Resilient modulus of crushed stone material reinforced with geogrids

Abstract

Unbound base layers can be stabilized with geogrids that reduce lateral movement of granular material thus improving its stiffness through particle interlocking inside geogrid openings. Good particles-geogrid interlocking depends significantly on the ratio of geogrid aperture size to the average soil particle size. This paper describes testing of a resilient modulus and a permanent deformation of geogrid reinforced granular material. Biaxial and triaxial geogrids made with 3D printer were used in which geogrids were of different aperture sizes and rib thickness. It was thus possible to test parametrically the effect of geogrid geometry and rib stiffness on the resilient behaviour and permanent deformations. Experiments were conducted on cylindrical specimens of 160 mm diameter and 320 mm height and were reinforced with one or several layers of geogrids. The results of cyclic triaxial tests for unreinforced and reinforced specimens with created geogrids are presented in the paper, as well as the results of the previous research on commercially available geogrids. It is observed from the presented results that resilient behaviour of the tested granular material was not improved with the use of geogrids, while geogrids gave certain improvement with respect to permanent deformations. Presented research is a part of the ongoing project at the University of J.J. Strossmayer in Osijek and the Slovenian National Building and Civil Engineering Institute.