Investigation on Engineering Characteristics of Lime-Stabilized Phosphogypsum Subgrade Filler
Publication: Journal of Materials in Civil Engineering
Volume 36, Issue 4
Abstract
Phosphogypsum, which contains toxic components (e.g., heavy metal elements and fluoride), is one of the byproducts of phosphoric acid production, and filling subgrade is one of the recycling methods for it. In this study, phosphogypsum was stabilized by lime to improve the mechanical properties [California bearing ratio (CBR), resilience modulus, unconfined compressive strength, and shear strength], water stability, and harmful substances dissolubility. Combined with scanning electron microscopy, the strength formation and water stability enhancement mechanism of lime-stabilized phosphogypsum (LSP) were explored. The results demonstrated that the mechanical properties of LSP were better with the lime content of 6%–10%. The CBR, resilience modulus, unconfined compressive strength, and shear strength were 3.35 times, 2.46 times, 8.61 times, and 1.39 times that of plain phosphogypsum, respectively. An intensity prediction model with a correlation of 97% was constructed. The CBR and resilience modulus softening coefficient of LSP reached best values when lime content was 6%–8%. The leaching concentration of arsenic, chromium, and lead of LSP with 2% lime met the quality standards of groundwater levels I, II, and IV, respectively. Fluoride and phosphate were not detected in LSP when lime content was greater than 6.0%. The results show that LSP is feasible as subgrade filler. Considering the mechanical properties, water stability, and dissolution of hazardous substances of LSP, it is recommended to add 6%–8% lime content to LSP as highway subgrade filler.
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Data Availability Statement
Some or all data, models, or codes that support the results of this study are available from the corresponding author upon reasonable request.
Acknowledgments
This work was supported by the Key R&D plan of Shaanxi Province [number 2023-YBSF-390], Innovation Capability Support Program of Shaanxi [number 2022TD-07], and Fundamental Research Funds for the Central Universities of CHD [number 300102212906].
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Published In
Journal of Materials in Civil Engineering
Volume 36 • Issue 4 • April 2024
Copyright
© 2024 American Society of Civil Engineers.
History
Received: Mar 13, 2023
Accepted: Sep 14, 2023
Published online: Jan 24, 2024
Published in print: Apr 1, 2024
Discussion open until: Jun 24, 2024
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