In the evaluation of unsaturated soil behavior in the laboratory, it is required to measure the total volume change of triaxial soil specimens. This, however, is not an easy task, with setups proposed in the literature being quite expensive or presenting variable setbacks. In this context, this article presents a new, reliable, cheap system to estimate the total volume change of the soil in unsaturated conditions in triaxial tests. To do so, a double-chamber triaxial cell was developed, with the inner cell connected to an air-tight container subjected to the same cell pressure and positioned on a precision analytical scale. The measure of the total volume change is given by the mass of water entering or leaving the air-tight container. After calibration, the system was tested under consolidation using saturated soil samples. Comparing the conventional change in water volume of the saturated specimen with the variation of the total volume obtained through the developed system, a maximum difference of 0.01 cm3 is obtained, which equals only 0.01 % of the specimen volume. The effects of temperature and of cell pressure variation, which might occur during the saturation of unsaturated specimens in conventional triaxial tests, are also presented and discussed.

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The evaluation of soil-water characteristic curve is one of the most important procedures in the matter of understanding the soil behaviour during wetting and drying processes. Even though it might be carried out by established methods, this practice is considered a time-consuming technique, and because of this it is still under-used in comparison with its potential applications. In this way, this paper aims to analyse the correlation of soil suction and soil resistivity to produce a time-reduced soil-water characteristic curve (SWCC), based on resistivity measured values. To perform this research, it was used a set of soil samples collected from Nova Friburgo, Rio de Janeiro – Brazil. The material was geotechnically characterized by standard methods. To determine the (SWCC), it was used the filter paper method and the volumetric water content/suctions were obtained by wetting and drying stages for two paths that emerged from the field moisture content. The results revealed a remarkable relationship between suction and the resistivity measured data, emphasizing the feasibility of determining the Soil-Water Characteristic Curve by resistivity measurements, here named Soil-Water Resistivity Curve (SWResC).