Mechanical Performance and Chloride Penetration of Calcium Sulfoaluminate Concrete in Marine Tidal Zone

• Published in: Materials Vol. 16; no. 7; p. 2905
• Main Authors: Tang, Xudong, Zhan, Shulin, Xu, Qiang, He, Kui
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 06.04.2023; MDPI
• Subjects: Aggregates; Alkalinity; Aluminum; Aluminum hydroxide; Calcium ions; calcium sulfoaluminate cement; Cement; Chloride; chloride penetration; Chlorides; Chlorine; Compressive strength; Concrete properties; Corrosion; Curing; Decomposition reactions; Drying; drying–wetting cycles; Energy consumption; Epoxy resins; Ettringite; Hydrates; Hydration; Marine environment; marine tidal environment; Mechanical properties; Penetration; Permeability; Porosity; Portland cements; Sea-water; Seawater; Sulfoaluminate cement; Wetting; China; United States > US; chloride penetration; calcium sulfoaluminate cement; drying–wetting cycles; marine tidal environment
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma16072905

The enhancement of the durability of sulfoaluminate cement (CSA) in marine environments is of great importance. To this end, an investigation was carried out involving the placement of CSA concrete in the tidal zone of Zhairuoshan Island, Zhoushan, China, and subjected to a 20-month marine tidal exposure test. The comparison was made with ordinary Portland cement (OPC) concrete to evaluate the effectiveness of the former. The test findings indicate that the compressive strength of both types of concrete is reduced by seawater dry-wet cycling, and the porosity of the surface concrete is increased. However, the compressive strength of CSA concrete is observed to be more stable under long-term drying-wetting cycles. When the ettringite in the CSA surface concrete is decomposed due to carbonization and alkalinity reduction, its products will react with Ca and SO in seawater to regenerate ettringite to fill in the concrete pores, making the concrete strength more stable and hindering chlorine penetration. Furthermore, CSA concrete exhibits a higher capillary absorption capacity than OPC concrete, which results in chloride accumulation on its surface. However, the diffusion capacity of chloride in CSA concrete is significantly lower than that in OPC concrete.