Reply to the discussion by Ayhan Demirbas of the paper “Study on the pozzolanic properties of rice husk ash by hydrochloric acid pretreatment”

Abstract

In this article, Feng et al reply to a brief commentary on their recent study (Feng et al, 2004) on the pozzolanic properties of rice husk ash by hydrochloric acid pretreatment. In the study, the heat evolution and the hydration heat of cement, the Ca(OH)2 content in the mortar and the pore size distribution of mortar were determined. The results showed that pozzolanic activity of rice husk ash (RHA) is not only stabilized but also enhanced by pretreatment. In the commentary, Demirbas noted that the very high surface area of RHA increases its pozzolanic activity to compete with those of much finer admixtures. Demirbas called for additional attention on the chemical effects of pozzolanic materials on crystal formation during the hydration. Demirbas also referred readers to another study in which the pozzolanic properties of hydrochloric acid-treated RHA were systematically investigated (Yalcin and Sevinc, 2001). In their reply, the study authors agree with the comment that the chemical effects of pozzolanic materials on crystal formation and development during hydration should be expanded. The authors also provide some additional details regarding the pore distribution of rice husk ashes. They conclude by stressing that many more studies of this agricultural waste material need to be carried out.