Soil-water characteristic curves of bentonites in isochoric conditions during wetting: measurement and prediction

Abstract

The determination of the soil-water characteristic curve (SWCC) of compacted bentonites in the isochoric condition is a prerequisite for unsaturated flow simulations in several geoenvironmental applications. The SWCC data are, however, not readily available for many compacted bentonites over a wide suction range due to difficulties associated with the testing. In this work, wetting SWCCs of four Indian bentonites of different plasticity were established experimentally at compaction dry densities of 1.4, 1.6, and 1.8 Mg/m3 in isochoric conditions using two independent laboratory techniques in different suction ranges. The modified Kovács (MK) model was extended to simulate the SWCC data of the Indian bentonites. Empirical relationships between MK model parameters and compaction dry density for these bentonites were established. A theoretical procedure for the estimation of SWCCs of the compacted bentonites based on the basic bentonite properties and proposed correlations was proposed and validated on the available wetting SWCC data of compacted GaoMiaoZi (GMZ), MX80, and FEBEX bentonites from the literature studies. The proposed method predicts the wetting SWCCs of compacted powder bentonites, in volume-restrained condition, from the basic properties satisfactorily. The proposed model is an approximate method for predicting the SWCCs of bentonites in the absence of measured data and in understanding the influence of dry density and plasticity.