Patent ID: 6670415
Filing Date: 2003-12-30
Classification: C04B

Abstract:
An admixture composition comprising:(A) a comb polymer operative to plasticize a hydratable cementitious composition, said comb polymer having pendant groups comprising ethylene oxide (EO), propylene oxide groups (PO), or mixture thereof; said comb polymer capable of being absorbed by smectite clay which expands when in contact with water and thereupon absorbs said comb polymer; and (B) an agent operative to modify clay activity to minimize said absorption of said comb polymer, said agent being selected from the group consisting of an inorganic cation selected from the group consisting of magnesium, aluminum, iron, K+, NH4+, Cs+, Rb+, and Fr+; an organic cation selected from the group consisting of (i) an organic group bonded to a cationic salt group selected from phosphonium, pyridinium, sulfonium and quaternary ammonium; and (ii) an organic compound containing a single cationic amine salt group; a polar organic molecule selected from the group consisting of an oxyalkylene having a different molecular structure from said plasticizer of component A, a crown ether, a polyvinyl alcohol, a polyacrylic acid having a molecular weight of 2,000 or less, a polymethacrylic acid having a molecular weight of 2,000 or less, a polyacrylate having a molecular weight of 2,000 or less, and a polymethacrylate having a molecular weight of 2,000 or less; and a clay dispersant operative to reduce absorptivity of said clay, said dispersant comprising a polyphosphate.