The effects of temperature to reactive powder concrete in construction

Reactive powder concrete (RPC) is an ultra-high performance concrete which has good mechanical properties and durability. The major difference between RPC and the conventional concrete is that no coarse aggregate is involved in RPC, but the use of crushed quartz and quartz sand instead with high dosage of silica fume. Heat treatment is a well known method that can further improve the performance of RPC. This paper examines the optimal duration under heat treatment with each pre-determined temperature for RPC. Heat treatment with temperature of 100°C, 150°C, 200°C and 250°C and durations of 8 hours, 16 hours and 24 hours are used for testing. It is found that when the heat-treatment temperature increases, the optimal duration for maximizing compressive strength will be longer. The heat-treatment temperature is also positively correlated with compressive strength of RPC. The microstructural behaviour of the effect on heat-treatment temperature and duration on compressive strength are explored by scanning electron microscope (SEM) and energy dispersive x-ray spectroscopy (EDX). It is shown that the heating duration has a positive effect on the quality and quantity of crystal formation while heating temperature has the effect on the types of crystal formed.