Investigation on swelling characteristics of GMZ bentonite with different initial water contents

Abstract

Compacted bentonite has been identified as a suitable buffer material in the field of nuclear waste disposal due largely to its exceptional swelling potential. This study presents the swelling characteristics of compacted bentonite (1.50 Mg/m3) with different initial water content (5.0–29.0 %), accompanied with microstructural observation. Results showed that the swelling pressure was almost unchanged when the initial water content was less than 19.8 %, above which the swelling pressure continuously decreased by 25.9 %. The swelling deformation generally decreased with increasing initial water content, by up to 54.9 %. Microstructure features of specimens were largely affected by water contents and uniaxial compaction was expected to induce different degrees of anisotropy. This probably results in the variation in swelling potential of compacted bentonite, due to varying macro-microstructure coupling. The present study presents a new idea for the optimal design and manufacture of bentonite blocks.