Effect of sulfuric acid corrosion on the shear behavior of recycled coarse aggregate concrete-soil interfaces: An experimental study

This study investigates the shear behavior of recycled coarse aggregate concrete–soil interfaces subjected to sulfuric acid corrosion, with the aim of facilitating the practical application of recycled coarse aggregate concrete piles in chemically aggressive environments. Large-scale direct shear tests were conducted to examine the effects of corrosion time and recycled coarse aggregate replacement ratio on the interfacial shear strength and the corresponding shear displacement. The applicability of the conventional hyperbolic model for characterizing the shear stress–displacement relationship was evaluated, and a time-dependent modification was proposed to more accurately reflect the shear behavior of corroded interfaces. The test results show that both interfacial shear strength and displacement increase significantly with prolonged corrosion exposure, rising by 12% and 225%, respectively, after 90 days of sulfuric acid attack. Additionally, an increase in the recycled coarse aggregate replacement ratio enhances shear strength and displacement. Increasing the replacement ratio from 0% to 100% enhanced shear strength by 12.6% and displacement by 44.4%. While the classical hyperbolic model effectively described the shear stress–displacement relationship, the proposed time-dependent model eliminated reliance on experimental inputs and improved predictive accuracy under prolonged corrosion. These findings offer valuable guidance for the design and durability assessment of recycled coarse aggregate concrete pile foundations in acidic soil environments.