Development of Sustainable Cement Mortar Incorporating Rice Husk Ash

Abstract

The study for the development of sustainable cement mortar incorporating rice husk ash was conducted by several approaches. Several researchers have been conducting research to replace the ordinary Portland cement by new materials with pozzolanic and cementitious properties. The aim of this study was to investigate the performance of cement mortar with rice husk ash for its sustainable development. A detail investigation was conducted to produce the rice husk ash with appropriate properties by effective incineration process. The fineness of rice husk ash based on different incineration systems, retention time and grinding time was determined. Characterization of rice husk ash was performed with XRD, SEM and chemical composition analysis. The effect of rice husk ash on heat of hydration was examined. Eventually, the performance of cement mortar with different proportions of rice husk ash was evaluated based on strength, permeability, sorptivity, salt crystallization, resistance to sulphate attack and effect of elevated temperature ranging from 200 to 700°C. The result shows that the highest fineness of 6894 cm2/gm was obtained for rice husk ash produced in laboratory burning system with 60 hours retention and 180 minutes grinding. The result of XRD confirmed the amorphous state of rice husk ash produced in laboratory burning system at 663.6°C. The maximum compressive strength of 33.09 MPa at 28 days was found for control sample. The highest compressive strengths at later age of 90, 350, 600 and 900 days were found to be 38.08, 38.80, 39.09 and 39.23 MPa respectively for 20% replacement with rice husk ash. The highest permeability of 4905 columbs was found in case of control sample at 28 days age. The result indicates that the permeability is inversely proportional to rice husk ash and curing age of sample. The trend of sorptivity was found similar to permeability and the highest value of control sample was found to be 0.214 kg/m2-min0.5. It was found that the mortar samples with 15% and 20% rice husk ash sustained up to standard 20 cycles in salt crystallization. No crack or spalling was observed due to sulphate attack on the mortar samples with 15 and 20% replacement of OPC with rice husk ash. The control sample exhibits the highest strength of 44.47 and 23.85 MPa at 200 and 700°C respectively. The sample having 15% rice husk ash shows maximum strength of 48.26 and 43.52 MPa at 300°C and 400°C respectively while the highest strength was obtained at 500°C for sample with 20% rice husk ash. The findings of the present study would contribute to the sustainable development of cement mortar incorporating rice husk ash.