Influence of rice husk ash on the waterproof properties of ultrafine fly ash based geopolymer

This work studies the influence of rice husk ash (RHA) on the waterproof and microstructural properties of ultrafine fly ash (UUFA) based geopolymer. Fly ash based geopolymer (FG) pastes containing different amounts of RHA were prepared and characterized. Combining with the softening coefficient, surface properties of samples, TG and FT-IR etc. tests, the mechanism was uncovered. The results indicate that not only would the specific honeycomb-hole effect and active SiO2 brought by RHA synergistically lead to the densification of structure, but also decline the existence of calcium hydroxide and promote the formation of gel, which make a significant contribution to the improvement of waterproof property. (C) 2019 Elsevier Ltd. All rights reserved.