Coupled effects of initial water content and swelling history on compression behaviors of bentonite

Abstract

This study experimentally investigates the coupled effects of initial water content and swelling history (i.e., free swelling, no swelling, and confined swelling) on compression behaviors of bentonite via two suites of swelling tests and four sets of one-dimensional compression tests. The initial water content has an influence on the swelling behavior of bentonite in both free swelling and confined swelling conditions. Additional insight and numerical models were provided on the prediction of bentonite swelling under different conditions. The swelling history was found to have significant effect on the compression behavior of bentonite. Results showed that the compression curves of bentonite exhibited differently under different swelling histories at the same initial water content. The effect was observed less significant as the consolidation pressure increased to the pre-consolidation stress. The yielding stress of remolded bentonite decreases with increasing initial water content regardless of swelling history; however, that of bentonite specimen with free swelling was lower than that with confined swelling at given initial water content. The difference of void ratio caused by the swelling history is the primary factor that results the different compression behaviors. It was found to related with the change in bonded water that developed during the swelling process. These results demonstrate that it is essential to consider the coupled effects of initial water content and swelling history on the compression behaviors of bentonites upon engineering application.