An Experimental Investigation of Coal Bottom Ash as Sand Replacement

Abstract

The ash from burned coal that falls to the bottom of a furnace is called coal bottom ash (CBA). This ash contributes to about 20% of total coal ash, and it has been disposed of on open land and in landfills for decades, resulting in environmental pollution issues. This research investigates the potential use of coal bottom ash from the Manjung Power Plant as a substitute for sand aggregates in concrete. Therefore, an experimental investigation that includes particle size distribution, fineness modulus, specific gravity, water absorption, x-ray fluorescence (XRF), and scanning electron microscope (SEM) was carried out to determine the characteristics of coal bottom ash. The results revealed that coal bottom ash has a particle size distribution and fineness modulus comparable to that of sand particles. Both materials have rounded to angular particles with interlocking characteristics. However, coal bottom ash seems to have rough surfaces with porous particles and it is lighter than sand particles. These characteristics cause coal bottom ash to have a lower specific gravity and a high water absorption rate. Besides, coal bottom ash used in this investigation has been classified as Class C. It has pozzolanic materials and high calcium content, thus helping to improve C-S-H gels with high cementitious properties, resulting in higher strength performance. In conclusion, coal bottom ash from Manjung Power Plant has its advantages and looks like sand particles. Therefore, it has the potential to be used as a material substitute for concrete.