A Comparative Analysis of Reinforced Flexible Pavement Performance over Various Subgrades

The performance of flexible pavements depends greatly on the strength and behavior of the underlying subgrade. Weak subgrades lead to early distress, higher maintenance costs, and increased life-cycle expenses. This study compares the behaviour of pavements constructed on clay, silt, sand, and laterite subgrades under reinforced and unreinforced conditions, with the aim of assessing how reinforcement improves strength, deformation characteristics, and overall performance. Laboratory investigations included index properties, Proctor compaction, CBR, UCS, settlement measurements, and rutting tests. Each soil was evaluated first in its natural state and then with geogrids, geotextiles, and natural fibers, chosen for their availability and cost- effectiveness. Reinforcement significantly improved engineering properties across all soils. CBR values increased notably—over 100% in clay—while UCS values nearly doubled, especially in fine-grained soils. Reinforced samples also exhibited lower settlements and reduced rut depths, resulting from improved stress distribution and restricted lateral soil movement. Among the materials tested, geogrids provided the highest improvement, followed by geotextiles and natural fibers. The study also indicates the potential to reduce pavement thickness without compromising performance, lowering material and construction costs. Overall, the findings confirm that soil reinforcement enhances pavement durability, promotes sustainable design, and offers practical benefits for regions with weak subgrade conditions.