Abstract:
Dealing with weak subgrades in road construction emerges innovative engineering resolutions to challenge their adverse
effects on construction durability, safety, and cost-efficiency. Weak subgrades contribute to pavement settlements, resulting
in frequent and costly maintenance, reduced load-bearing capacity, and safety risks. Conventional treatment methods
cause various challenges such as cost, time, and environmental concerns. This research aims to investigate the effect of
geosynthetics in improving weak subgrade performance, considering geosynthetic type and location within flexible pavement
structures. In accordance with Sri Lanka’s CIDA guidelines, which regulate a minimum subgrade 4-day-soaked California
Bearing Ratio (CBR) value of 5%, this study attempts to develop a predictive model capable of estimating the 4-day soaked
CBR value of subgrade soil while taking changes in moisture content into consideration. The research findings exhibit the
efficiency of applying geosynthetic layers at the subgrade-subbase interface in dramatic augmenting the ultimate load-bearing
capacity of weak subgrades, especially those with 4-day soaked CBR values below 5%. Geosynthetics appear as a promising,
cost-efficient, and environmentally sustainable solution to mitigate the challenges associated with weak subgrade soils in
road construction, offering the potential for enhanced construction durability, safety, and cost optimization.
