ABSTRACT: One of the major challenges in the implementation of solid waste landfills is the high degree of control of the leachate produced in the system. The watertightness of these systems is guaranteed by the use of hydraulic barriers, currently composed, for the most part, of geomembranes and bentonite geocomposites (or GCL). In this context, the study of the performance of the GCL is fundamental, since this layer acts as a hydraulic safety barrier. Currently, the main concern is the retraction behavior of this material, which occurs mainly during the construction stage, when it is exposed to the elements. Naturally, the risk of soil and water bodies contamination is significantly increased as a function of this problem. Recent work has shown that the values ​​of initial moisture of the GCL and the dynamics of hydration and rehydration of this material by the subgrade are preponderant factors in the behavior of the retraction effect. Exposure to daily thermal cycles imposes a loss of moisture from the GCL to the foundation soil. However, there are certain moisture contents in which the subgrade can rehydrate this material, canceling or attenuating the significant loss of humidity and, consequently, the retraction values ​​found. This aspect has not yet been evaluated in tropical climate conditions, such as in Brazil, where fine soils tend to have higher moisture contents than those observed in temperate countries, as well as situations with lateritic soils. Considering the above and the field conditions that GCL may be subjected to, the present work evaluated the retraction of a sample of GCLs (Liner Geombrana-GCL) with initial moisture of 12% submitted to 20 heating and cooling cycles (8 hours) on a clay soil compacted with 26% moisture. The results showed a 2% shrinkage in the sample, revealing the potential for damage of the retraction effect even in the case of a reduced number of cycles. It was also observed a moisture loss of the foundation soil for the GCL and the condensation of the air humidity present between the GCL and the Geomebrana.