『Abstract
　The description and classification of the rocks provide important information for geotechnical modeling in order to predict their engineering behaviors. One of the most imperative parameters influencing the engineering behaviors of the rocks is the degree of weathering. Therefore, it is evident that a realistic weathering classification is necessary mostly for establishing the geotechnical models in the engineering geology studies. For this reason, development of a qualitative weathering classification is the main purpose of the present study. The Weathering State Parameter has been first created by describing the chemical and physical changes separately owing to weathering by employing the ultrasonic wave velocity in the rock material. Then a quantitative weathering index was introduced by combining the weathering condition and the slake-durability known as the indicator of the rock.soil ratio in the rock material. Finally, this index obtained was applied on the prediction of the engineering properties of the Harsit granitic rocks (Giresun, NE Turkey). As a consequence of this study, it has been determined that the engineering properties of the samples and the numerical index proposed could be predicted. In addition, the use and the limitations of the index introduced herein were discussed.

Keywords: Igneous rocks; Weathering; Quantitative classification; Weathering index』

Introduction
Background on the weathering descriptions based on mineralogical and physical changes
A proposal to describe a quantitative weathering classification for igneous rocks
Application for the Harsit（sにセディーユが付く） granitic rocks
　Geological setting of the sampling area
　Sample preparation and testing
General properties of the Harsit Granitoid samples in different weathering classes
　Fresh granite
　Slightly weathered granite
　Moderately weathered granite
　Highly weathered granite
　Completely weathered granite
　Residual soil
Statistical analyses
Results and conclusions
References