Influences of solution and mixed soil on estimating bentonite content in slurry using electrical conductivity

Successful construction of soil–bentonite barrier system requires monitoring of the bentonite content during construction to ensure that the quantity of bentonite is adequate and the distribution of bentonite is uniform. In this study, factors affecting the electrical properties of bentonite slurry were identified and electric conduction mechanisms which prevail in bentonite slurry were examined. The electrical conductivity of both bentonite and soil–bentonite slurries linearly increased with bentonite content due to the dissolution of cations from bentonite particles. The linear relationship between electrical conductivity and bentonite content was affected by the solution electrical conductivity and fine content in soil–bentonite mixture. As the initial solution electrical conductivity increased, the slope of the regression lines decreased. In addition, the y-intercept was found to increase slightly with an increase in fine content. The empirical relationship between electrical conductivity and bentonite content considering the combined influence of fine content and slurry solution was derived. Based on the suggested relationships, the bentonite content in bentonite and soil–bentonite slurry can be quantitatively evaluated by using an electrical conductivity measurement method.