Thus, the larger the number of intact squares, the greater is the surface hardness or less the surface film is present, both for a classification of type P2 and of type P3. The tests are directly conducted at the surface of the slabs free of any surface coating. The measurements are conducted 4 times in different locations on each slab both on the tests of type P2 and of type P3.

(29) The results of the test are recorded in the Table 5 below.

(30) It is seen that the surface hardness is very low for slabs without any addition of the admixture according to the invention without any sanding treatment. Moreover, when conducting the tests, better dispersion of the fatty alcohol in the screed is visually observed when it is associated with the anti-caking agent.

(31) Moreover, the association of a fatty alcohol with a shrinkage reducing agent increases the surface film and thus further reduces the surface hardness.

(32) TABLE-US-00005 TABLE 5 Evaluation of the surface hardness EXAMPLE Admixtures/Treatment Dosage in g/m.sup.3 Surface hardness 4A No admixture according to invention, non sanded 4B No admixture + according to invention, sanded 5 Fatty alcohol 250 g/m.sup.3 Inhomogeneous results due to poor dispersion of the product in the screed 6 Fatty alcohol + CaCO.sub.3 500 g/m.sup.3 ++ 7 Fatty alcohol + 250 g/m.sup.3 shrinkage reducing agent

(33) The admixture according to the invention therefore allows a notable improvement in the surface hardness and the adherence capacity of surfaces of hydraulic binders based on cement or on calcium sulfate while being easily dispersible and stable upon storage.