Effect of mineral additives on hydration heat of concrete mixtures

Abstract

The investigation of Portland cement with different mineral additives used for the massive concrete structures are presented in the paper. The type of cement type and ambient temperature influence on the hydration heat of concrete mixture was determined. The laboratory experiments with different additives for cement were carry out: slag up to 20% (CEM II/A-S 42,5 N), limestone up to 20% (CEM II/A-LL 42,5 R), slag from 66 to 80 % (CEM III/B 32,5 N) and without mineral additives (CEM I 42,5 R). Also the industrial experiments with designed concrete mixtures and the modeling of concrete temperature during cement hydration where carried out. The investigation of concrete mixture temperature regime during a massive concrete structure construction and curing time were performed. Cement type and mineral additives influence on the hydration heat of concrete mixture was determined. The results suggests the hydration heat of concrete mixture is highest with cement without mineral additive (CEM I 42,5 R) and the lowest with cement with the maximum amount of slag (CEM III/B 32,5 N). Modeling of heat release from hardening concrete mixture derived the use of lower activity cement with a larger amount of slag (CEM III/B 32,5 N) stands higher than the heat content of the slag with Portland cement concrete with a smaller amount of slag (CEM II/AS 42,5 N) for requiring larger quantities of cement in concrete mixture. It was found that the used retarder has not a significant effect on hydration heat of concrete mixtures with slag cement. Concrete thermal regime modeling results and temperature measurements in a concrete structure has shown that the temperature in massive concrete structure with slag cement with up to 20% slag addition reaches 61 °C. The massive concrete structures with slag additives (CEM II/A-S 42,5) can be concreted without special cooling technology in average ambient temperature under 15 °C.