Copolymers for treating construction aggregates
View Patent ↗The present invention provides methods, admixture compositions for treating clay-bearing aggregates used for construction purposes, and aggregate compositions for construction purposes. The clay-bearing aggregates are treated with a cationic copolymer made from two and preferably three different monomer components. Cementitious compositions containing the treated aggregates are also described.
1. A composition comprising: a plurality of clay-bearing sand aggregates and
(i) a water-reducer or superplasticizer admixture; and
(ii) at least one copolymer obtained from monomer components (A), (B), and optionally (C), as follows:
(A) a first monomer selected from quarternized vinylpyridine or other cationic monomer represented by the following structures
wherein
R 1 , R 2 , and R 3 each independently represent hydrogen, —CH 3 , or —COOH;
R 4 , R 5 , R 6 , R 7 , and R 8 each independently represent a C 1 -C 4 alkyl group;
R 9 and R 10 each independently represent hydrogen or —CH 3 ;
Z 1 represents —O—or —NH—;
Y 1 represents —CH 2 CH(OH)CH 2 — or (CH 2 ) n wherein “n” represents an integer of 0 to 6; and
X represents a halide, pseudohalide, or sulfate;
(B) a second monomer represented by the structural formula
wherein
R 11 , R 12 , R 13 , R 14 , and R 15 each independently represent hydrogen or C 1 to C 3 alkyl;
Z 2 represents —O—, —COO—, —OOC—, —COHN—, or —NHCO—;
Y 2 represents —(CH 2 ) n — wherein “n” represents an integer of 0 to 6; and
“m” represents an integer of 10 to 200; and
(C) a third monomer selected from the group consisting of acrylate, methacrylate, acrylamide, methacrylamide, alkyl or dialkyl acrylamide, and methacrylamide monomers.
2. The composition of claim 1 further comprising a cement binder.
3. The composition of claim 1 wherein the copolymer has a molecular weight of 1,000-100,000.
4. The composition of claim 1 wherein the copolymer has a molecular weight of 2,000-60,000.
5. The composition of claim 1 wherein the copolymer has a molecular weight of 5,000-50,000.
6. The composition of claim 1 wherein, in the second monomer component, “m” represents an integer of 10-100.
7. The composition of claim 1 wherein, in the second monomer component, “m” represents an integer of 20-70.
8. The composition of claim 1 wherein the molar ratio (A:B) of said first monomer component (A) to the second monomer component (B) is 0.20:0.80 to 0.90:0.10.
9. The composition of claim 8 wherein the molar ratio (A:B) of the first monomer component (A) to said second monomer component (B) is 0.50:0.50 to 0.85:0.15.
10. The composition of claim 1 wherein each of R 7 and R 8 are —CH 3 groups, and each of R 9 and R 10 are hydrogen.
11. The composition of claim 1 wherein Z 1 is oxygen and Y 1 is —CH 2 CH 2 —.
12. The composition of claim 1 wherein Z 1 is —NH— and Y 1 is —CH 2 CH 2 CH 2 —.
13. The composition of claim 1 wherein the copolymer has two or more monomer components which are represented by one of the structures of the first monomer component (A).
14. The composition of claim 1 wherein the copolymer has two or more monomer components which are represented by the structure of the first monomer component (B).
15. The composition of claim 1 wherein the copolymer has a Brookfield viscosity of 20 to 2000 cps at 70 wt % aqueous solution at 20° C.
16. The composition of claim 15 wherein the copolymer has a Brookfield viscosity of 60 to 500 cps at 70 wt % aqueous solution at 20° C.
17. The composition of claim 1 wherein the amount of the copolymer introduced to the clay-bearing sand aggregates is 10% to 40% by weight based on the weight of the clay contained in the clay-bearing sand aggregates.
18. The composition of claim 17 wherein the amount of the copolymer introduced to the clay-bearing sand aggregates is 10% to 30% by weight based on the weight of the clay contained in the clay-bearing sand aggregates.
19. The composition of claim 1 wherein the copolymer is introduced to the clay-bearing sand aggregates separately, followed by addition of a water reducing admixture.
20. The composition of claim 1 wherein the copolymer is introduced to the clay-bearing sand aggregates together with an EO/PO polycarboxylate superplasticizer.