Shrinkage Curves for Powder and Granular Bentonites

Abstract

Bentonite is one of the most commonly used materials in geotechnical engineering applications especially for isolation purposes due its low permeability and its highly expansive nature. For instance, Geosynthetic Clay Liners (GCL) self-healing ability relies on the swelling properties of the bentonite to close any holes in the GCL while the low permeability of the bentonite serves to reduce the infiltration of leachate to the surrounding soil. However, different types of bentonite have different shrinkage or swelling properties and hence affects the effectiveness of the GCL. A method to assess the wetting/drying induced volume change of the bentonite is through its shrinkage curve. This paper focuses on the shrinkage behaviour of reconstituted granular and powder bentonites which are used in GCL. Photogrammetry method is used to measure the volume change of specimen during drying. The shrinkage curves of the bentonites are then compared with other bentonites from the literature.

Numerical Simulation on the Effect of Infiltration and Evapotranspiration on the Residual Slope

“…SWCC is a curve relating to water content and suction of a soil, which can be represented by gravimetric water content (w), volumetric water content (θ) and degree of saturation (S) [15,16], while permeability function represents changes in permeability due to the changes in soil suction [17]. It is important to note that several known unsaturated soil behaviors are commonly ignored when conducting numerical analysis, such as: 1. effect of shrinkage, which causes gravimetric water content based SWCC (SWCC-w), volumetric water content based SWCC (SWCC-θ) and degree of saturation based SWCC (SWCC-S) to be different [15,18]; 2. hysteresis between drying and wetting SWCC [19][20][21]; 3. change in SWCC due to change in density [22]; and 4. permeability function, which could be different when it is estimated from SWCC-w, SWCC-θ and SWCC-S [23].…”

Mechanical Behavior of Fiber-Reinforced Soils under Undrained Triaxial Loading Conditions

“…The fiber-reinforced soils in applications such as embankments and pavements are usually unsaturated both at the construction and operation stages. Significant research work has been carried out on the behavior of unsaturated soils (e.g., [30][31][32][33]) and the unsaturated shear strength of unreinforced soils (e.g., [34,35]) and the unsaturated soil mechanics principles were applied successfully in the design and construction of a capillary barrier system used as a slope protective measure [36]. However, the measurement of the shear strength of unsaturated soils is costly and time-consuming and requires special laboratory equipment [34,35].…”