The Effects of Silicate Structures on Hydration of Pozzolanic Materials

Abstract

The blended cement has been positively used in Japan, because of environmental problems and useful recycling of industrial wastes have been considered in recent years. Not only blast-furnace slags known as hydraulic materials, but also fly-ash and fumed silica that have character of pozzolanic activity are effectively used. The pozzolanic activity is generally confirmed by quantitative measurement of calcium hydroxide consumed in hydrated binder mixtures. On the other hand, the calcium silicate hydrates (C-S-H) value generated by the hydration estimated from the residual values, in which unhydrous cement clinker and crystalline hydrates are subtracted from whole hydrates, is not accurate. The authors have reported a study of changes in silicate anion structures of hydraulic binders, such as ordinary portland cement (OPC) and pulverized blastfurnace slags, during hydration using trimethylsililation (TMS) method. In this study, the pozzolanic reaction of the pastes mixed with fly-ash and calcium hydroxide are studied in terms of mechanisms of their influences on silicate anion structures by use of TMS method. We clarified difference between the reaction of hydraulic materials such as OPC / blast-furnace slags and of pozzolanic materials such as fly-ash from analytical results of silicate anion structures of C-S-H in detail. Furthermore, the activation of pozzolanic reaction of fly-ash with heating is related to the formation of C-S-H.