Solos expansivos no Brasil: uma revisão sistemática.

Abstract

Expansive soils are problematic soils that represent a challenge for infrastructure works in civil construction. In dry seasons, these soils may show cracks, due to their contraction. In the more humid seasons, when they absorb water so they expand, which can destabilize foundations and even raise structures. This expansion takes place through two mechanisms, mechanical and physical-chemical. The combination of these mechanisms directly interferes with the change in volume of expansive soils. Usually, these types of soil are found in arid and semi-arid areas, which favor the formation of unstable clay minerals responsible for their expansive character. Brazil for having a vast region with a semi-arid climate, territories with the presence of expansive soils are diverse, however little is known about this. To track the expansive soils studied in Brazil, answer some specific questions objectively and impartially and guide future research, a systematic review of the literature focused on expansive soils in Brazil was done, associating a set of studies available in the CAPES Theses and Dissertations catalog. With this study it became clear that although the problem of expansive soils is pertinent, very few researchers are focused on this problem. Most research focuses on soils from Pernambuco, that make up the Brazilian semiarid region. However, among the regions that are part of the Brazilian semiarid region, only samples from regions in the state of Pernambuco were used as the object of studies. In addition to the soils of these states, soil samples from regions such as São Paulo, Santa Catarina, and Paraná, and Rio Grande do Sul were studied. No agreement was found for the studied soils between the results of qualitative indirect methods and direct quantitative methods. The expansive soils presented, in their majority, high content of grains smaller than 0,075 mm, were classified as highly plastic, however with clay fraction classified as inactive. The average expansion, in the free expansion test, was 11,7% and the average expansion pressure was 162 kPa. It was also noticed a great variability in the parameters used by the methods to classify the soils as expansive.