The Kyushu Research Institute for Cultural Properties Inc. and Kumamoto University have introduced the Aquo-Siloxane method, a new method for preserving stone heritage sites. In this study, the Aquo-Siloxane method was applied to weathered rock samples and verified the effect of the technique. Samples were taken from gravestones made of Amakusa Shimoura sandstone. The gravestones were constructed in different eras, the Edo era (approximately 200 years ago) and Meiji Era (approximately 100 years ago), and have been left exposed. Here, water permeation and capillary tests were conducted on the samples with and without Aquo-siloxane treatment, and the inhibitory effects of water migration on weathered porous sandstone were checked. Permeability improved and the movement of water flow was restricted. The inner structure of the samples was observed by an X-ray CT scanner and porosity distributions were evaluated. Capillary tests were also conducted and the migration of water in pores was visualized by an X-ray CT scanner. Aquo-Siloxane method has been found to be effective at preventing moisture migration in pores and is a promising technique to preserve weathered rock heritages.

1. Introduction

Stones and rocks are important construction materials, and various types of buildings, statues, towers, and graves are constructed from rock. Many are recognized as historically and culturally important heritage sites, and they should be passed on to generations in good condition (Al-Omari et al., 2015; Maraveas et al., 2015; Torok et al., 2015). In order to protect stone heritage sites, the Kyushu Research Institute for Cultural Properties Inc. and Kumamoto University have introduced a new method, the Aquo-Siloxane method. By applying this method, it was found that the permeability of porous rock samples could be reduced and that water absorption due to capillary action into rock samples was also reduced (Sato et al., 2012; 2015). Moreover, the method exerted a water repellent effect on the rock samples. This is a preferable effect to keep the stone artifacts in good condition. These studies were conducted on unweathered and relatively fresh rock samples. However, the stone artifacts have generally been exposed to rains and wind for extended periods, and many of them are weathered to some extent. Therefore, it is necessary to verify the effect of the method towards weathered rocks.

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