Abstract
Hagia Sophia in Istanbul has been suffering from severe degradation of the outside and inside walls and the paintings on the inside wall surfaces mainly due to liquid water transport and salt crystallization. In order to elucidate the degradation mechanism and then propose a suitable method for preservation, we have conducted a long-term field survey of Hagia Sophia from 2010 until 2014 and numerical analyses of simultaneous heat and moisture transfer in the walls. It was found that high moisture content — primarily due to penetration and evaporation of rain water and partly due to consequent salt crystallization — generally leads to degradation of both inside and outside walls. It was observed that the moisture content of the north inside wall is higher than that of the south inside wall due to less solar radiation. Also, there are high possibilities that evaporation mainly at the middle-layer mortar caused salt crystallization and exfoliation of the inside stucco wall surfaces and that the exfoliation of the inside finishing material of the wall caused further subsequent exfoliation of the inner layers.
