Utilization of Coal Bottom Ash as Replacement of Cement in Concrete: A Review & Preliminary Results

Abstract

Coal bottom ash (CBA) is a secondary product of coal industry and is produced in large extent from coal thermal power plants. Utilization of CBA in the manufacturing of concrete proposes economic and ecological way of its disposal. Simultaneously, its usage conserves the natural resources and promotes sustainability. This paper describes a brief literature review on the utilization of CBA incorporated in place of Portland cement (PC). Also, the study includes the preliminary experimental results of concrete containing CBA as replacement of PC and Natural fine aggregates (NFA). Besides from review of literature two most vital durability tests (rapid chloride penetration, capillary water absorption) and one parental mechanical test (compressive strength) were performed. The aforesaid durability tests directly measure the ingression of chemicals and water absorption by capillarity which primarily depend on the overall porosity and size of pores in concrete, while the compressive strength test measures the overall quality of concrete. The research needs along with the comparison of literature and experimental results are also presented. The findings show that chloride permeation decreases and water absorption increases with increasing incorporation level of CBA. The increasing levels of CBA enhance the chloride penetration resistance while its resistance towards water absorption decreases. The preliminary investigation inferences that inclusion of CBA as replacement of PC and NFA improves the mechanical and durability aspects of concrete when used jointly. Hence, it is suitable to produce concrete as a combined replacement of PC and FNA in context to mechanical and durability aspects.

Keywords: concrete, coal bottom ash, durability, chloride permeability, capillary water absorption, compressive strength