The article shows the analysis of the behavior at long-term deformation of geocells for a set time period, due to its importance on the modulus improvement factor (MIF), which is considered in the design stage of a reinforced pavement structure with geocells. When inquiring into the research about the structural behavior that exists in the geocells, as well as the distribution of stresses that this generates, in order to determine how important the existence of a deformation in the geocell is. We proceeded with the sampling and execution of the test "modified stepped isothermal method (SIM) for geocells." The test was carried out under the comparison of the materials and thicknesses of the sample, with the purpose to analyze the influence on the behavior of a pavement structure. The stresses generated at the level of the granular subbase layer of a pavement are taken into account as load effects.