In this study, we focused on the material flow due to diffusion in the pore scale. Kyushu Research Institute for Cultural Properties Inc. and Kumamoto University have been introduced a new method, Aquo-Siloxane Method, in order to protect the stone heritages. By applying this method, it is expected that the material movement due to the diffusion is prevented. Here, one-dimensional diffusion tests were performed towards porous rock samples before and after applying Aquo-Siloxane Method, and the diffusion phenomena was visualized and analyzed by μ-focus X-ray CT. It was found that diffusion of solute is strongly prevented in the case of Kimashi sandstone by applying Aquo-Siloxane Method. In the case of Berea sandstone, diffusion phenomena were observed, however, it was found that the amount of diffused solute was much smaller than the sample before applying Aquo-Siloxane Method.
Stone heritages, such as stone architectures, stone statues, graveposts and stone towers, are generally located outside. Since they are generally exposed to the wind and rain, they have been defaced and collapsed due to weathering. Weathering is caused by many different reasons. In the cold district, freezing and thawing gives strong impacts to the rock structures (Carmona-Quiroga 2015). On the other hand, biodeterioration is also one of the most serious factors in the warm district (Schiavon 2013). However, in many cases, existence of water in rock structure is thought to be the main reason of weathering. Here, it is also known that not only the water but the solute which is involved in the water gives serious damages. The appropriate assessment of weathering due to the water and solute flow is important to preserve stone heritages, and several researches have been conducted (Meiklejohn 1997, Heinrichs 2008, Roussel 2013). It is also necessary to give proper treatment towards stone structures in order to keep heritages in good conditions. Bugani et al. (2008) conducted the treatment towards biocalcarenite using polymers, and structural change inside of the rock sample is evaluated by μ-focus X-ray CT data. In Japan, reinforcement material based on orthosilicic acid ethyl ester has been used. However, there are still problems such as exfoliation at the border between the reinforcement and rock matrix or durability.
