『Abstract
　This article is based on field investigations carried out at Ta Keo and Banteay Srei temples (Angkor, Cambodia), which have similar environmental histories and display the same recurrent decorative pattern (lotus petal) in three different sandstone lithotypes. Based on two original scales of mechanical and chemical weathering, the degree of deterioration of c.2000 sandstone petals was visually assessed, resulting in the proposal of a durability scale. An explanatory scheme was provided, based on laboratory analyses of stone materials (ICP-AES, XRD, SEM-EDS, polarizing microscopy and mercury injection). The key drivers of sandstone durability are both mineralogical and petrophysical. The remarkable preservation of the pink sandstone is due to the quartzose nature of its clasts, the non-swelling clay content of its abundant matrix (kaolinite) and its porosity structure (large connected pores and probable non-connected porosity). The overall good preservation of the green sandstone is due to its extremely low porosity and specific surface area, associated with its strong cementation. The severe deterioration of the grey sandstone id due to its laminated structure (oriented biotites), the susceptibility to hygric swelling and solution of its binding agents (chlorite/smectite and calcite) and its porosity structure, which evolves during a two-stage weathering sequence. The first stage is characterized by a bimodal porosity due to the partial clogging of macropores by swelling clays, and the second stage by a substantial increase in porosity and the penetration of salts (barite and anhydrite). Conversely, oxidation phenomena associated with weathering can lead to a drastic reduction of porosity.

Keywords: Cambodia; Angkor temples; Chemical weathering; Mechanical weathering; Stone properties; Sandstone durability

Introduction
Investigated monuments and stone materials
　Ta Keo temple
　Banteay Srei temple
　Stone materials
Methods
　Field investigations and sampling
　　Visual assessment of sandstone decay
　　Standardized categorization of weathering intensities
　　Sampling conditions
　Laboratory analyses
　　ICP-AES
　　Polarizing microscopy
　　SEM-EDS
　　XRD
　　Petrophysical analyses
Results
　Visual assessment of sandstone decay
　Categorization of weathering intensities
　Laboratory analyses
　　ICP-AES analyses and polarizing microscopy
　　X-ray diffractometry
　　SEM
　　Petrophysical analyses
Interpretation and discussion
　Durability scale and key drivers
　　Pink sandstone: overall champion
　　Green sandstone: close to the best
　　Grey sandstone: definitely the worst
　Comparison with other building sandstones
Conclusion
Acknowledgments
References