Water Absorption Properties of Low-Temperature Fired Bricks for Restoration of Historical Brick Buildings in Thailand

In the restoration of cultural properties, the original materials and construction methods should be used in principle from the viewpoints of authenticity and anastylosis. Low-temperature fired bricks made by traditional methods are used for the restoration of historical brick buildings in Ayutthaya, Thailand. From the deterioration survey of the restorative bricks used in the 2013 restoration of Wat Krasai pagoda, the deterioration rate was significantly faster in parts where rainwater was collected. In addition, salt weathering was recognized. In order to ensure the long-term soundness of cultural property buildings after restoration based on the proper restoration method, it is necessary to understand the characteristics of restoration materials. Therefore, to evaluate the effect of salts and water content conditions on the deterioration of the restorative bricks, immersion experiments using distilled water were conducted as a preliminary experiment. 5 specimens (5 cm x 5 cm x 2 cm) were immersed in distilled water, and the surface dry mass was measured every 3 to 7 days. The distilled water was replaced at the time of measurement. The results showed that the surface dry mass increased cumulatively, and the deterioration such as cracking and chipping hardly progressed with distilled water even after 5000 hours.