Method for retarding the setting time of rapid hardening cement

摘要

This invention relates to a method for retarding the setting time of rapid hardening cement which comprises adding a boric compound to cement manufactured by adding insoluble anhydrite to clinker powder containing 11CaO.7Al.sub.2 O.sub.3.CaX.sub.2 or adding the clinker to insoluble anhydrite and intergrinding the mixture, and a method for still more retarding the setting time of rapid hardening cement which comprises adding a boric compound to cement containing a set-retarding agent other than the boric compound.