Chemical Transformation of Rice Husk Ash Morphology

Abstract

Rice husk ash (RHA) has significant potential to be used as a supplementary cementing material (SCM). However, RHA contains a cellular, honeycomb-like morphology of amorphous silica and this morphology results in high water absorption. Due to this morphology, the use of RHA in concrete results in reduced workability and higher water demands. Reduced workability and higher water demands can be mitigated by using smaller RHA particles. These smaller particles can be obtained by mechanical grinding. However, this grinding requires significant energy. This paper presents a novel method to transform RHA morphology using a chemical transformation process; specifically, an alkali transformation method. Results indicate that the process can effectively reduce RHA particle size and eliminate the cellular and honeycomb-like morphology.