Study on the Effect of Re-Burning Temperature of Rice Husk Ash on Its Activity to Use as an Active Additive for Portland Blended Cement

In this study, Cautre rice husk ash (RHA) was burned at various temperatures from 500 to 700 °C at different retention period to survey the activity of RHA to use as an active additive for Portland blended cement (PCB). The experimental results show that RHA calcined at 500 °C in 30 min has higher puzzolanic activity and improves compressive strength of cement. The RHA sample calcined at 700 °C in 30 min has suitable chemical properties and fineness according to TCVN 8827:2001, but it decreases the cement strength. The heat-treated RHA samples improve normal consistency and reduce the setting time of cement when comparing to non-heat-treated RHA one.