Stability assessment of masonry pagodas based on multi-temporal survey and material analysis

This study evaluates the condition and conservation effects of three Tang Dynasty masonry pagodas at Foguang Temple, Shanxi, through multi-temporal 3D laser scanning, material analysis, and micro-environmental monitoring. Four surveys (2011, 2020, 2024, and 2025) documented the pre-conservation, construction, and post-conservation stages. Two pagodas show inclinations of about 2° and 3°, but no significant increase over time. Major active risks include surface deterioration, mortar loss, vegetation growth, moisture ingress, and salt-related decay. Material tests show that exposed bricks have higher water absorption and more advanced deterioration than inner layers, while environmental data reveal strong seasonal temperature-humidity fluctuations and winter low temperatures. Based on this diagnosis, conservation focused on drainage improvement, waterproofing, vegetation removal, local repair, repointing, and compatible materials rather than large-scale structural correction. The results support diagnosis-driven minimum intervention and a traceable framework for preventive conservation.