Abstract

Effect of SO4 in cement mixing water on the initial property of cement was estimated for cement samples prepared by adding several kinds of sulfate. With the increase of SO4, fluidity of mortar prepared by adding PC (polycarboxylic acid-based water reducing agent) was improved at the lower SO4 concentration, whereas it was depressed at the higher SO4 concentration. It is considered that the former phenomenon is mainly due to regulation of C3A hydration and the latter is by hindrance to adsoption of PC on cement particles. As the result, SO4 concentration has optimum values concerning the fluidity of PC-added mortar.