Journal of Emerging Trends in Engineering and Applied Sciences: Research Areas

Article Title: Assessing the Durability of Coal Bottom Ash as Aggregate Replacement in Low Strength Concrete
by Abdus Salaam Cadersa, Jaylina Rana and Toolseeram Ramjeawon

Abstract:
This paper assesses the use of coal bottom ash as coarse aggregate replacement in a grade 15 concrete, in an attempt to contribute to a sound management of coal ash on the island of Mauritius. It specifically investigates the effect of the bottom ash on the compressive strength, workability, water absorption and resistance to sulphate attack of the concrete. The coal bottom ash was obtained from a local thermal power plant. Experiments were conducted by replacing the coarse aggregate of 6/10 mm fraction by bottom ash by weight of coarse aggregate in varying percentages (25%, 50%, 75% and 100% respectively). The results showed that bottom ash causes a decrease in compressive strength, workability and durability. The latter effects are worsened with increasing bottom ash content such that the mixes with 75% and 100% aggregate replacement by bottom ash had poor workability and compressive strengths lower that the characteristic strength. Moreover, above 25% replacement, durability is compromised. The research concludes that only the coal bottom ash concrete with 25% replacement meets strength, workability and durability requirements. Adequate protection in the form of rendering/plastering should also be provided and exposure conditions must be limited to moderate environment only. Thus, partial replacement of coarse aggregates with 25% of coal bottom ash can potentially be used in low strength concrete applications, thereby contributing to the sustainable waste management targets of Mauritius.

Keywords: coal bottom ash, coarse aggregate replacement, grade 15 concrete, durability, sulphate resistance

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