Effects of RHA on autogenous shrinkage of Portland cement pastes

In this work, the effects of partial replacements of Portland cement by rice-husk ash (RHA) on the autogenous shrinkage were investigated. Pastes with water/binder ratio 0.30 and substitutions of 5% and 10% cement by RHA were tested. Two RHAs, both amorphous and partially crystalline, were studied. Comparisons between pastes with silica fume, and control pastes (without RHA or silica fume) are presented. Autogenous deformations, internal relative humidity and compressive strength were recorded. The RHA, amorphous or partially crystalline, when used in an appropriate way, reduces autogenous shrinkage.