Mechanical behaviour of self compacting concrete: Effect of wood ash and coal ash as partial cement replacement

Self- compacting concrete, also referred to as self-consolidating concrete, is able to flow and consolidate under its own weight and is cohesive enough to fill spaces of almost any size and shape without segregation or bleeding, thereby, making it very suitable wherever placing is difficult. As cement manufacturing releases about 7% of CO2 into the atmosphere which is one of the major cause of global warming, therefore, the main aim of this research is to develop SCC with locally available waste materials i.e. coal ash and wood ash, and to optimize the percentage partial cement replacement to achieve strength similar to normal concrete for a particular water-to-cement (wjc) ratio. The wjc ratios of 0.50, 0.45 and 0.42 have been considered in this study, wherein, all components are kept the same for SCC except the percentage partial cement replacement by coal ash and wood ash with the chemical admixtures adjusted for obtaining the self- compaction in concrete. It was observed that all SCC mixes without any cement replacement by coal ash and wood ash exhibited greater values in both split tensile and compressive strength compared to normal concrete. The optimum percentage of partial cement replacement in SCC by both wood ash and coal ash to achieve strength similar to that of conventional normal concrete at a particular w/c ratio was found to be 10%. Hence, this study finds cement replacement by wood ash and coal ash (up to 10%) to be eco-friendly and a sustainable alternative to conventional concrete. (C) 2020 Elsevier Ltd. All rights reserved.