Total suction is the sum of the matric and the osmotic suction of the soil. Various methods are used to measure the total suction of the soil. One of the methods is the chilled–mirror hygrometer technique. The chilled-mirror device employs a dew-point procedure, which is one of the most accurate and valuable methods for measuring total suction in the mid- to high- total suction range.
The effect of the percentage of gypsum on the total suction estimation for a gypsum-sand mixture has been investigated rarely in the past. In this paper, the total suction is determined for soil specimens containing different percentages of gypsum additive mixed with Silber sand. The soil specimens were prepared at different initial conditions of density and degree of saturation in order to investigate a wide range of physical soil properties. The test results showed that an incremental increase in the percentage of gypsum and degree of saturation of a soil mixture caused a reduction in the measured value of total suction, while an increase in the initial dry density caused the measured total suction to remain almost unchanged. No constant trend is observed with respect to the effect of the curing time on the measured total suction.