A study of the effect of temperature on the structural strength of a clayey soil using a micropenetrometer

The effects of temperature on the behaviour of soils are of great concern in many geotechnical applications. This paper reports an experimental study that focused on the effect of temperature (between 20 and 50 °C) on the structural strength of a clayey soil using a modified micropenetrometer. Laboratory penetration tests using two penetration rates were conducted on highly overconsolidated specimens for which the degree of saturation (Sr) and dry density (ρd) were controlled. The results indicated that the penetration resistance (the total resistance, the friction and the end resistance) decreased with increasing temperature, suggesting that the structural strength of soil was softened by increasing the temperature. In addition, the rate of decrease in structural strength with increasing temperature was greater when the degrees of saturation was low and the dry density was high. Tests performed under cyclic heating and cooling revealed that subjecting the soil to this thermal cycling improves its structural strength. Moreover, increasing the rate of penetration caused higher penetration resistance, while its influence on the thermomechanical behaviour of the soil was only very slight