What Type and How Much of Pozzolans We Should Use in High Strength Mass Concrete?

Hydration heat and strength development at early ages of thirteen mixtures with water-cement ratios of 0.3 and 0.46 were studied. Natural pozzolan and fly ash were used, as partial replacement for cement, in the mixtures. In 0.3 water cement ratio specimens, cement was replaced with silica fume at three percentages of 5, 8 and 11. Hydration heat characteristics of the specimens were determined via a semi adiabatic calorimeter and 4C-Heat software. The results showed that as water cement ratio decreased, heat evolution per 1 kg cementing materials was also decreased. It was concluded that fly ash, as a convenient pozzolan, reduced the hydration heat but increased the strength development.