Patent ID: 8377196

Claim:
A rheology modifying admixture for a dry cast cementitious composition comprising: at least one additive (A) capable of undergoing shear thinning in dry cast cementitious compositions in response to the application of energy to said dry cast cementitious composition and recovering viscosity in the absence of an application of energy to said dry cast cementitious composition, wherein additive (A) is selected from the group consisting of polyalkylene oxides, polysaccharides, cellulose polymers, polyacrylic acid, polyamides, starch, modified starch, and mixtures thereof; and at least one additive (B) that does not undergo shear thinning when used alone in a dry cast cementitious composition in response to the application of energy to said dry cast cementitious composition, but when used in combination with additive (A), synergistically acts with additive (A) to further reduce the yield stress of said dry cast cementitious composition to which additives (A) and (B) are added, wherein additive (B) is selected from the group consisting of alkyl aryl alkoxylate, alkyl alkoxylate, halogenated surfactants, anionic surfactants, cationic surfactants, nonionic surfactants, natural resins, natural rosins, synthetic resins, synthetic rosins, ethylene oxide/propylene oxide block or random copolymers, partially hydrolyzed polyvinyl alcohol, fully hydrolyzed polyvinyl alcohol, ethoxylated acetylenic diols, and mixtures thereof, wherein said additive (A) is present in amount from about 0.0005 percent to about 0.025 percent by weight of cementitious content, and wherein said additive (B) is present in an amount from about 0.001 percent to about 0.05 percent by weight of cementitious content.