Influences of high-volume coal bottom ash as cement and fine aggregate replacements on strength and heat evolution of eco-friendly high-strength concrete

Abstract

This study investigates the potential of using high-volume bottom ash as a supplementary cementitious material (SCM) and fine aggregate replacement in production of high-strength concrete. In the first stage, bottom ash quality was improved by sieving through a No. 50 sieve and grinding to increase fineness. Ground bottom ash (GBA) replaced ordinary Portland cement (OPC) at 35%, 50%, and 65% by weight to produce high-strength concrete. In the second stage, coarse bottom ash (CBA) retained by a No. 50 sieve replaced fine aggregate in an optimum mixture at 20%, 40%, and 60% by volume. Concrete properties including compressive strength, modulus of elasticity, autogenous shrinkage, and heat evolution were evaluated. The economic and environmental impacts of GBA were assessed. The results indicated that concrete with 50% GBA cement replacement could be classified as high-strength concrete at 7 d, achieving a compressive strength of approximately 80.9 MPa at 28 d. Autogenous shrinkage was decreased with an increase in GBA content. The heat evolution of concrete with 50% GBA was decreased by 36.4% compared with the control concrete. Concrete with 50% GBA cement replacement and 60% CBA fine aggregate replacement demonstrated the greatest reduction in autogenous shrinkage and peak of heat evolution, and it was classified as high-strength concrete.