Study of the rheological properties of clayey suspensions: an interest in the field of landfills

Abstract

In the landfill bottom liners design process, geotechnical tests of long duration time are often conducted to ensure the presence of reactive clays and to assess their hydromechanical properties. This study aims to show the interest of the rheometry of clayey suspensions as an alternative tool for identifying clays and determining the shear strength of bottom liners. An experimental protocol, using a six-speed rotary viscometer, was first implemented on bentonite suspensions on the one hand and kaolinite suspensions on the other. The results show that to have similar shear strengths (between 1.0 and 25.4 Pa), the concentration ranges used for these two types of suspensions must be totally different: between 600 to 1200 g/L for kaolinite and 30 to 90 g/L for bentonite, confirming the usefulness of rheometry as a tool for identifying clays. Furthermore, results from rheometry tests also show an increase in the shear stress of kaolinite suspensions when there are made with leachate; such results are in agreement with geotechnical shear tests conducted on compacted samples. This study is of practical use for environmental geotechnics professionals because it offers an alternative to traditional geotechnical tests.