2025-12-21 INTERNATIONAL JOURNAL OF ARCHITECTURAL HERITAGE 2025 null(卷), null(期), (null页)
This study investigates the weathering mechanisms of sandstone components at the Yungang Grottoes, a UNESCO World Heritage site located in a semi-arid region of China. Using X-ray diffraction (XRD), scanning electron microscopy (SEM), and ion chromatography, a coupled deterioration process was identified, involving the hydration-induced structural adjustment of clay minerals, primarily illite, and the crystallization pressure from sulfate salts, such as gypsum and magnesium sulfate. The presence of illite-rich siltstone nodules, along with heterogeneity in the pore structure, facilitates the accumulation of salt and the propagation of microcracks. These factors result in the formation of cavities and the degradation of material. The results demonstrate the critical role of moisture-mineral interactions and salt crystallization in accelerating the weathering of sandstone, highlighting the synergistic interaction between clay-related microstructural weakening, salt crystallization, and the deterioration of pore structure. These findings provide a scientific basis for diagnosing weathering risks in sandstone heritage and inform conservation strategies for safeguarding historic structures in similar environmental conditions.