Microstructure evolution and damage mechanisms of concrete-rock-composite corrosion in acid environment

Abstract

The acidic groundwater poses a significant threat to the durability of engineering structures, primarily due to the combined effects of acid erosion. As an important material used in concrete engineering, the application of concrete-rock composite (CRC) under acid erosion and preloading conditions plays a crucial role in determining the service life of the engineering project. The present study investigates the specific impact of acid and preloading environment on CRC. This is achieved by measuring the mass loss, pH variation, changes in microstructure, and degradation of mechanical parameters. The results show that the pH in different solutions increases with the increase in soaking time, and the mass loss is greater with the decrease in pH in chemical solutions. The mass loss of the soaked CRC in the pH1, pH3, pH5, and pH7 solutions was 8.02 g, 5.98 g, 5.19 g and 2.72 g, respectively. Nuclear magnetic resonance (NMR) T2 spectra area and porosity of CRC increase with the increase in acidity of the chemical solution and immersion time. Moreover, the peak strength and elastic modulus of the CRC samples decrease after being treated with the acid solution and subjected to preloading. The mechanism of deterioration damage is analyzed, and a chemical damage model is established to predict the strength of CRC samples under various acid solutions. Therefore, the research can effectively evaluate the durability and operational lifespan of engineering structures in acidic solutions. This has significant reference value for engineering design, construction, monitoring and reinforcement.