Correlation between shale index properties derived from different sample preparation procedures

Shale samples covering a wide range of plasticity and gradation were tested to yield quantitative data required to establish reliable correlations between index properties derived from standard and modified sample preparation procedures. The study revealed that the degree of shale particle disaggregation has an important influence on the measured liquid limit and clay-size fraction. This influence is maximized for shales with intermediate plasticity and can be interpreted in terms of particle size and shape. It is recommended to use the correlations presented in this paper to adjust shale index properties derived from standard sample preparation procedures usually utilized by commercial laboratories. Such correlations help in creating a universally followed procedure for better estimation of shale engineering properties and reliable interpretation of case histories involving shale formations.