The use of pozzolanic materials as cementitious additives is one of the ways to reduce CO2 production during cement production and also improve the durability of cementitious materials. The purpose of the present work is to investigate the influence of Rice Husk Ash (RHA) on the performance of cement pastes in hydrochloric acid environment. For this, ash was produced by calcining rice husk at 680°C for 5 hours to produce reactive pozzolan. The chemical and mineralogical composition of the ash has been assessed by ICP-AES and XRD analyses. The results showed that the obtained ash is rich in amorphous silica with pozzolanic activity index higher than the required minimum value of 75% for pozzolanic materials. The use of RHA as an additive to cement promoted the formation of calcium silicate hydrate (CSH) and calcium aluminate hydrates such as C4AH13 and C3ASH6. The presence of RHA in the cement paste improved their resistance to hydrochloric acid attack due on one hand to the formation of supplementary CSH, resulting from the pozzolanic reaction between amorphous silica of the RHA and the portlandite released by hydration of the cement, and another hand by the filler effect of RHA.

Pozzolanic Materials, Rice Husk Ash, Cement Paste, Durability, Hydrochloric Acid