In railroad construction, base layers of unbound coarse-grained material are usually installed between the existing subsoil and the rail track. Geosynthetics, in particular geogrids, are used to improve the system behaviour. The reduction of the base layer thickness by the geogrid is based on empirical approaches. The influence of the geogrid on the load-bearing behavior of a base course is to be quantified by experimental investigations. The investigation is performed using a downscaled base course material and geogrid. For this purpose, monotonic and cyclic triaxial tests were performed to demonstrate the failure and the cyclic loading behaviour. In the monotonic triaxial tests the specimens were sheared to failure. The positive influence of the geogrids compared to the unreinforced specimens could be quantified. Since the in-situ stresses are mainly in the service load range and thus the failure state is not reached, but the stress follows a high number of load cycles, cyclic triaxial tests were performed. The test specimens were loaded cyclically in order to investigate the influence of the geogrid on the deformation accumulation. The cyclically loaded specimens thus show the influence of the geogrid on deformation accumulation. As a result, a reduction in deformation accumulation due to the geogrid could be demonstrated.