PERFORMANCE OF REINFORCED BASE COURSES OF FLEXIBLE PAVEMENTS OVERLYING SOFT SUBGRADES: INSIGHTS FROM LARGE-SCALE MODEL EXPERIMENTS

Abstract

In this study, large-scale model pavement experiments (LSMPEs) were performed to assess the performance of geosynthetic-reinforced bases of flexible pavements overlying soft subgrades (with California bearing ratio equal to 1% and 5%). Two configurations of reinforcement were considered – (1) base layers reinforced with geocell (GC) alone, and (2) base layers reinforced with geocell and geogrid (GG) combinations (GC+GG). Model pavements were constructed inside the test chamber measuring 1.5m (length) × 1.5m (width) × 1.0m (height). Wheel loads on the pavements were simulated by applying repetitive load equivalent to the tire contact pressure of 550 kPa through an actuator on a rigid circular plate (diameter equal to 300 mm). The reinforcement combination with GC+GG was found to perform better than GC alone due to additional support offered by geogrid when used as a base or basal reinforcement underneath the geocell mattress. The performance was evaluated in terms of cumulative permanent deformations and Traffic Benefit Ratio (TBR) over 100,000 repetitive load cycles. TBRs of the GC+GG combination showed values greater than 50 for test conditions considered. Furthermore, test results showed that the GC+GG combination reduced permanent deformation by up to 78%, while GC alone reduced it by about 52% compared to the unreinforced section. TBRs of geocell alone and geocell with basal geogrid combinations indicated extended service life of the pavement