Performance of geogrid- and geotextile- reinforced low to moderately expansive subgrades

This study evaluates the performance of model pavements constructed in a 1.5 m × 1.5 m × 1.1 m test chamber under differential swell pressure induced by expansive subgrades. Three configurations were tested− one with a 400 mm Wet Mix Macadam (WMM) layer directly over the subgrade, another with a 400 mm WMM layer over a 250 mm prepared subgrade, and a third with a 400 mm WMM layer over a 500 mm prepared subgrade. Differential swell pressure was simulated using a 250 mm dia. plate, resulting in subgrade rise of 12.5 mm, reported as potential vertical rise (PVR) in the unreinforced scenario. The same pressure was applied to reinforced scenarios, where geogrid and geotextile reinforcements with tensile strengths of 100 kN/m and 200 kN/m were placed at the subgrade level to mitigate swell-induced heave. Geotextile reinforcement reduced PVR by 85%, 78%, and 58% under swell pressures of 150 kPa, 225 kPa, and 425 kPa, respectively; while geogrid reinforcement achieved reductions of 77%, 68%, and 36% under the same pressures. Both reinforcements minimized swell pressure transfer to pavement layers, enhancing stability and improving the pavement performance. The findings demonstrated the effectiveness of geogrid and geotextile reinforcements in significantly mitigating heave under expansive subgrade conditions.