EXPANDING ADDITIVE TO CEMENT Russian patent published in 2000 - IPC

FIELD: manufacture of straining, expanding and shrinkage-free cements and concretes. SUBSTANCE: expanding additive comprises sulfoaluminate clinker in which calcium sulfoaluminate and mayonite are present at 6:1 to 5:1 ratio and finely ground corundum with specific surface of 6000 to 10.000 sq. cm/g, ratios of components being as follows, wt %; said sulfoaluminate clinker, 40-65; corundum, 40-65; and gypsum, 34-35. EFFECT: increased strength during hardening period and sulfate resistance of cement stone. 2 tbl