Effect of environmental conditions on the volume deformation of cement mortars with sewage sludge ash. (15th April 2023)

• Record Type: Journal Article
• Authors: Gu, Chunping; Shuang, Yuzhu; Ji, Yongjie; Wei, Haixia; Yang, Yang; Xu, Yanwen; Qian, Rusheng; Cui, Dong; Zhou, Hangjie
• Is Part Of: Journal of building engineering. Volume 65(2023)
• Publication Date: 2023-04-15
• Subjects: Sewage sludge ash -- Volume deformation -- Environmental condition -- Microstructure; Building -- Periodicals; 690.05
• DOI: 10.1016/j.jobe.2022.105720
• Languages: English
• ISSNs: 2352-7102

Abstract

Abstract: Sewage sludge ash (SSA) is obtained from wastewater sludge incineration, and it can be recycled in cement-based materials. The environmental conditions show significant influence on the volume deformation of cement-based materials with SSA. So in this study, the effect of environmental conditions on the volume deformation of mortars with SSA was investigated, and the underlying mechanism was preliminarily studied with isothermal calorimetry, X-ray diffraction (XRD) and thermogravimetry (TG). The results indicated that, under seal condition, SSA caused obvious expansion after the rapid shrinkage at very early age, and reduced the 28d autogenous shrinkage of mortars. Under drying condition, the addition of SSA enlarged the drying shrinkage of mortars. Under water immersed condition, the mortars expanded before the age of 7d, and more SSA led to more obvious expansion. The addition of SSA resulted in more ettringite formed in mortars under sealed and water immersed conditions, leading to the expansion of mortars. The findings of this study could help to control the volume deformation of mortars with SSA. Highlights: SSA with high SO3 contents was used to replace partial cement in mortars. Environmental conditions significantly affect volume deformation of mortars with SSA. Mortars with SSA showed expansion under sealed and water immersed conditions. The formation of ettringite was reason for the expansion of mortars with SSA.