Evaluation of hydromechanical behavior and macro-structure of an expansive soil in the city of Paulista-PE Brazil

Abstract

The characterization of the structural arrangement of an unsaturated soil is important for the understanding of its behavior. For expansive soils, obtaining this information and combining it with an understanding of their intrinsic and extrinsic properties, makes it possible to predict their performance. The experimental procedure for this study was developed using the expansive soil of the Maria Farinha formation in the city of Paulista, in Pernambuco, Brazil. Physical and chemical characterization tests, edometric tests with wetting, and structural analysis through X-Ray computed tomography were performed for both undisturbed and compacted samples, before and after wetting and swelling. The compaction process was performed without any prior air drying and without loosening, beginning with the field moisture level. Based on its liquid limit and plasticity index, the soil can be classified as CH according to the USCS, moderately acidic, with a swelling potential ranging from high to very high, depending on the initial suction of the sample. The analysis of the soil macro-structure revealed a smaller number of voids in the compacted samples. In addition, it was found that the wetting process caused a reduction of the soil macro pores, in both cases.