ECO-FRIENDLY UTILIZATION OF RICE HUSK ASH AND BAGASSE ASH BLEND AS PARTIAL SAND REPLACEMENT IN SELF-COMPACTING CONCRETE

Abstract

Self-compacting concrete (SCC) is largely used construction material worldwide, uplifting the demand of river sand along all of its constituents due to the recent construction boom. Rice husk ash (RHA) and Bagasse ash (BA) are the biomass waste of the abundantly produced crops in Pakistan, which causes several cardiovascular diseases to humans and poses threats to degrade air quality as well. Therefore, this research aims to study the effect of environmental friendly substitution of river sand with blended waste ashes of RHA and BA on microstructural, fresh, physicomechanical and sulfate resistance of SCC. The results of microstructural characterization revealed that the adsorptive natured siliceous micro-sized particles contribute toward higher water demand in SCC. The microstructural investigation of SCC mixes containing blended ashes of RHA and BA was conducted by Scanning Electron Microscopy (SEM) to find the hydration phases. Based on their calcium to silica (Ca/Si) ratios determined from Energy Dispersive X-ray Spectroscopy (EDX), the results shows the formation of secondary Calcium Silicate Hydrate (CSH) gel. The rheological properties including slump flow, J-ring, L-box, V-funnel, and air content tests were conducted in the fresh state to study its flow ability, passing ability, filling ability. The results of rheological properties revealed that the fluidity of SCC mixes reduced due to porous nature of incorporated ashes, whereas the viscosity of the mixes improved upon the incorporation of blended ashes. The physicomechanical properties include water absorption, hardened density, compressive strength, and split tensile strength. The physicomechanical properties revealed that the 20% collective replacement of incorporated waste ashes produced structural lightweight concrete with the compressive strength and hardened density values of 20MPa and 1816 Kg/m3, respectively. Conclusively, the ecofriendly utilization of blended ashes of RHA and BA improved the viscosity, physicomechanical properties and sulfate resistance of SCC.