Utilization of sieved and ground coal bottom ash powders as a coarse binder in high-strength mortar to improve workability

• Decreasing size of bottom ash may promote their utilization in cement composites.
• Bottom ash powders could improve in workability of high-strength mortar.
• Bottom ash powders improve hydration of mortar at early-age compared to fly ash.

In the present study, sieved and ground coal bottom ash powders were utilized in high-strength mortar as a coarse binder to help improve workability. The chemical and physical characteristics of the powders were evaluated. The hydration heat of blended binders was measured. The workability, hydration kinetics, compressive strength, and autogenous shrinkage of the mortar were investigated. The workability of the high-strength paste and mortar mixtures with bottom ash powders was significantly higher than that of mixtures including only cement and fly ash. Owing to their higher pozzolanic reactivity, the mortar containing bottom ash powders exhibited a higher degree of hydration and similar compressive strengths at 3 and 28 days compared to the mortar with fly ash.