What is it about?
Coal bottom ash is a major byproduct of coal-based power generation, but its direct use in construction is limited by its poor engineering properties. This study evaluates the potential of cement and ultrafine GGBS to improve the strength and durability of crushed coal bottom ash. The influence of binder content and curing period on strength development was assessed, along with resistance to repeated wetting–drying cycles. Microstructural characteristics were examined to explain how the binders modify particle bonding and the internal fabric of the treated material.
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Why is it important?
Cementitious treatment converts coal bottom ash from a low-value waste into a stronger and more stable material suitable for geotechnical applications. Ultra-fine GGBS produced greater strength and a denser microstructure, while cement-treated bottom ash showed better resistance to repeated wetting and drying, indicating that the binder can be selected to suit the governing field condition. The treated material can therefore be used in embankments, pavement subbases and structural fills, easing the burden of ash disposal and reducing demand for conventional construction materials. Using ultra-fine GGBS, itself an industrial byproduct, further reduces reliance on energy-intensive cement and supports lower-carbon construction.
Perspectives
This work shows how two industrial byproducts, coal bottom ash and ultra-fine GGBS, can be paired into a usable construction material rather than managed as waste. A key outcome is that the binder giving the highest strength does not necessarily give the best durability: Ultra-fine GGBS produced higher strength and greater microstructural densification, whereas cement performed better under repeated wetting and drying. Binder selection should therefore be governed by the expected field exposure and not by strength alone. Extending this work to field-scale trials, longer curing periods and other exposure conditions would help establish design guidance for the routine use of treated bottom ash in geotechnical construction.
L Abhijith
National Institute of Technology Calicut
Read the Original
This page is a summary of: Effects of Cementitious Binders on Mechanical and Microstructural Characteristics of Coal Bottom Ash, Journal of Testing and Evaluation, April 2026, ASTM International,
DOI: 10.1520/jte20250190.
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