Study on synergistic solidification method for municipal solid waste incineration fly ash: Core chemical stabilization and shell physical encapsulation

To address the challenges of low utilization rates, complex hazardous substances (such as heavy metals and dioxins), and safety concerns in the resource utilization of municipal solid waste incineration fly ash (MSWIFA), this study developed a core-shell structure by combining an alkali-activated MS...

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Main Authors: Feng Xing, Xingyun Zheng, Di Wu, Hui Zhong, Biqin Dong, Binmeng Chen, Guohao Fang
Format: Article
Language:English
Published: Elsevier 2025-07-01
Series:Case Studies in Construction Materials
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Online Access:http://www.sciencedirect.com/science/article/pii/S2214509525004498
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author Feng Xing
Xingyun Zheng
Di Wu
Hui Zhong
Biqin Dong
Binmeng Chen
Guohao Fang
author_facet Feng Xing
Xingyun Zheng
Di Wu
Hui Zhong
Biqin Dong
Binmeng Chen
Guohao Fang
author_sort Feng Xing
collection DOAJ
description To address the challenges of low utilization rates, complex hazardous substances (such as heavy metals and dioxins), and safety concerns in the resource utilization of municipal solid waste incineration fly ash (MSWIFA), this study developed a core-shell structure by combining an alkali-activated MSWIFA core with an ultra-high-performance concrete (UHPC) shell. This system establishes a synergistic solidification mechanism through the chemical immobilization and physical encapsulation. The results indicate that the alkali activation forms C-(A)-S-H and N-A-S-H gels, achieving chemical immobilization efficiencies of 89.4 %, 97.4 %, and 81.2 % for Zn, Cr, and Cu, respectively, while failing to fully immobilize Pb and Cd. Encapsulation with UHPC significantly reduced the leaching concentrations of heavy metals, with an inhibition effect on the leaching of heavy metals that can reach up to 99 %, with all elements meeting the prescribed limits. Furthermore, the dioxin content decreased substantially to 13 ng TEQ/kg, representing a 70 % reduction compared to the raw MSWIFA. Additionally, the encapsulated core-shell structure exhibited a single-particle strength of 4.17 MPa and a water absorption rate of only 0.19 %, demonstrating excellent mechanical properties and compactness. The optimized pore structure and dense interfacial transition zone (ITZ) further enhanced the environmental safety of the core-shell structure and its potential for use as an aggregate. This synergistic solidification technology effectively improves the performance and stability of MSWIFA-based aggregates, providing a promising solution for the resource utilization and pollution control of MSWIFA.
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spelling doaj-art-2f114506a62448b49a161fb17b8a36bb2025-08-20T02:26:27ZengElsevierCase Studies in Construction Materials2214-50952025-07-0122e0465110.1016/j.cscm.2025.e04651Study on synergistic solidification method for municipal solid waste incineration fly ash: Core chemical stabilization and shell physical encapsulationFeng Xing0Xingyun Zheng1Di Wu2Hui Zhong3Biqin Dong4Binmeng Chen5Guohao Fang6College of Civil and Transportation Engineering, Guangdong Province Key Laboratory of Durability for Marine Civil Engineering, Shenzhen Key Laboratory for Low-Carbon Construction Material and Technology, Shenzhen University, Shenzhen 518060, ChinaCollege of Civil and Transportation Engineering, Guangdong Province Key Laboratory of Durability for Marine Civil Engineering, Shenzhen Key Laboratory for Low-Carbon Construction Material and Technology, Shenzhen University, Shenzhen 518060, China; Institute for Carbon Neutrality, Shenzhen University, Shenzhen 518060, ChinaCollege of Civil and Transportation Engineering, Guangdong Province Key Laboratory of Durability for Marine Civil Engineering, Shenzhen Key Laboratory for Low-Carbon Construction Material and Technology, Shenzhen University, Shenzhen 518060, China; Institute for Carbon Neutrality, Shenzhen University, Shenzhen 518060, ChinaCollege of Civil and Transportation Engineering, Guangdong Province Key Laboratory of Durability for Marine Civil Engineering, Shenzhen Key Laboratory for Low-Carbon Construction Material and Technology, Shenzhen University, Shenzhen 518060, China; Institute for Carbon Neutrality, Shenzhen University, Shenzhen 518060, ChinaCollege of Civil and Transportation Engineering, Guangdong Province Key Laboratory of Durability for Marine Civil Engineering, Shenzhen Key Laboratory for Low-Carbon Construction Material and Technology, Shenzhen University, Shenzhen 518060, ChinaInstitute of Applied Physics and Materials Engineering, University of Macau, MacaoInstitute for Advanced Study, Shenzhen Key Laboratory for Low-Carbon Construction Material and Technology, Shenzhen University, Shenzhen 518060, China; Institute for Carbon Neutrality, Shenzhen University, Shenzhen 518060, China; Corresponding author at: Institute for Advanced Study, Shenzhen Key Laboratory for Low-Carbon Construction Material and Technology, Shenzhen University, Shenzhen 518060, China.To address the challenges of low utilization rates, complex hazardous substances (such as heavy metals and dioxins), and safety concerns in the resource utilization of municipal solid waste incineration fly ash (MSWIFA), this study developed a core-shell structure by combining an alkali-activated MSWIFA core with an ultra-high-performance concrete (UHPC) shell. This system establishes a synergistic solidification mechanism through the chemical immobilization and physical encapsulation. The results indicate that the alkali activation forms C-(A)-S-H and N-A-S-H gels, achieving chemical immobilization efficiencies of 89.4 %, 97.4 %, and 81.2 % for Zn, Cr, and Cu, respectively, while failing to fully immobilize Pb and Cd. Encapsulation with UHPC significantly reduced the leaching concentrations of heavy metals, with an inhibition effect on the leaching of heavy metals that can reach up to 99 %, with all elements meeting the prescribed limits. Furthermore, the dioxin content decreased substantially to 13 ng TEQ/kg, representing a 70 % reduction compared to the raw MSWIFA. Additionally, the encapsulated core-shell structure exhibited a single-particle strength of 4.17 MPa and a water absorption rate of only 0.19 %, demonstrating excellent mechanical properties and compactness. The optimized pore structure and dense interfacial transition zone (ITZ) further enhanced the environmental safety of the core-shell structure and its potential for use as an aggregate. This synergistic solidification technology effectively improves the performance and stability of MSWIFA-based aggregates, providing a promising solution for the resource utilization and pollution control of MSWIFA.http://www.sciencedirect.com/science/article/pii/S2214509525004498MSWIFACold-bondedSynergistic solidificationLeaching toxicityArtificial aggregate
spellingShingle Feng Xing
Xingyun Zheng
Di Wu
Hui Zhong
Biqin Dong
Binmeng Chen
Guohao Fang
Study on synergistic solidification method for municipal solid waste incineration fly ash: Core chemical stabilization and shell physical encapsulation
Case Studies in Construction Materials
MSWIFA
Cold-bonded
Synergistic solidification
Leaching toxicity
Artificial aggregate
title Study on synergistic solidification method for municipal solid waste incineration fly ash: Core chemical stabilization and shell physical encapsulation
title_full Study on synergistic solidification method for municipal solid waste incineration fly ash: Core chemical stabilization and shell physical encapsulation
title_fullStr Study on synergistic solidification method for municipal solid waste incineration fly ash: Core chemical stabilization and shell physical encapsulation
title_full_unstemmed Study on synergistic solidification method for municipal solid waste incineration fly ash: Core chemical stabilization and shell physical encapsulation
title_short Study on synergistic solidification method for municipal solid waste incineration fly ash: Core chemical stabilization and shell physical encapsulation
title_sort study on synergistic solidification method for municipal solid waste incineration fly ash core chemical stabilization and shell physical encapsulation
topic MSWIFA
Cold-bonded
Synergistic solidification
Leaching toxicity
Artificial aggregate
url http://www.sciencedirect.com/science/article/pii/S2214509525004498
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