PERFORMANCE STUDY OF GEOGRID REINFORCED FLEXIBLE PAVEMENT ON SOFT SOIL

The road network plays a very important role in the socio-economic development of any country. The design and construction of flexible pavements on soft soils is quite challenging and problematic task because the compressibility of soft soils is very high which affect the service life of the pavements. Several stabilization techniques are available for such scenarios. Among all utilization of geosynthetics has been popular due to their high performance, ease of construction and economy. Geosynthetics include geotextiles, geogrids, geomembranes, geo-composites and, geocells available for pavement construction among which geogrids are popular because of their stiffness and rigidity nature. Though there are many studies discuss about the geogrid stabilized pavement base layers, no proper understanding has been developed to design geogrid reinforced flexible pavement as per Indian context. So in this study, a modified design methodology has been used to design the reinforced flexible pavement which is developed with the help of IRC: 37-2012 and AASHTO-1993. Rutting and fatigue strain of the pavement were checked with IITPAVE software. In this study, Large scale static load tests were performed to replicate the actual field conditions in the test tank of inside dimension 1.5m x 1.5m x 1.0m (Length x Breadth x Height) on various subgrades and base layers with and without geogrids. Static load was applied through a graphical user interfaced multi-purpose test software along with the help of a hydraulic power unit, hydraulic service manifold and sophisticated double acting linear dynamic 100kN capacity actuator which is connected to a 3.5m high, 200 kN capacity reaction frame. The performance improvement has been presented in terms of layer coefficient ratios (LCR), modulus improvement factor (MIF), resilient modulus (Mr) and California bearing ratio (CBR). Based on the laboratory test data, it was shown that the total thicknesses of the pavement layers were reduced by enhancing the performance of the pavements. It was also shown that there will be huge savings of materials per kilometer per lane of a road designed and construction with geogrid reinforcement on soft soils (CBR-3% & 5%)