The mechanical properties of soils and, thus, of soil structures can be improved by using geosynthetic reinforcements. This beneficial effect depends on several parameters. Herein the mechanical response of the soil-geosynthetic composite material was studied using triaxial tests and the influence of the following parameters on the stress-strain response of the soil was analysed: effect of the reinforce-ment, number of reinforcement layers, vertical spacing between reinforcement layers; influence of the specimens’ dimensions. The soil was a well graded sand with silt (8% of fine particles); the geosynthetic was a reinforcement geocomposite consisting of continuous filament non-woven, reinforced by high te-nacity polyester yarns material. The stress-strain response of the reinforced soil was compared to that of the unreinforced soil tested under the same conditions, using triaxial tests. The inclusions improved the stress-strain response of the composite material, due to the additional confinement provided by the rein-forcements; the compressibility of the reinforcement and the lack of large openings influence the volu-metric strains. Increasing the number of reinforcement layers from 1 to 3 resulted in an improved stress-strain response of the reinforced soil, particularly for large strains. For lower strains the reinforcements had no significant influence on the load-strain curves of the specimens. The height of soil between adja-cent layers of reinforcement is key to the performance of the reinforced soil specimens. The small dimen-sion of the specimens may lead to overestimating the benefit from the reinforcement, particularly for low confining stress.