Behaviour of jute and bamboo geocell with additional basal mat filled with different infill materials overlaying soft subgrade

Road construction and maintenance over a soft subgrade are challenging tasks. In the last few decades, polymeric geosynthetic materials are used to reinforce weak subgrade for better durability and cost-effectiveness. Natural geosynthetic materials such as bamboo, jute, and coir, have the potential for road construction and can be used in place of polymeric geosynthetics. In this present study, model plate load tests were performed to evaluate jute and bamboo geocell performance with an additional basal mat overlaying soft subgrade for the unpaved roads. The influence of infill material was studied with three different types of infill materials, i.e., sand, crushed aggregates, and Recycled Asphalt Pavement (RAP). Further, the size effect of infill material was studied by preparing three different crushed aggregate mixes (i.e., mix A, mix B, mix C) using the Fuller method of gradation. For the unreinforced and geocell reinforced system, the load-bearing capacity was found maximum with RAP and minimum with sand. Further, with an additional basal mat, the load-bearing capacity was maximum with mix C. The improvement factor (IF) with jute geocell was found in the range of 4–14.6 and enhanced to 5.1–18 with additional use of jute mat. However, using bamboo geocell, IF was found in the range of 5.1–16.9 and enhanced to 9.3–26.9 with additional use of the bamboo mat. The contribution of both types of geocell reinforcement was found maximum with sand and minimum in RAP as infill material. However, the contribution of the mat was found maximum with mix C and RAP for jute geocell and bamboo geocell, respectively. The infill material size effect was found negligible beyond mix B (i.e., the maximum size of aggregate 25 mm). The performance of the bamboo geocell was observed superior to the jute geocell. RAP and crushed aggregate mixes (mix B and mix C) are found as preferable infill materials of the geocell for maximum bearing capacity.