Characterization of historic mortars and the effect of rice husk ash (RHA) on quicklime

Abstract

Historic mortars are minerologically characterized for many reasons pertaining to traditional building conservation. In order to determine the binding material of the historic masonary building, this material must be sufficiently separated from the aggregate. In this study, the Cas mortar (Traditional gypsum-based construction mortar in Siirt, T & uuml;rkiye) used in traditional Cas houses was characterised and compared with composite lime mortars prepared by substituting quicklime with 10 %, 15 % and 20 % rice husk ash (RHA). The mechanical properties of Cas mortar are much higher than those of lime mortars. However, when 20 % RHA was substituted for lime, it was found to significantly change the properties of the mortars, increasing the compressive and flexural strength by 68 % and 58 % respectively and improving the specific heat and many other properties. X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FT-IR) analyses showed that the 63 mu m sieved powder analysis was more accurate in determining the chemical characterisation of the historic mortars.