Journal article
A thermodynamics-guided framework to design lightweight aggregate from waste coal combustion fly ash
Resources, conservation and recycling, v 178, 106050
Mar 2022
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
A systematic thermodynamics-based framework was applied to recycle waste low and high-calcium coal combustion Fly Ash (FA) into synthetic lightweight aggregates (LWA) through sintering. The process to successfully manufacture synthetic LWA was investigated, which requires a delicate balance among three phenomena: (i) sufficient liquid phase formation during sintering, (ii) appropriate viscosity for the liquid-solid phase, and (iii) sufficient amount of gas emission to form pores in the LWA. Thermodynamics modeling was used to quantify the formation of the liquid phase during sintering while the fluxing agent and the temperature change. The Urbain- Kalmanovitch, Browning, and Krieger-Dougherty models were used to quantify the viscosity of the liquid and liquid-solid phase, respectively. A lower bound of 100 Pa•s for the viscosity was found to ensure spherical shape of the LWA. Using thermogravimetric analysis, it was shown that the LWA had a notable gas release potential, owing to the presence of anhydrite and hematite, which could create gas-filled pores in the LWA macro-microstructure. X-ray computed tomography (X-CT) observation revealed the formation of a porous structure for the produced LWA where high calcium FA LWA generally had larger pores compared with low calcium FA LWA. By correlating the X-CT and scanning electron microscopy (SEM) observations and thermodynamic modeling results, it was found that a minimum of 40% liquid phase content (% by mass) is necessary for the formation of gas-filled pores in FA-LWA.
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Details
- Title
- A thermodynamics-guided framework to design lightweight aggregate from waste coal combustion fly ash
- Creators
- Mohammad Balapour - Drexel UniversityThiha Thway - Drexel UniversityRathin Rao - Drexel UniversityNewell Moser - National Institute of Standards and TechnologyEdward J. Garboczi - National Institute of Standards and TechnologyY Grace Hsuan - Drexel UniversityYaghoob Farnam - Drexel University
- Publication Details
- Resources, conservation and recycling, v 178, 106050
- Publisher
- Elsevier
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Civil, Architectural, and Environmental Engineering
- Web of Science ID
- WOS:000767507800006
- Scopus ID
- 2-s2.0-85119133210
- Other Identifier
- 991019167557604721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Engineering, Environmental
- Environmental Sciences