『Abstract
　Weathering can cause adverse effects on the physico-mechanical properties of rocks. Although the processes and outcomes of weathering have been investigated for many rock types, the travertine weathering was not paid enough attention as much as the others. However, the unfavorable effects of weathering may arise rapidly due to travertine's calcium carbonate composition and highly porous texture. Travertine is an important rock type in building stone market and is generally preferred as an exterior facade（cにセディーユが付く） material. This rock type was also used in many historical buildings and sculptures in the past, and the signs of extensive weathering can be recognized on some of these travertine-made structures. In this study, it was aimed to characterize the effect of weathering on travertine's structural properties. The yellow travertine from Eskipazar (Karabuk, Turkey) was selected as the study material and the samples with different weathering degrees were collected from site. The chemical, physical and mechanical properties of those samples were determined in laboratory. The physico-mechanical variations with progressive weathering grades were statistically evaluated and a weathering classification based on a rating system was proposed for yellow travertine in rock material scale. The newly developed system may assist in characterizing the degree of weathering for historical structures built by yellow travertine. Additionally, the classification may also guide to further researches on the weathering of different types of travertine.

Keywords: Travertine; Rock material weathering; Weathering classification; Eskipazar; Factor analysis』

Introduction
Material
Methodology
Characterization of in situ weathering grades by visual indicators
X-ray diffraction, scanning electron microscope, and chemical analyses
Effect of weathering on physical and mechanical properties of yellow travertine
Proposed rock material weathering classification for yellow travertine
Conclusions
Acknowledgments
References