PORTLAND CEMENT Russian patent published in 1998 - IPC

FIELD: building materials industry, more particularly production of cement. SUBSTANCE: cement comprises portland cement clinker, heat treated active mineral additive and gypsum. Said active mineral additive includes tripoli prefired at 1100-1300 C for 15- 30 minutes. The ratio of components is as follows (wt %): 75-99 portland cement clinker; 1-25 said mineral additive; 3-5 gypsum based on clinker weight. EFFECT: greater strength of element at normal water consumption and higher frost resistance thereof. 1 tbl