Air management in cementitious mixtures having plasticizer and a clay-activity modifying agent
View Patent ↗An exemplary surface active agent admixture composition of the invention comprises (1) a first surface active agent comprising a betaine, an alkyl or aryl or alkylaryl sulfonate, or mixture thereof; and (2) a second surface active agent comprising a nonionic oxyalkylene-containing polymer surfactant. The present invention therefore provides a system for ensuring the presence in a hydratable cementitious composition (when hardened) a sufficient air volume and sufficient air void fineness and consistency. Further exemplary admixture compositions may comprise one or more plasticizers and one or more clay activity-modifying agents. Cementitious compositions and methods for modifying cementitious compositions, which incorporate the above-mentioned surface active agent combination, are also described. The invention provides the ability to adjust and stabilize air void systems in hydratable cementitious compositions, while allowing conventional air entraining agent (AEA) dosage practices to be followed.
1. A hydratable cementitious composition containing a cementitious binder and an admixture composition, said admixture composition comprising: a plasticizer for modifying a cementitious composition; a first surface active agent comprising a betaine, an alkyl sulfonate, an aryl sulfonate, an alkylaryl sulfonate, or a mixture thereof; and a second surface active agent comprising a nonionic oxyalkylene-containing polymer surfactant represented by at least one of the formulae “A” through “D”:
wherein x and x′ independently represent an integer of from 1 to 140; and y represents an integer of from 15-70;
wherein v and v′ independently represent an integer of from 9 to 27; and w represents an integer of from 4 to 232;
wherein q, q′, q″, and q′″ independently represent an integer of from 4 to 31; and r, r′, r″, and r′″ independently represent an integer of from 2 to 140; and
wherein m, m′, m″, and m′″ independently represent an integer of from 1 to 95; and n, n′, n″, and n′″ independently represent an integer of from 8 to 32.
2. The hydratable cementitious composition of claim 1 wherein said first surface active agent is a betaine represented by the formula
wherein R 1 , R 2 , and R 3 are independently alkyl groups or alkyl containing moieties; x is 1 to 5; and M is a metal cation, or ammonium.
3. The hydratable cementitious composition of claim 2 wherein, in said betaine formula, said metal cation is sodium.
4. The hydratable cementitious composition of claim 2 wherein said betaine is in the form of a metal salt.
5. The hydratable cementitious composition of claim 2 wherein, in said betaine, R 1 and R 2 represent C1-C4 alkyl groups and R 3 represents a C 10 -C 28 alkyl group or C 10 -C 28 alkyl-containing moiety.
6. The hydratable cementitious composition of claim 2 wherein, in said betaine, R 3 represents a C 10 -C 20 alkylamido propyl group.
7. The hydratable cementitious composition of claim 6 wherein said betaine is cocoamido propyl betaine.
8. The hydratable cementitious composition of claim 1 wherein said betaine is a sulfobetaine having the general formula
wherein R 1 , R 2 , and R 3 are independently alkyls or alkyl containing moieties, x is an integer of 1 to 5, M is a metal cation, and Y is hydrogen or a hydroxyl group.
9. The hydratable cementitious composition of claim 8 wherein said sulfobetaine is cocoamido propyl hydroxy sultaine.
10. The hydratable cementitious composition of claim 9 wherein said ethylene oxide (EO) and propylene oxide (PO) groups are in an EO/PO ratio of 0.1 to 0.2.
11. The hydratable cementitious composition of claim 1 wherein said nonionic oxyalkylene polymer surfactant is represented by Formula A.
12. The hydratable cementitious composition of claim 1 further comprising, in addition to said plasticizer, at least one other admixture comprising a water reducer, a set accelerator, a set retarder, a shrinkage reducer, a corrosion inhibitor, a strength enhancer, or mixture thereof.
13. The hydratable cementitious composition of claim 12 wherein said plasticizer or other admixture comprises an air entraining group or moiety having polycarboxylic acid groups or their salts or esters, oxyalkylene groups, or a mixture thereof.
14. The hydratable cementitious composition of claim 13 wherein said plasticizer or other admixture comprises a comb polymer having a carbon containing backbone to which are attached pendant groups comprising polycarboxylic acid groups or their salts or esters; oxyalkylene groups; or a mixture thereof.
15. The hydratable cementitious composition of claim 1 further comprising at least one clay activity-modifying agent.
16. The hydratable cementitious composition of claim 15 wherein said at least one clay activity-modifying agent comprises a gluconate, a polyoxyalkylene alcohol, or mixture thereof.
17. The hydratable cementitious composition composition of claim 1 wherein said first surface active agent comprises a betaine; and said admixture composition comprises a plasticizer or other admixture comprising a polycarboxylic acid group or its salt or ester, and at least one clay activity-modifying agent.
18. The hydratable cementitious composition of claim 1 further comprising at least one air entraining agent.
19. The hydratable cementitious composition of claim 18 wherein said air entraining agent is selected from the group consisting of water soluble salts of wood resins, wood rosins, lignosulfonic acid, sulfonated hydrocarbons, proteinaceous materials, fatty acids and their esters, non-ionic surfactants, sulfonated hydrocarbons, and proteinaceous materials.
20. The hydratable cementitious composition of claim 18 wherein said air entraining agent comprises tall oil fatty acid.
21. The hydratable cementitious composition of claim 1 further comprising at least one aggregate comprising fine aggregate, coarse aggregate, or mixture thereof; said cementitious composition, when combined with water and allowed to harden, having a uniformly distributed air void system having (A) a spacing factor less than 0.008 inch as measured in accordance with ASTM C457-98, and (B) a specific surface greater than 600 (1/inch) as measured in accordance with ASTM C457-98.