Effect of water content on hydraulic properties of bentonite–geomaterials mixture

Abstract

This article examines the effect of water content on hydraulic properties of bentonite–geomaterials mixture. The relationship between the initial water content, matric suction and hydraulic conductivity (saturated and unsaturated) and the soil–water characteristic curve were controlled established during a laboratory test. Three materials were used during this study: bentonite and two types of geomaterials . First, the mixture of 10% bentonite–20% calcareous sand–70% tuff was selected on the basis of the minimum saturated hydraulic conductivity (k sat) . The results showed that the effect of the initial variation in water content from 12.35% to 16.35% does not make a difference in the k sat values; the values are between 10−8 and 10−11 m/s. Then, the effect of the initial water content on the soil–water characteristic curve was studied using suction control methods. The soil–water characteristic curves showed that the air entry value (AEV) increases with decreasing initial water content The unsaturated hydraulic conductivity (k w) study with different initial water content was measured with an original vapour equilibrium technique (VET). The results showed that the k w varied between 3 × 10−17 and 4 × 10−15 m/s in all cases of initial water . In addition, the Van Genuchten hydraulic conductivity model is compared to the experimental results. . Finally, the effect of the initial water content on the saturated and unsaturated hydraulic conductivity of this mixture is not apparent for the much lower (Sr > 80%, k = k sat) and very high suction values, respectively.