A Bench-Scale Performance Test for Evaluation the Geosynthetic Reinforcement Effects on Granular Base Courses

The objective of this study is to evaluate a proposed bench-scale performance test for determining the best location for geosynthetic placement for base reinforcement applications. The ASTM D1196 standard test method was incorporated in the proposed bench-scale test. A standard servo controlled universal compression test machine was used as the loading device. A series of performance test program was conducted. The test soil was compacted in a steel test tank designed to fit inside the test machine. Three uniform graded granular soils, rounded white quartz sand, a brownie gray rounded riverbed medium gravel and a large white rounded marble gravel, were selected. Geosynthetic reinforcement materials included a high-strength polypropylene geotextile, two types of uni-axial geogrids, and one biaxial geogrid. Two steel circular plates with diameters of 150 mm and 300 mm were used to simulate the footprint of various sized tires. Geosynthetic specimens were placed at depths of 5cm, 10cm, and 15cm for each type of test soil and geosynthetic reinforcement. The proposed bench-scale performance test found is a simple, economical, and effective approach to evaluate the effect of geosynthetic for base reinforcement application. The results from this investigation indicated that the geosynthetic reinforcement placed at a depth of 5 cm showed the best reinforcement effect for the various test soils. Placing the geosynthetic at a depth of 15cm or below showed almost no reinforcement effect. This result was applicable for all of the different test soils and various load plate sizes. Using biaxial geogrids with apertures equal to D₅₀ of the reinforced soil provided the best reinforcement effect for coarse granular materials. A 10cm overburden over the reinforcement materials provided sufficient pressure to fix the reinforcement in place for the base reinforcement application. Boundary effect can be significant reduced as conducting the test with 300 mm load plate by placing a layer of soft padding material around the inside perimeter of the test tank.