IMPACT OF SUBGRADE SOIL VARIABILITY AND TRAFFIC LOADING ON FLEXIBLE PAVEMENT PERFORMANCE IN NIGERIA

Summary

Subgrade soil properties critically influence the performance of flexible pavements. This study evaluates subgrade variability and its implications for pavement durability in Nigeria, using soil samples collected at depths of 3 m, 6 m, and 9 m from Akazi sand beach in Ihiala, Anambra State. Laboratory tests including sieve analysis, Atterberg limits, specific gravity, compaction, and California Bearing Ratio (CBR) were conducted to assess soil suitability. Results indicate that shallow layers (3 m and 6 m) comprise fine-grained, low-density soils with low CBR and moderate plasticity, rendering them susceptible to deformation and rutting under traffic loads. Deeper layers (9 m) exhibit higher density and improved load-bearing capacity but require elevated moisture content for optimal compaction. Significant variability in subgrade properties underscores the need for targeted interventions. Recommended measures include stabilization with lime or cement, controlled compaction, efficient drainage, traffic management during construction, and ongoing monitoring. Implementing these strategies is expected to enhance pavement resilience, reduce maintenance costs, improve traffic safety, and extend the service life of flexible pavements in regions with heterogeneous subgrade soils.

Index Terms

Browse additional articles authored by one or more contributors to this paper.