Long-term consolidation effect of polyurethane with multi-concentration on sandstone cultural heritage of the Confucian Temple in Pingxiang, Jiangxi Province

The Pingxiang Confucian Temple is a provincially protected cultural relic site in Jiangxi, China. Most of its stone components have long been exposed to open-air or semi-open-air conditions and suffer from severe weathering, including surface dissolution, powdering, and flaking, driven by high temperature–humidity and acid-rain corrosion. In this study, a polyurethane-based penetrating consolidant was applied to sandstone relics from the temple. Different volumetric proportions of deionized water were used to prepare consolidant formulations, and penetration-consolidation experiments were conducted under open-air and semi-open-air service conditions. The consolidant performance and structural evolution were systematically evaluated through long-term monitoring of morphological changes and continuous tracking of the mechanical properties of the stone substrate. The results provide methodological references and technical guidance for penetration-consolidation treatments of sandstone relics in Jiangxi Province.