Compression behaviour of reconstituted soils at high initial water contents

Oedometer tests starting from a very small effective vertical stress of 0·5 kPa were performed on three reconstituted clays with different liquid limits. The soils were prepared at various initial water contents, ranging from 0·7 to 2·0 times their corresponding liquid limits. It is observed that the e–log Formula: see text compression curves show an inverse ‘S' shape due to suction pressure resisting deformation, similar to that of soft natural clays caused by consolidation yield stress. The suction pressure Formula: see text of the reconstituted clays can be correlated with the ratio of initial void ratio to void ratio at liquid limit e 0 /e L . The suction pressure curve defined by a unique relationship between suction pressure Formula: see text and the normalised void ratio at suction pressure e s /e L is also proposed to distinguish between the pre-suction and the post-suction states. In addition, Burland's concept of the intrinsic compression line is adopted for correlating the compression curves of various reconstituted clays at high initial water contents. It has been found that the void index is a powerful parameter for normalising the compression curves in the post-suction state. Nevertheless, it seems that Burland's intrinsic compression line slightly underestimates the void index at the low stresses considered in this study. An extended intrinsic compression line is then derived in order to better fit the data for stresses lower than 25 kPa.