Influence of weathering on the physicomechanical properties of sandstone: Multi-scale analysis

Sandstone is widely used in heritage architecture and engineering, yet its long-term durability is strongly influenced by weathering. Understanding how weathering-induced alterations propagate across multi-scale is essential for predicting sandstone durability. In this study, three sandstone samples with different degrees of weathering were collected. Microscale rock mechanics experiments were conducted to characterize mineral composition, microstructure, and mineral mechanical properties. These microscale observations were then integrated into accurate grain-based model (AGBM) to quantify the effects of weathering on macroscale Young’s modulus and P-wave velocity. Weathering selectively dissolves feldspar and calcite, promotes development of the micropores and microcracks, and causes mineral softening, leading to pronounced reductions in macroscale Young’s modulus (from 40.9 GPa to 14.1 GPa) and P-wave velocity (from 5.05 km/s to 2.81 km/s), while quartz and garnet remain relatively stable. This study develops a new method to explicitly link mineralogical alteration, microstructural damage, and mineral mechanical degradation to macroscale elastic properties and P-wave velocity. The proposed approach provides new mechanistic insights into the long-term behaviors of weathered sandstone and has important implications for heritage conservation, slope stability assessment, and seismic imaging in weathered rocks.