Case Study of Ultra-High-Performance Concrete with Urban Sludge Gasification Slag

Juntao Ma (), Yanbo Huang, Zhiyong Li, Manman Yang, Yunfei Tan and Shunbo Zhao
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Juntao Ma: International Joint Research Lab for Eco-Building Materials and Engineering of Henan, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
Yanbo Huang: International Joint Research Lab for Eco-Building Materials and Engineering of Henan, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
Zhiyong Li: Zhengzhou Sewage Purification Co., Ltd., Zhengzhou 450045, China
Manman Yang: Xuchang Innovation Center of Low-Carbon Eco-Building Materials Technology, Zhongyuan Institute of Science and Technology, Zhengzhou 450042, China
Yunfei Tan: Zhengzhou Sewage Purification Co., Ltd., Zhengzhou 450045, China
Shunbo Zhao: International Joint Research Lab for Eco-Building Materials and Engineering of Henan, North China University of Water Resources and Electric Power, Zhengzhou 450045, China

Sustainability, 2025, vol. 17, issue 3, 1-17

Abstract: This article, for the first time, investigates the potential of Sludge Gasification Slag (SGS), a byproduct of urban sewage sludge gasification, as a lightweight aggregate in ultra-high-performance concrete (UHPC), proposing a novel sustainable solution for the utilization of SGS. The UHPC mix design followed the modified Andreasen and Andersen model, incorporating pretreated SGS, cement, silica fume (SF), river sand, and a high-efficiency water-reducing agent. A total of eight experimental groups were developed, including five pre-wetted groups (I1–I5) and three dry groups (N1–N3), to evaluate the rheological and mechanical properties of UHPC. For the first time, this study combines scanning electron microscopy (SEM) and nitrogen adsorption techniques to investigate the interfacial transition zone (ITZ) and porosity of SGS-UHPC, providing insights into the influence of SGS on the matrix. The results show that SGS, due to its irregular particle shape and high water absorption capacity, negatively impacts the flowability of the fresh mix. However, when the SGS content reached 7.5%, the plastic viscosity of the UHPC mix peaked. Notably, after 28 days of curing, the compressive strength of the 5% pre-wetted SGS group exceeded that of the control group by 5%, indicating a time-dependent strength improvement. This enhancement is primarily attributed to the water release effect of SGS, which optimizes the ITZ and strengthens the overall matrix. The findings suggest that SGS, when used at dosages below 7.5%, can be effectively incorporated into UHPC, offering a promising, environmentally friendly alternative for sustainable construction applications.

Keywords: ultra-high-performance concrete; sludge gasification slag; rheological properties; mechanical properties; microstructure; thresholding (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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