Solidification of Loess Using a Composite Geopolymer Based on Slag Powder and Fly Ash: Influencing Factors and Mechanism Analysis
Publication: Journal of Materials in Civil Engineering
Volume 36, Issue 12
Abstract
To solve the problem of carbon emissions and pollution of traditional cement, composite geopolymer based on alkali-stimulated slag powder and fly ash was used to solidify loess. The effects of the alkali activator content, the ratio of NaOH to alkali activator, and the ratio of slag powder to silicon-aluminum (Si-Al) raw material on the unconfined compressive strength (UCS) of solidified loess were investigated through different tests. Then, the results from microscopic tests such as scanning electron microscopy (SEM), x-ray diffraction (XRD), and mercury intrusion porosimetry (MIP), as well as the variation results of the UCS, were used to analyze the influencing mechanism of the three factors on the solidified loess. The test results showed that the UCS of the slag powder– and fly ash–based composite geopolymer solidified loess first increased and then decreased with the increasing alkali activator content, and the UCS of the solidified loess also first increased and then decreased with the ratio of NaOH to alkali activator. The UCS increased as the ratio of slag powder to Si-Al raw material increased. The reaction of composite geopolymer solidified loess produces amorphous hydrated calcium silicate hydrates (C─ S─ H), calcium aluminum silicate hydrates (C─ A─ S─ H), and sodium-based aluminosilicate (N─ A─ S─ H) gels. These gels effectively bond and fill the soil particles, leading to a decrease in the number of macropores and total pores in the soil. As a result, the soil becomes more compact and increases the UCS of solidified loess. The results of this study provide a certain basis for engineering applications of the composite geopolymer to solidify loess based on slag powder and fly ash.
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Data Availability Statement
Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.
Acknowledgments
This work was supported by Chongqing Talent Innovation and Entrepreneurship Demonstration Team Project (No. cstc2024ycjh-bgzxm0012), Scientific Research Project of Shanghai Municipal Engineering Design Institute (Group) Co. Ltd., (K2023K124A), and the Fundamental Research Funds for the Central Universities (No. 2023CDJKYJH105).
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Information & Authors
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Published In
Journal of Materials in Civil Engineering
Volume 36 • Issue 12 • December 2024
Copyright
© 2024 American Society of Civil Engineers.
History
Received: Dec 15, 2023
Accepted: May 9, 2024
Published online: Oct 3, 2024
Published in print: Dec 1, 2024
Discussion open until: Mar 3, 2025
ASCE Technical Topics:
- Ashes
- Bodies of water (by type)
- Coasts, oceans, ports, and waterways engineering
- Composite materials
- Engineering materials (by type)
- Environmental engineering
- Fly ash
- Hydraulic engineering
- Hydraulic structures
- Loess
- Materials engineering
- Polymer
- River engineering
- Sediment
- Slag
- Solidification
- Structural engineering
- Structures (by type)
- Synthetic materials
- Waste management
- Waste treatment
- Water and water resources
- Water management
- Waterways
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