Behavior of Geogrid- and Geocell-Stabilized Unpaved Pavements Overlying Different Subgrade Conditions Under Monotonic Loading

In this study, four geogrids made of polypropylene (PP) and polyester (PET) with varying sizes of aperture were used to investigate the influence of material type (PP and PET) and tensile strength (varying from 30 to 60 kN/m) of geogrid on the mechanical behavior of the stabilized pavements. In addition, four geocells made of high-density polyethylene (HDPE) of varying heights equal to 75 mm, 100 mm, 150 mm, and 200 mm were used to evaluate the effect of cell height on the mechanical behavior of geocell-stabilized bases. The pavement sections built in a large-size test chamber of dimensions equal to 1.5 m × 1.5 m × 1.0 m were loaded via a 300 mm-diameter plate through an actuator. The unstabilized and stabilized pavements were instrumented with displacement transducers, earth pressure cells, and strain gauges to measure and quantify the surface settlement profiles of model pavements, contact pressures at subgrade level, and circumferential strains mobilized on the walls of the geocells, respectively. Besides, analytical formulation for load spread angles was proposed for geogrid and geocell-stabilized pavements under applied loads. The strains mobilized in the geocells showed a linear variation along the width. However, strains measured along the cell height showed higher values at the bottom than those near the middle and top of the cell, which suggested non-uniform confinement of aggregate particles within the geocell pocket. The stress levels at the subgrade level reduced up to 61% for geogrids and 78% for geocells. The load spread angles of control sections overlying different subgrades conditions (California bearing ratio (CBR) = 1%, 3%, and 5%) ranged between 23° and 43°. For the same test conditions, load spread angles for sections with geogrid- and geocell-stabilized bases were found to be higher ranging between 29° and 53°, and 30° and 55°, respectively. Additionally, superior performance of stabilized bases was observed for a stiffer geogrid and higher height of geocells with relatively high peel strength.