Composition and method for retarding the setting of cements

摘要

A retarding agent for cement consists essentially of in percent by weight: }CaF2 50 - 65 }Ca3(PO4)2 7 - 12 }CaSO4 5 - 7.5 }SiO2 10 - 20 }Fe2O3 1 - 2 }Al2O3 1 - 5, } this retarding agent is preferably the insoluble residue by-product obtained by dissolving raw phosphate with an inorganic acid. It retards the setting of cement at high ambient temperatures, and can be used as well with sea water or with fresh water in the making of concrete and the like.