Recycling bottom ash in cement-stabilized pavement materials: Mechanical performance and environmental feasibility

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Publication Details

Author list: Thanasisathit N.; Lhajai S.; Jongpradist P.; Jamsawang P.

Publisher: Elsevier

Publication year: 2025

Volume number: 22

ISSN: 2214-5095

URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-105007717337&doi=10.1016%2fj.cscm.2025.e04892&partnerID=40&md5=8d2b1c9957a46e5d82f26a9437f095bd

Languages: English-Great Britain (EN-GB)

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Abstract

This study investigates the feasibility of utilizing bottom ash (BTA), a by-product of coal combustion, as a sustainable partial replacement for sand in cement-stabilized mixtures for pavement applications. Cement-stabilized mixtures incorporating BTA (0–50 %) and cement (1–7 %) were evaluated for their mechanical and durability performance through unconfined compressive strength, splitting tensile strength, California bearing ratio, and wetting-drying resistance tests. Microstructural analyses, including X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectrometry, were conducted to elucidate hydration mechanisms and structural transformations governing strength development. A predictive model for unconfined compressive strength was established, demonstrating a strong correlation (R² = 0.8364) with curing time, cement, and BTA content. The optimal mix, comprising 20 % BTA and 7 % cement, achieved a 6.6 MPa unconfined compressive strength at 120 days, significantly outperforming the control sample (3.2 MPa). California bearing ratio tests yielded a peak value of 727 %, indicating superior load-bearing capacity. Environmental assessment confirmed that heavy metal leaching from BTA-cement-stabilized mixtures remained within regulatory safety limits. The findings demonstrate that stabilized mixtures meet or exceed the Department of Highways, Thailand standards for subbase and base layers, with 20 % BTA and 7 % cement suitable for soil-cement base applications and 30 % BTA with 3 % cement viable for subbase layers. This study highlights the potential of BTA as a cost-effective, sustainable alternative in pavement construction, promoting resource efficiency and circular economy principles in the construction sector. © 2025 The Authors

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