Evaluation of flexural behaviour of geosynthetic-reinforced unbound granular material beams

Nowadays, geosynthetics offer cost-effective and sustainable materials for pavement construction which enhance pavement performance. As the geosynthetic layer acts as a flexible member embedded within the pavement structure, the flexural behaviour is an important aspect to consider for the use of geosynthetics. Therefore, in this study, the flexural behaviour of geosynthetic-reinforced unbound granular materials was investigated by carrying out a series of four-point bending tests. The geosynthetic reinforcement considered involves geogrid and geocell. Silty sand and crushed aggregate were considered as infill materials. Unreinforced and geogrid/geocell-reinforced three-layered beams were constructed using polywood, plywood, selected infill materials and geogrid/geocell. Provision of the geogrid/geocell proved to provide significant resistance against the lateral spreading of the infill material when compared with the unreinforced infill materials. The resistance to lateral spread increases with an increase in the aspect ratio of geocells and the position of geogrid. The elastic modulus of the geogrid/geocell-reinforced infill materials is found to increase significantly when compared to that of the unreinforced materials with geocell reinforcement being very effective. Geogrid placed 25%H from the bottom is found to possess higher elastic modulus when compared with the geogrid placed at 50%H and 75%H from the bottom of the middle layer. The provision of geogrid/geocell within the granular sub-base of a pavement significantly improves the rutting life of the pavement. An attempt is also made to develop an empirical model for the prediction of Es of unreinforced and geocell-reinforced infill materials. There is a good agreement between the predicted and laboratory Es values with an error of 5%. The model enables the analytical design of flexible pavement incorporating geocells.