Journal article
Engineering properties and pore structure of lightweight aggregates produced from off-spec fly ash
Construction & building materials, v 348
19 Sep 2022
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
•High- and low-calcium off-spec fly ash based lightweight aggregate (LWA) was produced.•Engineering properties and pore structure of LWA was characterized.•Small dose of NaOH as fluxing agent can result in off-spec fly ash based LWA with desired engineering properties.
This study characterizes the engineering properties of lightweight aggregate (LWA) manufactured from low calcium (F-FA) and high calcium (C-FA) waste fly ash that were designed using a previously-developed thermodynamics-guided process. LWA properties that were characterized include specific gravity, vacuum water absorption, water absorption over time, water desorption, porosity, pore size distribution, and permeability. The LWA studied had a low oven dry specific gravity ranging from 1.22 to 1.45. The vacuum absorption and total open porosity of F-FA LWA decreased as the fluxing agent (NaOH) concentration increased while the values for C-FA LWA varied with increasing amounts of fluxing agent. All LWA passed the ASTM C1761 water absorption/desorption requirements for application to the internal curing of concrete. X-ray computed tomography (XCT) and dynamic vapor sorption analyzer (DVSA) techniques were used to characterize the LWA pore structure. It was found that for F-FA LWA the normalized porosity, counting only pores smaller than 50 nm (gelpores + mesopores), ranged from 4 % to 11.5 %, while for C-FA LWA, this same pore size range had porosity ranging from 1.7 % to 2.8 %. Pore size distribution measurements of F-FA LWA using XCT showed that the pores became larger and the predicted permeability coefficient increased as the fluxing agent concentration increased. For C-FA LWA, the predicted permeability increased with increasing NaOH concentration. Since the pore size distribution had greater variability and did not follow a specific increasing trend, the increase in C-FA permeability could only be due to an increase in pore connectivity.
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Details
- Title
- Engineering properties and pore structure of lightweight aggregates produced from off-spec fly ash
- Creators
- Mohammad Balapour - Drexel UniversityThiha Thway - Drexel University, Department of Chemical Engineering, 3141 Chestnut Street, Philadelphia, PA 19104, USANewell Moser - National Institute of Standards and Technology, Applied Chemicals and Materials Division, 325 Broadway, Boulder, CO 80305, USAEdward J. Garboczi - National Institute of Standards and Technology, Applied Chemicals and Materials Division, 325 Broadway, Boulder, CO 80305, USAY. Grace Hsuan - Drexel University, Department of Civil, Architectural and Environmental Engineering, 3141 Chestnut Street, Philadelphia, PA 19104, USAYaghoob Farnam - Drexel University
- Publication Details
- Construction & building materials, v 348
- Publisher
- Elsevier
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Civil, Architectural, and Environmental Engineering
- Web of Science ID
- WOS:000861379400001
- Scopus ID
- 2-s2.0-85135540446
- Other Identifier
- 991019173628404721
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InCites Highlights
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Construction & Building Technology
- Engineering, Civil
- Materials Science, Multidisciplinary