8th Asia-Pacific Conference on Unsaturated Soils, Melbourne, Avustralya, 4 - 06 Aralık 2024, ss.1-5, (Tam Metin Bildiri)
The Soil Water Retention Curve (SWRC) is an important property of unsaturated soils, representing the amount of water in a soil and the corresponding suction. Measuring the tail end of the curve in the laboratory involves the application of very high constant suctions. A common method employed for this purpose is the vapour equilibrium technique, where suction is imposed on soil specimens sealed in closed containers in humidity equilibrium with a saturated salt solution at a unique relative humidity and total suction. This paper presents a methodology for altering the temperatures of the salt solutions such that a variety of suction levels are achieved for each type of salt. In this way, a greater number of points can be plotted on the SWRC and a more fleshed-out curve can be obtained in the high suction range. Three different methods of temperature control were used: a refrigerator, a low-temperature oven, and a thermal insulation box kept at room temperature. Five different salt solutions were employed inside each of the three temperature-controlled chambers. Air-dry and saturated specimens of a sample of high-plasticity Ankara clay were tested separately for the wetting and drying curves. Volume measurements were also taken at the end of the equilibrium period, to account for swelling or shrinking, resulting in well-defined SWRCs plotted against degree of saturation.