Replacement of conventional fine aggregate with bottom ash in geopolymer concrete

The commonly used fine aggregate in concrete and mortar is river sand. The steep demand of river sand for infrastructure development is faced with problems of availability, its quality and rising cost. Large scale exploitation of sand is becoming a major concern. Conventional fine aggregate for concrete needs replacement for economic, environmental and ecological benefits.

To overcome thepresent crisis, an investigation is made by replacingtheriver sand with bottom ash (BA)in geopolymer concrete (GC). The specimens used in the studies of GC issynthesised from fly ash (FA) of three different originsat ambient temperature with alkali activators of different concentrations. Workability and bleeding of fresh concrete are studied. It has been observed that the compressive strength and split tensile strength of third origin of FA based GC was better as compared to first and second origin FA based GC, which can be correlated with higher glass content. Considering the fresh and hardened properties of GC, the BAcontentwas optimisation at 10% of mix proportion.