Material heterogeneity and component-scale differential weathering in a granitic stone monument: the Wongongguksa Stupa, South Korea

The weathering of stone monuments is commonly interpreted in relation to environmental exposure, while assuming material uniformity. However, many heritage structures consist of components with differing material properties. This study investigates component-scale weathering variability in the Wongongguksa Stupa (South Korea), a granitic monument comprising original and replaced elements. Petrography, magnetic susceptibility, surface deterioration mapping, and ultrasonic pulse velocity (UPV) analyses were used to evaluate differences among structural components. Grain size and textural variations were reflected in the internal physical condition and in the spatial distribution of detachment-related features, including exfoliation, scaling, and material loss. These patterns were more consistently expressed at the component scale than by orientation. In contrast, surface discoloration was widely distributed and associated with carbon-rich deposits identified by scanning electron microscopy-energy dispersive spectroscopy, suggesting atmospheric influence. These observations indicate that weathering varies among structural components according to material properties, whereas surface disposition mainly reflects atmospheric inputs.