Full-scale field studies on performance evaluation of geogrid reinforced flexible pavements through cyclic plate load tests

Abstract

To address the growing demand for mechanistic and performance-based inputs in pavement design, field-scale cyclic plate load tests were conducted to investigate the effect of subgrade strength, expressed as the California Bearing Ratio (CBR), on the structural behaviour of geogrid-reinforced flexible pavements. For this purpose, CBRs of 6%, 8%, 10%, and 15% were considered with three different geogrids, namely PP30 (polypropylene), PET60, and PET80 (polyester) geogrids. The reinforcement benefit quantifiers were evaluated in terms of the Traffic Benefit Ratio (TBR), Modulus Improvement Factor (MIF) and Layer Coefficient Ratio (LCR). The findings revealed a clear inverse relationship between subgrade CBR and reinforcement benefit, with the maximum TBR of 3.3 observed at a CBR of 6%, and the lowest TBR of 1.5 at a CBR of 15%. PET80 performed comparatively better than other geogrids in all subgrade conditions. Additionally, an optimized pavement section was tested over the 15% CBR subgrade to evaluate design optimization. The comparable performance metrics (TBR = 1.75, MIF = 1.54, LCR = 1.19) demonstrated the feasibility of achieving significant material savings without compromising structural capacity. The overall findings confirm that geogrid reinforcement is most effective in low-CBR soils, while at the higher subgrade strengths, TBR gains are minimal. © 2026 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.