Journal article
Scale-up framework to manufacture waste coal ash based lightweight aggregate
Journal of Building Engineering, v 115, 114429
Dec 2025
Abstract
This study presents a structured framework for producing lightweight aggregate (LWA) from waste coal ash in landfills using a proprietary sintering technique. The work was conducted in two phases: In Phase I, a lab-scale approach was developed to optimize key manufacturing parameters such as fluxing and binding agent dosages, sintering temperature, and mean residence time (MRT), to achieve the desired engineering properties. In Phase II, half a ton of LWA was produced at a larger scale using two types of off-spec coal ash with high loss on ignition, which were unsuitable as supplementary cementitious materials. Leaching tests showed that sintered LWA had reduced potential for heavy metal release compared to raw coal ash. This was attributed to extended MRT and high sintering temperatures, which promoted slag formation and heavy metal entrapment. The optimized lab-scale parameters were successfully translated to large-scale production. In both cases, the LWA met ASTM standards, confirming their suitability for concrete applications. Engineering properties were consistent across scales, demonstrating scalability. Microstructural analysis revealed a core-shell morphology and confirmed the bloating mechanism—pore formation within the slag phase. Despite some large, disconnected voids, the formation of sufficient slag contributed to the desired crushing strength of the LWA. Overall, the study demonstrates a repeatable and scalable method for converting low-quality coal ash into valuable construction material through controlled sintering. It highlights the environmental and structural benefits of this approach, particularly in reducing the landfill burden and promoting safe reuse of industrial by-products.
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Details
- Title
- Scale-up framework to manufacture waste coal ash based lightweight aggregate
- Creators
- Mo Balapour (Corresponding Author)Robin DebYaghoob Amir Farnam
- Publication Details
- Journal of Building Engineering, v 115, 114429
- Publisher
- Elsevier
- Number of pages
- 20
- Grant note
- National Science Foundation: 2126564, 2321815
Funding sources This research was supported by the National Science Foundation under Award No. 2126564 and 2321815. The funding agency was not involved in the study design; collection, analysis, and interpretation of data; writing of the report; or the decision to submit the article for publication.
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Civil, Architectural, and Environmental Engineering
- Web of Science ID
- WOS:001614212600004
- Scopus ID
- 2-s2.0-105020856889
- Other Identifier
- 991022127752404721
InCites Highlights
Data related to this publication, from InCites Benchmarking & Analytics tool:
- Web of Science research areas
- Construction & Building Technology
- Engineering, Civil