Packing Effect of a Crystalline Material with Different Particle Sizes on Heat Evolution of Pastes

Abstract

This paper investigated the heat evolution of pastes due to packing effect of a crystalline material with different particle sizes. Ground river sand was used as a crystalline material and was ground to have two different particle sizes and were used separately as a replacement of Portland cement type I at rates of 0, 50, 60, and 70% by weight of binder. Heat evolution of paste containing ground river sand was measured using an isothermal conduction calorimeter up to 72 h. In addition, the compressive strengths of mortars at the age of 24 and 74 h were investigated. The results showed that ground river sand with different particle sizes had a slight effect on the heat evolution of paste. For pastes with the same replacement rate, the heat evolution of pastes were slightly increased with the decreased of the particle size of the ground river sand. Pastes containing ground river sand with d50 of 4.8 μm and d50 of 32.2 μm at 12 and 72 h had the heat evolution due to packing effect ranging from 4.0 to 22.7 J/g. The heat evolution due to packing effect was low during the first 12 h and increased with age and was constant at the age of 24 to 72 h. The compressive
strength of mortar containing ground river sand at 50-70% developed continuously at the ages of 24 to 72 h while the cumulative of heat evolution of paste containing ground river sand tended to be constant.