Blended cements consisting of Portland cement–slag–silica fume–metakaolin system

Abstract

In the present study, hydration of four-compound systems consisting of Portland cement and three supplementary cementitious materials : silica fume, blast-furnace slag, and metakaolin, has been investigated by means of isothermal calorimetry and thermal analysis. Substitution of Portland cement was achieved at 25, 30, and 35 mass% by cementitious supplementary materials. Owing to the high specific surface, the silica fume eventuated in more distinctive demonstration of pozzolanic reactions. It decreased C/S ratio and led to the formation of hydration phases with C/S ≅ 1, which is demonstrated by wollastonite crystallization at higher temperatures. Enhanced formation of gehlenite hydrate was proved by DTG when blended cements included higher content of metakaolin and blast-furnace slag. Pozzolanic materials increased the compressive strength of particular blended samples and thus overcame the dilution effect especially at long term of curing. Presented quaternary blended samples in comparison with ordinary Portland cement thus allowed the formation of more thermal stable hydration products and can be considered as promising materials for the development of special concrete also for hydrothermal applications.