Hydraulic cement with accelerated high strength development

Abstract

A method of manufacturing cements based on calcium sulfoaluminate by forming a clinker through calcining a selection of typical cement precursor raw materials to temperatures of more than 1200.degree. C. in an industrial kiln, preferably with a preheater (typically of the cascading cyclone type) and precalciner, selected in such a manner that the clinker thus produced has a high content of calcium sulfoaluminate, tricalcium silicate and dicalcium silicate with no other calcium aluminates and, preferably during or prior to the grinding thereof, adding to the clinker thus produced (with the above recited basic components), effective amounts of calcium oxide or hydroxide and calcium sulfate, in order to activate said clinker. Upon said grinding, a temperature of about 100 to 125.degree. C. is to be attained for a time long enough to convert gypsum to the hemihydrate form, thus making sure that the calcium sulfate present in the thus obtained cement product is in a condition to react quickly during the hydration of said cement; thereby giving rise to the early formation of ettringite; for which the presence of a pH above 12 is needed. Also claimed is the novel activated cement resulting from the calcination and grinding methods of this invention.

Dependencies are inferred from the claim text.