Degradation of cast-in-situ concrete subjected to sulphate-chloride combined attack. (30th April 2020)

• Record Type: Journal Article
• Authors: Zhao, Gaowen; Li, Jingpei; Shi, Mei; Cui, Jifei; Xie, Feng
• Is Part Of: Construction & building materials. Volume 241(2020)
• Publication Date: 2020-04-30
• Subjects: Cast-in-situ concrete -- Degradation mechanisms -- Sulfate-chloride combined attack -- Sulfate diffusion; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2019.117995
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Chlorides negatively affect the strength development of concrete in the early stage. Chlorides accelerate the sulfate induced degradation in the later corrosion stage. Chlorides increase the diffusion speed of sulfates in the cast-in-situ concrete. Degradation behavior at the early stage controls the later degradation process. Abstract: The main aim of the present research is to determine the degradation mechanisms of cast-in-situ concrete subjected to sulphate-chloride combined attack. Concrete specimens were prepared and then put into sulfate or sulfate-chloride mixed solutions. The sample dimension, mass, compressive strength, and sulfate concentration of the specimens were continuously monitored. The microstructures and the complex mineral composition of the concrete were analysed after 12 months of exposure to the corrosive environments. The results show that cast-in-situ concrete suffers more severe damage and greater strength loss when subjected to sulfate-chloride combined attack than when subjected to sulfate only. The diffusion and accumulation of sulfates are accelerated by the coexisting chlorides, especially in the early stages. The coexistence of chlorides in sulfate environments accelerates the degradation of cast-in-situ concrete induced by sulfate attack. The different performances against sulfate-chloride combined attack between cast-in-situ and precast concrete were mainly due to the degradation behaviour at the early stage.