AQUEOUS POLYMER COMPOSITION AND COPOLYMER

Abstract

The invention relates to an aqueous composition comprising a copolymer obtained by a specific polymerisation reaction using an anionic monomer comprising a polymerisable olefinic unsaturation and a carboxylic acid function and a monomer of formula (I):

##STR00001##

The invention also relates to said copolymer, to a method for the production thereof, and to the use of same as a superplasticizing agent.

Claims

1: An aqueous composition comprising at least one copolymer, the polymolecularity index P.sub.I of which is less than 3, obtained by at least one radical polymerisation reaction in water and at a temperature ranging from 10 to 90° C.: (a) of at least one anionic monomer comprising at least one polymerisable olefinic unsaturation and at least one carboxylic acid group and (b) of at least one monomer of formula (I): ##STR00007## wherein: R.sup.1 and R.sup.2, identical or different, independently represent H or CH.sub.3, L.sup.1 independently represents a group selected from the group consisting of CH.sub.2, CH.sub.2—CH.sub.2 and O—CH.sub.2—CH.sub.2—CH.sub.2—CH.sub.2, L.sup.2 independently represents a group selected from the group consisting of (CH.sub.2—CH.sub.2O).sub.x, (CH.sub.2CH(CH.sub.3)O).sub.y, (CH(CH.sub.3)CH.sub.2O).sub.z and combinations thereof and x, y and z, identical or different, independently represent an integer or decimal between 0 and 150 and the sum of x+y+z is between 10 and 150, in the presence: (i) of from 0.05 to 5% by weight, with respect to the amount of monomers, of at least one compound of formula (II): ##STR00008## wherein: X independently represents H, Na or K and R independently represents a C.sub.1-C.sub.5 alkyl group and (ii) of at least one radical-generating compound selected from the group consisting of hydrogen peroxide, ammonium persulphate, an alkali metal persulphate, and mixtures or associations thereof with ammonium bisulphite, with an alkali metal bisulphite or with an ion selected from the group consisting of Fe.sup.II, Fe.sup.III, Cu.sup.I, Cu.sup.II.

2: The composition according to claim 1, comprising no homopolymer of monomer (a) or comprising a reduced, small or very small amount by weight of homopolymer of monomer (a) with respect to the amount by dry weight of copolymer.

3: The composition according to claim 1, wherein the polymerisation reaction uses: from 1 to 25% by weight of monomer (a) and from 75 to 99% by weight of monomer (b).

4: The composition according to claim 1, wherein the copolymer comprises: from 1 to 25% by weight of monomer (a) and from 75 to 99% by weight of monomer (b).

5: The composition according to claim 1, comprising less than 2,000 ppm by weight of residual monomer (a) with respect to the amount by dry weight of copolymer.

6: The composition according to claim 1, wherein the monomer (a) used is selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, an acrylic acid salt, a methacrylic acid salt, an itaconic acid salt, a maleic acid salt and mixtures thereof.

7: The composition according to claim 1, wherein x is strictly greater than y+z.

8: The composition according to claim 1, wherein the radical polymerisation reaction in water is performed at a temperature ranging from 30 to 85° C.

9: The composition according to claim 1, wherein the polymerisation reaction also uses another anionic monomer.

10: The composition according to claim 1, wherein the polymerisation reaction also uses at least one other monomer (c) selected from the group consisting of: another anionic monomer, a non-ionic monomer comprising at least one polymerisable olefinic unsaturation, 2-acrylamido-2-methylpropanesulphonic acid, a salt of 2-acrylamido-2-methylpropanesulphonic acid, 2-(methacryloyloxy)ethanesulphonic acid, a salt of 2-(methacryloyloxy)ethanesulphonic acid, sodium methallyl sulphonate, styrene sulphonate and mixtures thereof.

11: A copolymer, the polymolecularity index P of which is less than 3, obtained by at least one radical polymerisation reaction in water and at a temperature ranging from 10 to 90° C.: (a) of at least one anionic monomer comprising at least one polymerisable olefinic unsaturation and at least one carboxylic acid group and (b) of at least one monomer of formula (I): ##STR00009## wherein: R.sup.1 and R.sup.2, identical or different, independently represent H or CH.sub.3, L.sup.1 independently represents a group selected from the group consisting of CH.sub.2, CH.sub.2—CH.sub.2 and O—CH.sub.2—CH.sub.2—CH.sub.2—CH.sub.2, L.sup.2 independently represents a group selected from the group consisting of (CH.sub.2—CH.sub.2O).sub.x, (CH.sub.2CH(CH.sub.3)O).sub.y, (CH(CH.sub.3)CH.sub.2O).sub.z and combinations thereof and x, y and z, identical or different, independently represent an integer or decimal between 0 and 150, in the presence: (i) of from 0.05 to 5% by weight, with respect to the amount of monomers, of at least one compound of formula (II): ##STR00010## wherein: X independently represents H, Na or K and R independently represents a C.sub.1-C.sub.5 alkyl group and (ii) of at least one radical-generating compound selected from the group consisting of hydrogen peroxide, ammonium persulphate, an alkali metal persulphate, and mixtures or associations thereof with ammonium bisulphite, with an alkali metal bisulphite or with an ion selected from the group consisting of Fe.sup.II, Fe.sup.III, Cu.sup.I, Cu.sup.II.

12: The copolymer according to claim 11, comprising: from 1 to 25% by weight of monomer (a) and from 75 to 99% by weight of monomer (b).

13: A formulation comprising: at least one aqueous composition according to claim 1, at least one hydraulic binder, optionally water, optionally at least one aggregate, optionally at least one admixture.

14: The formulation according to claim 13, comprising: from 0.01 to 5% by dry weight of copolymer, respectively in the form of the at least one aqueous composition, and from 95 to 99.9% by dry weight of at least one hydraulic binder.

15: The formulation according to on claim 13, comprising water in an amount by weight, with respect to the amount by weight of the hydraulic binder, of less than 0.7.

16: A method for changing the rheology of a hydraulic formulation, comprising adding at least one aqueous composition according to claim 1 to the hydraulic formulation.

17: A method for controlling the workability of a hydraulic formulation, comprising adding at least one aqueous composition according to claim 1 to the hydraulic formulation.

18: The method for controlling workability according to claim 17, wherein the workability of the hydraulic formulation is kept constant for at least 1 hour.

19: A method for reducing the setting time of a hydraulic formulation, comprising adding at least one aqueous composition according to claim 1 to the hydraulic formulation.

Description

EXAMPLES

Example 1: Preparation of Copolymers According to the Invention and of a Comparative Copolymer

Example 1.1: Copolymer (P1) According to the Invention

[0324] Water (50 g), iron sulphate heptahydrate (0.11 g), a 60% by mass solution in water (271.92 g) of monomer (b15) with a molecular mass of 2,400 g/mol, a comonomer (maleic anhydride) (9.71 g), a 50% by mass aqueous solution of sodium hydroxide (15.35 g) and a 20% by mass solution in water (2.68 g) of DPTTC are placed in a stirred reactor. The reactor is heated to 58±3° C. Hydrogen peroxide is added in a 35% by mass aqueous solution (5.6 g).

[0325] Then, for 2 hours, a mixture of water (30 g) and of acrylic acid (22.65 g), a mixture of water (25 g), of a 60% by mass solution in water (32.7 g) of a monomer (b15) with a molecular mass of 2,400 g/mol and of a 20% by mass solution in water (10.0 g) of DPTTC are simultaneously injected into the reactor, along with a mixture of water (55 g) and a 40% by mass aqueous solution of sodium bisulphite (5.64 g), with this latter mixture injected in 2 hours and 15 minutes.

[0326] The reactor is kept at a temperature of 58±3° C. for 1 hour.

[0327] The product is cooled and then partially neutralised by adding a 50% by mass aqueous solution of sodium hydroxide (22.3 g). The aqueous polymeric solution comprises less than 900 ppm of residual dry acrylic acid with respect to the total amount of dry copolymer.

[0328] A copolymer (P1) is obtained comprising 10.5% by weight of acrylic acid, 85.0% by weight of monomer (b15) and 4.5% by weight of maleic anhydride. It has a molecular mass M.sub.W of 51,000 g/mol and a polymolecularity index P of 1.9.

Example 1.2: Copolymer (P2) According to the Invention

[0329] Water (50 g), iron sulphate heptahydrate (0.11 g), a 60% by mass solution in water (271.92 g) of a monomer (b15) with a molecular mass of 2,400 g/mol and a 20% by mass solution in water (2.54 g) of DPTTC are placed in a stirred reactor. The reactor is heated to 35±2° C. Hydrogen peroxide is added in a 35% by mass aqueous solution (5.6 g). Then, for 1 hour and 15 minutes, a mixture of water (30 g) and of acrylic acid (32.26 g) and a mixture of a 60% by mass solution in water (32.7 g) of monomer (b15) with a molecular mass of 2,400 g/mol, of water (30 g) and of a 20% by mass solution in water (10.15 g) of DPTTC are simultaneously injected into the reactor, along with a mixture of water (55 g) and sodium bisulphite (5.64 g), with this latter mixture injected in 1 hour and 40 minutes.

[0330] The reactor is kept at a temperature of 35±2° C. for 1 hour and 30 minutes. The product is cooled and then partially neutralised by adding a 50% by mass aqueous solution of sodium hydroxide (36 g). The aqueous polymeric solution comprises less than 1,430 ppm of residual dry acrylic acid with respect to the total amount of dry copolymer. A copolymer (P2) is obtained comprising 14.5% by weight of acrylic acid and 85.5% by weight of monomer (b15). It has a molecular mass M.sub.W of 129,800 g/mol and a polymolecularity index P.sub.1 of 2.0.

Example 1.3: Copolymer (P3) According to the Invention

[0331] Water (50 g), iron sulphate heptahydrate (0.11 g), a 60% by mass solution in water (264.56 g) of a monomer (b15) with a molecular mass of 2,400 g/mol and a 20% by mass solution in water (2.54 g) of DPTTC are placed in a stirred reactor. The reactor is heated to 55±2° C. Hydrogen peroxide is added in an aqueous solution at 35% by mass (5.6 g). Then, for 1 hour and 15 minutes, a mixture of water (30 g) and of acrylic acid (32.49 g) and a mixture of a 60% by mass solution in water (32.7 g) of monomer (b15) with a molecular mass of 2,400 g/mol, a mixture of water (16 g) and of a 20% by mass solution in water (10.15 g) of DPTTC are simultaneously injected into the reactor along with a mixture of water (55 g) and ammonium persulphate (2.26 g), with this latter mixture injected in 1 hour and 40 minutes.

[0332] The reactor is kept at a temperature of 55±2° C. for 1 hour and 30 minutes.

[0333] The product is cooled and then partially neutralised by adding a 50% by mass aqueous solution of sodium hydroxide (34.8 g). The aqueous polymeric solution comprises less than 130 ppm of residual dry acrylic acid with respect to the total amount of dry copolymer.

[0334] A copolymer (P3) is obtained comprising 15.4% by weight of acrylic acid and 84.6% by weight of monomer (b15). It has a molecular mass M.sub.W of 54,200 g/mol and a polymolecularity index P.sub.I of 1.7.

Example 1.4: Copolymer (P4) According to the Invention

[0335] Water (240 g) and a 20% by mass solution in water (3.0 g) of DPTTC are placed in a stirred reactor. The reactor is heated to 65±2° C.

[0336] Then, for 3 hours, a mixture of water (10 g), of acrylic acid (22.88 g) and of a 60% by mass solution in water (782.52 g) of monomer (b15) with a molecular mass of 2,400 g/mol, a mixture of water (40 g) and of a 20% by mass solution in water (12.0 g) of DPTTC are simultaneously injected into the reactor along with a mixture of water (65 g) and ammonium persulphate (6.09 g).

[0337] The reactor is kept at a temperature of 65±2° C. for 1 hour.

[0338] The product is cooled and then partially neutralised by adding a 50% by mass aqueous solution of sodium hydroxide (1.3 g). The aqueous polymeric solution comprises less than 40 ppm of residual dry acrylic acid with respect to the total amount of dry copolymer.

[0339] A copolymer (P4) is obtained comprising 4.6% by weight of acrylic acid and 95.4% by weight of monomer (b15). It has a molecular mass M.sub.W of 55,100 g/mol and a polymolecularity index .sub.pI of 1.4.

Example 1.5: Copolymer (P5) According to the Invention

[0340] Water (10 g), iron sulphate heptahydrate (0.11 g), a 60% by mass solution in water (318 g) of a monomer (b3) of formula (I) wherein L.sup.2 represents a combination (CH.sub.2—CH.sub.2O).sub.x, (CH.sub.2CH(CH.sub.3)O).sub.y and (CH(CH.sub.3)CH.sub.2O).sub.z, x represents 42 and y+z represents 15.5, with a molecular mass of 3,000 g/mol, and a 20% by mass solution in water (2.03 g) of DPTTC, are placed in a stirred reactor. The reactor is heated to 58±3° C.

[0341] Hydrogen peroxide is added in a 35% by mass aqueous solution (4.48 g).

[0342] Then, for 2 hours, a mixture of water (50 g) and of acrylic acid (20.14 g), a mixture of a 20% by mass solution of DPTTC (8.12 g) and water (40 g) and a mixture of water (55 g) and of a 40% by mass aqueous solution of sodium bisulphite (4.51 g) are simultaneously injected into the reactor, with this latter mixture injected in 2 hours and 15 minutes.

[0343] The reactor is then kept at a temperature of 58±3° C. for 1 hour.

[0344] The product is cooled and then partially neutralised by adding a 50% by mass aqueous solution of sodium hydroxide until pH 7.5 is reached. The aqueous polymeric solution comprises less than 1,500 ppm of residual dry acrylic acid with respect to the total amount of dry copolymer.

[0345] A copolymer (P5) is obtained with a molecular mass by weight of 60,820 g/mol and a polymolecularity index P.sub.I of 1.2.

Example 1.6: Copolymer (P6) According to the Invention

[0346] Water (10 g), iron sulphate heptahydrate (0.11 g), a 60% by mass solution in water (318 g) of a monomer (b3) of formula (I) wherein L.sup.2 represents a combination (CH.sub.2—CH.sub.2O).sub.x, (CH.sub.2CH(CH.sub.3)O).sub.y and (CH(CH.sub.3)CH.sub.2O).sub.z, x represents 52 and y+z represents 11, with a molecular mass of 3,000 g/mol, and a 20% by mass solution in water (2.03 g) of DPTTC, are placed in a stirred reactor. The reactor is heated to 58±3° C.

[0347] Hydrogen peroxide is added in a 35% by mass aqueous solution (4.48 g).

[0348] Then, for 2 hours, a mixture of water (50 g) and of acrylic acid (20.14 g), a mixture of a 20% by mass solution of DPTTC (8.12 g) and water (40 g), and a mixture of water (50 g) and 40% by mass aqueous solution of sodium bisulphite (4.51 g) are simultaneously injected into the reactor, with this latter mixture injected in 2 hours and 15 minutes.

[0349] The reactor is then kept at a temperature of 58±3° C. for 1 hour.

[0350] The product is cooled and then partially neutralised by adding a 50% by mass aqueous solution of sodium hydroxide until pH 7.5 is reached. The aqueous polymeric solution comprises less than 910 ppm of residual dry acrylic acid with respect to the total amount of dry copolymer.

[0351] A copolymer (P6) is obtained with a molecular mass by weight of 46,190 g/mol and a polymolecularity index P.sub.I of 1.3.

Example 1.7: Copolymer (P7) According to the Invention

[0352] Water (145 g), iron sulphate heptahydrate (0.11 g), a monomer (b19) with a molecular mass of 2,400 g/mol (191 g), and a 20% by mass solution in water (2.54 g) of DPTTC are placed in a stirred reactor. The reactor is heated to 58±3° C.

[0353] Hydrogen peroxide is added in a 35% by mass aqueous solution (5.6 g).

[0354] Then, for 2 hours, a mixture of water (30 g) and of acrylic acid (20.14 g), a mixture of a 20% by mass solution of DPTTC (10.2 g) and of water (55 g) are simultaneously injected into the reactor along with a mixture of water (55 g) and ammonium persuplhate (2.6 g).

[0355] The reactor is then kept at a temperature of 58±3° C. for 1 hour.

[0356] The product is cooled and then partially neutralised by adding a 50% by mass aqueous solution of sodium hydroxide until pH 7.3 is reached. The aqueous polymeric solution comprises less than 25 ppm of residual dry acrylic acid with respect to the total amount of dry copolymer.

[0357] A copolymer (P7) is obtained with a molecular mass by weight of 62,700 g/mol and a polymolecularity index P.sub.I of 2.2.

Example 1.8: Copolymer (P8) According to the Invention

[0358] Water (10 g), iron sulphate heptahydrate (0.11 g), a 60% by mass solution in water (318 g) of a monomer (b3) of formula (I) wherein R.sup.1 represents CH.sub.3, R.sup.2 represents H, L.sup.1 represents CH.sub.2, L.sup.2 represents a combination (CH.sub.2—CH.sub.2O).sub.x, (CH.sub.2CH(CH.sub.3)O).sub.y and (CH(CH.sub.3)CH.sub.2O).sub.z, x represents 42 and y+z represents 15.5, with a molecular mass of 3,000 g/mol, and a 20% by mass solution in water (2.54 g) of DPTTC, are placed in a stirred reactor. The reactor is heated to 65±3° C.

[0359] Hydrogen peroxide is added in a 35% by mass aqueous solution (5.6 g).

[0360] Then, for 2 hours, a mixture of water (50 g) and of acrylic acid (20.14 g), a mixture of a 20% by mass solution of DPTTC (10.15 g) and of water (40 g) are simultaneously injected into the reactor along with a mixture of water (55 g) and ammonium persuplhate (2.26 g).

[0361] The reactor is kept at a temperature of 65±1° C. for 1 hour.

[0362] The product is cooled and then partially neutralised by adding a 50% by mass aqueous solution of sodium hydroxide until pH 7.2 is reached. The aqueous polymeric solution comprises less than 810 ppm of residual dry acrylic acid with respect to the total amount of dry copolymer.

[0363] A copolymer (P8) is obtained with a molecular mass by weight of 51,600 g/mol and a polymolecularity index P.sub.I of 1.3.

Example 1.9: Copolymer (P9) According to the Invention

[0364] Water (160 g), iron sulphate heptahydrate (0.11 g), a monomer (b19) with a molecular mass of 2,400 g/mol (194.6 g), and a 20% by mass solution in water (2.03 g) of DPTTC are placed in a stirred reactor. The reactor is heated to 65±1° C.

[0365] Hydrogen peroxide is added in a 35% by mass aqueous solution (4.48 g).

[0366] Then, for 2 hours, a mixture of water (30 g) and of acrylic acid (20.55 g), a mixture of a 20% by mass solution of DPTTC (8.12 g) and of water (50 g) and a mixture of water (55 g) and a 40% by mass solution of sodium bisulfite are simultaneously injected into the reactor.

[0367] The reactor is kept at a temperature of 65±1° C. for 1 hour.

[0368] The product is cooled and then partially neutralised by adding a 50% by mass aqueous solution of sodium hydroxide until pH 7.2 is reached. The aqueous polymeric solution comprises less than 43 ppm of residual dry acrylic acid with respect to the total amount of dry copolymer. A copolymer (P9) is obtained with a molecular mass by weight of 68,100 g/mol and a polymolecularity index P.sub.I of 2.3.

Example 1.10: Copolymer (P10) According to the Invention

[0369] Iron sulphate heptahydrate (0.11 g), a 60% by mass solution in water (318 g) of a monomer (b3) of formula (I) wherein R.sup.1 represents CH.sub.3, R.sup.2 represents H, L represents CH.sub.2, L.sup.2 represents a combination (CH.sub.2—CH.sub.2O).sub.x, (CH.sub.2CH(CH.sub.3)O).sub.y and (CH(CH.sub.3)CH.sub.2O).sub.z, x represents 52 and y+z represents 11, with a molecular mass of 3,000 g/mol, and a 20% by mass solution in water (2.54 g) of DPTTC, are placed in a stirred reactor. The reactor is heated to 65±1° C.

[0370] Hydrogen peroxide is added in a 35% by mass aqueous solution (5.6 g).

[0371] Then, for 2 hours, a mixture of water (50 g) and of acrylic acid (20.14 g), a mixture of a 20% by mass solution of DPTTC (10.15 g) and of water (40 g) and a mixture of water (50 g) and of ammonium persuplhate (2.26 g) are simultaneously injected into the reactor.

[0372] The reactor is then kept at a temperature of 65±1° C. for 1 hour.

[0373] The product is cooled and then partially neutralised by adding a 50% by mass aqueous solution of sodium hydroxide until pH 7.5 is reached. The aqueous polymeric solution comprises less than 25 ppm of residual dry acrylic acid with respect to the total amount of dry copolymer.

[0374] A copolymer (P10) is obtained with a molecular mass by weight of 53,390 g/mol and a polydispersity index of 2.1.

Example 1.11: Copolymer (P11) According to the Invention

[0375] Iron sulphate heptahydrate (0.11 g), a 60% by mass solution in water (318 g) of a monomer (b3) of formula (I) wherein R.sup.1 represents CH.sub.3, R.sup.2 represents H, L represents CH.sub.2, L.sup.2 represents a combination (CH.sub.2—CH.sub.2O).sub.x, (CH.sub.2CH(CH.sub.3)O).sub.y and (CH(CH.sub.3)CH.sub.2O).sub.z, x represents 52 and y+z represents 11, with a molecular mass of 3,000 g/mol, and a 20% by mass solution in water (2.54 g) of DPTTC, are placed in a stirred reactor. The reactor is heated to 65 PC.

[0376] Hydrogen peroxide is added in a 35% by mass aqueous solution (5.6 g).

[0377] Then, for 1 hour, a mixture of water (50 g) and of acrylic acid (20.14 g), a mixture of a 20% by mass solution of DPTTC (10.15 g) and of water (40 g) and a mixture of water (50 g) and ammonium persuplhate (2.26 g) are simultaneously injected into the reactor.

[0378] The reactor is kept at a temperature of 65±1° C. for 1 hour.

[0379] The product is cooled and then partially neutralised by adding a 50% by mass aqueous solution of sodium hydroxide until pH 7 is reached. The aqueous polymeric solution comprises less than 10 ppm of residual dry acrylic acid with respect to the total amount of dry copolymer.

[0380] A copolymer (P11) is obtained with a molecular mass by weight of 56,460 g/mol and a polymolecularity index P.sub.1 of 1.2.

Example 1.12: Copolymer (P12) According to the Invention

[0381] Iron sulphate heptahydrate (0.088 g), a 60% by mass solution in water (362 g) of a monomer (b15) with a molecular mass of 2,400 g/mol, a 20% by mass solution in water (2.54 g) of DPTTC, and 50 g of water are placed in a stirred reactor. The reactor is heated to 65±1° C.

[0382] Hydrogen peroxide is added in a 35% by mass aqueous solution (5.6 g).

[0383] Then, for 1 hour, a mixture of water (40 g), of acrylic acid (31.17 g) and of methacrylic acid (7.8 g), a mixture of a 20% solution of DPTTC (8.12 g) and water (50 g), and a mixture of water (50 g) and of a 40% solution of sodium metabisulphite (4.51 g) are simultaneously injected into the reactor.

[0384] The reactor is then kept at a temperature of 65±1° C. for 1 hour.

[0385] The product is cooled and then partially neutralised by adding a 50% by mass aqueous solution of sodium hydroxide until pH 7.1 is reached. The aqueous polymeric solution comprises less than 667 ppm of residual dry acrylic acid with respect to the total amount of dry copolymer and 5 ppm of residual methacrylic acid with respect to the total amount of dry polymer.

[0386] A copolymer (P12) is obtained with a molecular mass by weight of 81,090 g/mol and a polymolecularity index P.sub.I of 1.2.

Example 1.13: Comparative Copolymer

[0387] Water (50 g), a 60% by mass solution in water (432.53 g) of monomer (b15) with a molecular mass of 2,400 g/mol and DMDO (1,8-dimercapto-3,6-dioxaoctane) (0.62 g) are placed in a stirred reactor. The reactor is heated to 37±2° C. Hydrogen peroxide is added in a 35% by mass aqueous solution (5.6 g).

[0388] Then, for 1 hour and 15 minutes, a mixture of water (30 g) and of acrylic acid (29.47 g), a mixture of water (25 g), a 60% by mass solution in water (32.7 g) of monomer (b15) with a molecular mass of 2,400 g/mol and DMDO (4.93 g) and a mixture of water (55 g) and a 40% by mass solution in water (5.64 g) of sodium bisulphite are simultaneously injected into the reactor, with this latter mixture injected in 1 hour and 40 minutes.

[0389] The reactor is kept at a temperature of 37±2° C. for 1 hour and 30 minutes.

[0390] The product is cooled and then partially neutralised by adding a 50% by mass aqueous solution of sodium hydroxide (32.5 g). The aqueous polymeric solution comprises more than 12,000 ppm of residual dry acrylic acid with respect to the total amount of dry copolymer. Moreover, nearly 60% by weight of monomer (b15) did not react.

Example 1.14: Comparative Copolymer

[0391] Water (50 g), iron sulphate heptahydrate (0.11 g), a 60% by mass solution in water (264.56 g) of monomer (b15) with a molecular mass of 2,400 g/mol and DMDO (1,8-dimercapto-3,6-dioxaoctane) (0.62 g) are placed in a stirred reactor. The reactor is heated to 37±2° C. Hydrogen peroxide is added in a 35% by mass aqueous solution (5.6 g).

[0392] Then, for 1 hour and 15 minutes, a mixture of water (30 g) and of acrylic acid (32.49 g), a mixture of water (25 g), a 60% by mass solution in water (32.7 g) of monomer (b15) with a molecular mass of 2,400 g/mol and DMDO (4.93 g) and a mixture of water (55 g) and a 40% by mass solution in water of sodium bisulphite (5.64 g) are simultaneously injected into the reactor, with this latter mixture injected in 1 hour and 40 minutes.

[0393] The reactor is kept at a temperature of 37±2° C. for 1 hour and 30 minutes.

[0394] The product is cooled and then partially neutralised by adding a 50% by mass aqueous solution of sodium hydroxide (36.6 g). The aqueous polymeric solution comprises more than 12,000 ppm of residual dry acrylic acid with respect to the total amount of dry copolymer. Moreover, nearly 20% by weight of monomer (b15) did not react.

Example 2: Assessment of Water-Reducing Properties in a Mortar

[0395] Mortar formulations, the composition of which is shown in Table 1, are prepared according to the following procedure: [0396] incorporating the admixture and the water in the bowl of an automatic Perrier mixer for standardised cements and mortars, [0397] incorporating all the fines (cement and/or hydraulic binders), [0398] mixing at a slow speed of 140 rpm, [0399] incorporating the sand after 30 seconds, [0400] mixing at a slow speed of 140 rpm for 60 seconds, [0401] pausing for 30 seconds and cleaning the sides of the bowl, [0402] mixing at a slow speed of 140 rpm for 90 seconds.

[0403] Similarly, a comparative formulation (CF) of mortar is prepared comprising no copolymer.

[0404] The water-reducing properties of the copolymers according to the invention are assessed using the mortar formulations.

[0405] The T0 workability of the mortars formulated with the copolymers according to the invention was assessed by measuring the slump flow in accordance with standard EN 12350-2 adapted to mortar (Abrams mini-cone test).

[0406] To perform the slump flow test, the cone filled with formulated mortar is lifted perpendicular to a horizontal plate while rotating it one-quarter turn. The slump is measured with a ruler after 5 minutes across two 90° diameters. The result of the slump test is the average of the 2 values to ±/−1 mm. The tests are conducted at 20° C. The admixture content is determined such that a target slump of 220 mm±/−5 mm can be reached. The content is expressed in % by dry weight with respect to the weight of the hydraulic binder or the mixture of hydraulic binders. The results are shown in Table 1.

TABLE-US-00001 TABLE 1 According to the invention Formulation CF F1-1 F1-3 AFNOR sand (g) 1,350 1,350 1,350 CEM I 52.5N VICAT cement (g) 450 450 450 Copolymer (% by dry weight/ / P2 (0.09) P3 (0.10) dry weight of cement) Anti-foaming agent (%/admixture) / 0.5 0.5 Water (g) 266 200 200 Water/cement weight ratio 0.59 0.44 0.44 T0 workability 220 220 220 Water reduction (%) 0 25 25

[0407] The use of the copolymers according to the invention makes it possible to reduce the amount of water in the hydraulic formulation by 25% while maintaining an initial slump level (workability) similar to that of the comparative formulation comprising no copolymer.

[0408] The copolymers according to the invention can therefore be qualified as highly water-reducing agents according to standard ADJUVANT NF EN 934-2. Indeed, they make it possible to reduce the water in the admixed mortar by at least 12% with respect to the control mortar.

Example 3: assessment of water-reducing properties in Concrete

[0409] Concrete formulations (300 kg/m3) are prepared in accordance with standard NF EN 480-1 by mixing standardised sand (0/4), cement (CEM I 52.5N Vicat), 4/11 and 11/22 gravel, water and an anti-foaming agent in a mixer along with copolymer according to the invention. Similarly, a comparative concrete formulation is prepared comprising no copolymer. The proportions of each of the ingredients in the hydraulic formulations prepared are shown in Table 2.

[0410] The water/cement weight ratio is adjusted so as to preserve an initial workability similar to that of the comparative concrete formulation.

[0411] The hydraulic formulations have a uniform appearance, with no segregation of the ingredients.

[0412] The initial slump level (T0 workability) and the water reduction in the hydraulic formulations are shown in Table 2.

[0413] The initial slump level (or T0 workability) is tested at ambient temperature, using a bottomless, frustoconical cone made of galvanised steel, known as an Abrams cone, in accordance with standard EN 12350-2. This cone has the following characteristics: [0414] upper diameter: 100±2 mm, [0415] lower diameter: 200±2 mm and [0416] height: 300±2 mm.

[0417] The cone is placed on a moistened horizontal plate and filled with a set amount of each of the formulations. Filling takes two minutes. The contents of the cone are tamped down with a metallic rod.

[0418] When the cone is full, it is lifted vertically, allowing its contents to slump onto the plate. The concrete formulations can be classified with respect to their workability in accordance with standard EN 206-1.

[0419] The amount of water reduction is measured in accordance with standard ADJUVANT NF EN 934-2. The results obtained for the various hydraulic formulations are shown in Table 2.

TABLE-US-00002 TABLE 2 According to the invention Formulation CF F1-4 F1-1 Sand (kg) 32.6 32.6 32.6 4/11 gravel (kg) 12.4 12.4 12.4 11/22 gravel (kg) 29.1 29.1 29.1 Cement 12 12 12 Copolymer (% by dry weight/ / P1 (0.21) P2 (0.23) dry weight of cement) Anti-foaming agent (%/admixture) / 0.5 0.5 Water (g) 7,706 5,778 5,778 Water/cement weight ratio 0.64 0.48 0.48 T0 workability 220 220 225 Water reduction (%) 0 25 25

[0420] The use of the copolymers according to the invention makes it possible to reduce the amount of water in the hydraulic formulation by 25% while maintaining an initial slump level (workability) similar to that of the comparative hydraulic formulation.

[0421] The copolymers according to the invention can therefore be classed as highly water-reducing agents according to standard ADJUVANT NF EN 934-2. Indeed, they make it possible to reduce the water in the admixed concrete by at least 12% with respect to the control concrete.