Abstract: A dispersant composition for use in gypsum and/or cementitious compositions that includes, in combination, a polycarboxylate-based superplasticizer and a synergistically effective amount of an aluminum salt. The presence of the aluminum salt, such as aluminum chlorohydrate, improves the performance of the polycarboxylate-based superplasticizer.

Abstract: The present invention provides a plaster composition that includes calcined gypsum and a naphthalene sulfonate-aldehyde condensate alkali salt polymer having a weight average molecular weight from about 17,000 to about 47,000. The present invention also provides a method of forming a plaster composition that includes belending calcined gypsum and a naphthalene sulfonate-aldehyde condensate alkali salt polymer having a weight average molecular weight from about 17,000 to about 47,000 together to form a dry blend and contacting the dry blend with water to form a hardenable aqueous slurry.

Abstract: The present invention provides a dispersant composition that is obtained by condensing an aldehyde, preferably formaldehyde, with a sulfonated middle fraction obtained from the distillation of coal tar. The middle fraction, prior to sulfonation, includes greater than 55% to about 95% by weight naphthalene and from about 5% to less than 45% by weight of a plurality of compounds selected from the group consisting of quinoline, indene, biphenyl, indane, acenaphthene, anthracene, phenanthrene, methyl naphthalene, cresol, phenol, xylenol, and tetralin. The condensation product is reacted with a base such as sodium hydroxide to form a salt polymer having a weight average molecular weight between about 2,000 and 40,000. Salt polymers formed in accordance with the method of the invention are useful as dispersants and plasticizers in aqueous cementitious slurries.