The temperature effects on hydraulic conductivity of compacted bentonite

The hydraulic conductivities of water saturated Ca-bentonite with dry densities of 1.4, 1.6, and 1.8 Mg/m³ were measured within the temperature range of 20 to 80°C. The hydraulic conductivities of all the compacted bentonites are lower than 10⁻¹¹ m/s, and the relationship between the logarithm of the hydraulic conductivity and the bentonite dry density can be fitted to a straight line. The hydraulic conductivities of bentonites increase with increasing temperature, and the hydraulic conductivities at 80°C increase up to about three times those at 20°C. The measured values are in agreement with those predicted from the hydraulic conductivities at 20°C assuming that only fluid properties are changed with changing temperature. The change in viscosity of water with increasing temperature contributes greatly to the increase of hydraulic conductivity.