The effect of rock strength on weathering rates of sandstone used for Angkor temples in Cambodia

• Weathering rates of sandstone blocks used in the Angkor temples are documented.
• The weathering rate under tropics has a range of 7–92 mm ka− 1.
• The equation that estimates the hollow depth due to weathering is proposed.
• Temple age and the coefficient obtained from rock hardness explain the hollow depth.
• The coefficient is an effective index to explain weathering of historical structures.

This study determined the weathering rates from the depths of hollows formed by the deterioration of sandstone blocks used to build Angkor temples in the 7th–12th centuries. Due to capillary processes, these hollows generally develop at the bases of building components such as doorframes, false doorframes, window frames, and pillars. In this study, 55 locations in 29 temples were selected to measure maximum hollow depth. Based on the ages of the temples, the weathering rate was calculated to be in the range 7–92 mm ka− 1. The weathering rate was found to be independent of building component type and aspect. The calculated weathering rate corresponds to the physical weathering rate of sandstone caused by the wetting-drying cycles that result from the tropical environment along with the dry season. An equation that can estimate the maximum depth of a hollow in a sandstone block was proposed based on temple age and the coefficient obtained from two types of rock hardness values. The equation coefficient is an effective index that can help predict the deterioration of stone cultural artifacts such as the Angkor temples.