Impurity inerting composition
A method for inerting clays in sands which are intended for the preparation of hydraulic compositions, the method including a step of adding to the hydraulic composition, or to one of the constituents thereof, a composition which may include at least 50% by weight of a cationic polymer which has a density of cationic charges which is greater than 0.5 meq/g and an intrinsic viscosity which is less than 1 dl/g as an active substance. The hydraulic composition may be a concrete or a mortar.
1. A method for inerting clays in sands used in the preparation of a hydraulic composition, comprising the steps of: adding the sands to the hydraulic composition, the sands having a clay content of from 0.5 to 5% by weight, and adding a composition to the hydraulic composition, or to one of the constituents thereof, the composition comprising at least 50% by weight of a cationic polymer having a density of cationic charges greater than 0.5 meq/g and an intrinsic viscosity less than 1 dl/g as an active substance.
2. A method according to claim 1 , wherein the hydraulic composition is a concrete or a mortar.
3. A method according to claim 1 , wherein the hydraulic composition contains no superplasticiser.
4. A method according to claim 1 , wherein the composition is added to the hydraulic composition or to one of the constituents thereof by spraying.
5. A method according to claim 1 , wherein the composition is used in a quarry.
6. A method according to claim 1 , wherein the composition is used in a concrete mixing plant.
7. A method according to claim 1 , wherein the cationic polymer has a density of cationic charges greater than 2 meq/g.
8. A method according to claim 1 , wherein the cationic polymer has an intrinsic viscosity less than 0.6 dl/g.
9. A method according to claim 1 , wherein the composition further comprises an anionic polymer.
10. A method according to claim 9 , wherein the composition comprises a maximum of 50% by weight of anionic polymer as an active substance.
11. A method according to claim 9 , wherein at least one of the cationic and anionic polymers has a comb structure.
12. A method according to claim 1 , wherein the cationic polymer is linear.
13. A method according to claim 1 , wherein the cationic polymer comprises cationic groups of quarternary amine.
14. A method according to claim 1 , wherein the cationic polymer is prepared by condensation of epichlorohydrin with a dialkylamine.
15. A method according to claim 14 , wherein the dialkylamine is dimethylamine.
16. A method according to claim 9 , wherein the anionic polymer contains carboxylic groups.
17. A method according to claim 9 , wherein the anionic polymer further comprises polyether groups.
18. A method according to claim 1 , wherein the polymer is obtainable by condensation of dicyandiamide with formaldehyde, in the presence of:
A) a polyalkylene glycol.
19. A method according to claim 1 , wherein the polymer is obtainable by condensation of dicyandiamide with formaldehyde, in the presence of:
B) a polyalkoxylated polycarboxylate.
20. A method according to claim 1 , wherein the polymer is obtainable by condensation of dicyandiamide with formaldehyde, in the presence of:
C) an ammonium derivative.
21. A method according to claim 1 , wherein the polyalkylene glycol has the following formula (I):
R 2 —O—[R 2 —O] n —R 3
where:
R 1 is an alkyl group of C 1 to C 4 ;
R 2 and R 3 are, independently of each other, a hydrogen atom or an alkyl group of C 1 to C 4 ; and
n is a number from 25 to 1000.
22. A method according to claim 1 , wherein the molar ratio between formaldehyde and dicyandiamide is in the range of from 0.8:1 to 4:1.
23. A method according to claim 18 , wherein the polyalkylene glycol is a polyethylene glycol.
24. A method according to claim 19 , wherein the polyalkoxylated polycarboxylate has the following formula (II):
where:
R 1 and R 2 are, independently of each other, a hydrogen atom or a methyl group;
R 3 and R 4 are, independently of each other, an alkylene group of C 1 to C 4 ;
R 5 is a hydrogen atom or an alkyl group of C 1 to C 4 ;
m is a whole number from 2 to 100;
p is a whole number from 2 to 100; and
q is a whole number from 2 to 100.
25. A method according to claim 19 , wherein the polyalkoxylated polycarboxylate has an ester level of from 10 to 60%.
26. A method according to claim 20 , wherein the ammonium ion of the ammonium derivative has the following formula (IV):
NH(R 6 ) 3 +
where:
the R 6 groups are identical or different and represent H or an alkyl group of C 1 to C 6 .
27. A method according to claim 20 , wherein the ammonium derivative is ammonium chloride, ammonium sulphate, ammonium iodide, ammonium bromide, ammonium acetate.
28. A method according to claim 20 , wherein the molar ratio between the compound C and the dicyandiamide is from 1 to 1.5.
29. A method according to claim 1 , wherein the composition is in the form of an aqueous solution.