Study on use of bottom ash in manufacturing cement blocks

Abstract

Bottom ash is a common by-product of thermal power plants or boilers. From an ecological and engineering point of view, the use of coal bottom ash in cement mixtures is a beneficial application. This study mainly aims to check the possibility of using bottom ash as a replacement to the fine aggregate in manufacturing 300mm×100mm×150mm solid cement blocks locally. Bottom ash from the coal-fired boiler in Sri Lanka was used to replace manufactured sand at different percentages by volume of sand. Mechanical and durability properties of cement blocks were determined at the ages of 14, 28, and 56 days. Finally, developed statistical models to predict compressive strength, water absorption, and density of cement blocks. The results showed that the density and compressive strength of cement blocks decreased, and water absorption increased with an increasing replacement level of bottom ash. From the analysis, it can be concluded that up to 45 per cent of fine aggregate in the cement blocks can be replaced with sieved coal bottom ash to produce cement blocks, which satisfy the requirements of current SLS standards.