Evaluation of Factors Affecting the Performance of Geogrid-Reinforced Granular Base Material Using Repeated Load Triaxial Tests

Abstract

This research evaluated the benefits of geogrid reinforcement of granular base specimens and studied the effect of different factors contributing to their performance. This includes geometry, tensile modulus, arrangement/location of geogrids, the moisture content of specimen, and stress state. Five geogrids of different tensile modulus and aperture geometries (three rectangle or biaxial and two triangle or triaxial) were used. The study was experimentally carried out by conducting repeated load triaxial (RLT) tests to evaluate the resilient and permanent deformations of the specimens. The test results demonstrated the potential benefit in placing the geogrid within the granular base specimens. Less permanent deformations were measured under cyclic loading for geogrid-reinforced base specimens compared to unreinforced specimens. The geogrid geometry and tensile modulus had noticeable effects on the specimens’ performance. Of the five geogrids used, the triaxial geogrid (TX1) with triangle geometry and the highest tensile modulus performed consistently better than the other four geogrids. For geogrids with the same geometry, the higher the tensile modulus, the lower was the accumulated permanent deformation. The test results also showed obvious effects of the geogrid arrangement/location on the specimens’ performance, with the double geogrid location consistently yielding the largest improvement. The test results did not show any appreciable improvement in the resilient deformation or resilient modulus of the geogrid-reinforced granular specimens. The effect of moisture content on the performance of geogrid-reinforced specimens was evident, with higher improvement observed for specimens prepared at the optimum and dry of optimum than those prepared at wet of optimum.