Enhancing Durability of Concrete in Saline Soil with Nano-CaCO3 Modification: Investigation and Reliability Analysis

In this study, the effect of nano-CaCO3 on the durability of concrete was investigated by simulating the attack of semi-buried concrete structures in saline soil. Different nano-CaCO3 contents were used to enhance the durability of concrete. The durability of different areas of nano-CaCO3 modified concrete, partially exposed to sulfate solution, was evaluated, and a reliability analysis was conducted. The results indicated that appropriate nano-CaCO3 content can improve the durability of concrete. In this study, concrete with a nano-CaCO3 content of 1% exhibited the highest durability. The corrosion degrees of different areas of the nano-CaCO3 modified concrete partially exposed to the sulfate solution decreased in the following order: dry-wet transition areas (M area) > fully immersed areas (D area) > exposed air areas (T area). A sulfate chemical attack occurred inside the concrete in the dry-wet transition areas, while a sulfate physical attack occurred on the surface concrete. The predicted values of the model agreed well with the test results. The bivariate Wiener process can effectively describe the whole process of performance deterioration of nano-CaCO3 modified concrete.