Lithological characteristics and homogeneity of alternative stone for restoration of the Hong Nang Sida temple in Vat Phou, Lao PDR

The Hong Nang Sida temple with significant historical value was designated as a UNESCO world cultural heritage. However, most parts of the main temple were destroyed, and being neglected for a long time. Some remained building structures also have been influenced on asymmetric load, it causes various types of damage including imbalance problem. Accordingly, reasonable conservation treatment and proper restoration processes are required. The stone material of the main temple in Hong Nang Sida is made with sandstone and siltstone, and by assuming that they were extracted from nearby Mt. Phou Kao. Specimens were collected from Mt. Phou Kao, Douangdy and Vat Chompet quarries to review the homogeneity with the stones in Hong Nang Sida temple. Also, by analyzing the sandstone used to restore the Vat Phou temples located around the Hong Nang Sida temple, it was examined whether it could be used for restoration of the Hong Nang Sida temple. The study on the homogeneity of stones revealed that it would be the most desirable to use rocks from Mt. Phou Kao as alternative stones for restoration of the main temple. It has different lithological and geochemical characteristics from the restoration stone of the Vat Phou temple. However, as Mt. Phou Kao was designated as world cultural heritage protection area, it is hard to get sufficient amount of alternative stones for restoration. Thus, it is proper to secure alternative stones from Douangdy and Vat Chompet quarries, considering the geochemical homogeneity, color and sedimentary structure as well as procurement possibility.