Comparative analysis of corrosion resistance and purification performance of geopolymer recycled pervious concrete under acid rain soaking and spraying simulation

Acid rain corrosion is a critical factor contributing to the increased susceptibility of concrete pavements to cracking and reduced service life, raising significant safety concerns. This research aims to investigate the acid rain corrosion resistance and purification performance of geopolymer recycled pervious concrete (GRPC) with top-bottom interconnected channels under acid rain soaking and spraying simulation tests. The impacts of acid rain exposure on the compressive strength, permeability coefficient, mass loss, neutralization depth of GRPC, and the pH value of percolating acid rainwater were analyzed. The results proved that GRPC exhibited excellent resistance to simulated acid rain with a pH of 4.0. Furthermore, employing a combination of sodium hydroxide and sodium silicate as alkali-activators provided the optimal acid rain corrosion resistance. Additionally, in the early stage of acid rain exposure, acid rain was neutralized by the sodium carbonate formed through efflorescence. While in the middle-later stage, the migrating alkaline substances in GRPC matrix directly neutralized the pH of acid rain. Notably, after 28 days of simulated acid rain spraying, GRPC maintained its ability to purify the acid rain flowing through its channels, successfully raising the pH from 4 to a range between 7 and 8, demonstrating an effective acid rain purification capability. In conclusion, GRPC can transform the efflorescence issue in concrete into an effective means to counteract acid rain corrosion, thereby equipping concrete pavements with the dual advantages of alleviating urban waterlogging and resisting acid rain corrosion. This renders GRPC a promising avenue for both academic research and practical engineering applications.