COMPOSITION FOR GYPSUM ARTICLE PREPARING Russian patent published in 1995 - IPC

FIELD: industry of building materials. SUBSTANCE: composition involves the following components, wt.-% lignosulfonates 4-12; compound of hexavalent chrome 0.25-2.25; boron water soluble compound (as B₂O₃ 0,14-1,25) 0.14-1.25; sulfate of alkaline or alkaline-earth metal 0.25-2.75, and calcium sulfate β-semihydrate the rest. Properties of composition: mechanical strength at dry state is 19.5-24.3 MPa, at wet state is 17.6-22.1 MPa, softening coefficient is 0.85-0.9; hardness at dry state is 29.2-36.4 MPa, at wet state is 26.3-33.0 MPa. EFFECT: enhanced water resistance, hardness and strength. 2 tbl