Characterisation and pore structure analysis of mortar incorporating valorised rice husk ash

Abstract

Physical, chemical, and mineralogical characterisation of as-received rice husk ash (RHA) samples sourced from four rice-growing regions (North, South, East, and West) of India is presented. Valorised RHA was obtained through controlled combustion at two temperature ranges (600–700 °C and 650–700 °C) of husks from the North in an industry set up. Valorisation efficacy has been tested through comparative characterisation of the valorised RHAs with the as-received RHAs from the four regions. Blending of 15% valorised RHA (in the beneficiated state) by weight of cement had no adverse effect on compressive strength even though water–binder ratio of the blended mortar had to be increased by 14% to achieve flow of the control cement mortar. Compared with the control cement mortar, porosity of the mortar blended with the beneficiated RHA measured using mercury intrusion porosimetry (MIP) increased by up to 10% primarily due to an increase in the number of large mesopores (0.01–0.05 µm).