Engineering Assessment of South-Eastern Niger Delta Soils Utilized for Highway Pavement

Abstract

Engineering properties of soils recovered along a road alignment route (right-of-way) and borrow pits of a 30 km road in the South-Eastern Niger Delta area, Nigeria were assessed for utilization as highway pavement earth materials. Laboratory soil tests conducted included the natural moisture content, grain size distribution analysis, consistency limits, standard proctor compaction and California bearing ratio (CBR). About thirty-five (35) soil samples were retrieved from the fifteen (15) boreholes and examined. Results show that all identified and examined soil samples from the borings along the road route and the borrow pits classified as A- 3, A-2-4 and A-2-6 are excellent sub-grade, good fill and sub-base materials. However, none of the soil types meet the engineering requirements for use as base course. Earth materials comprising overburden of clayey sands, silty sands and sandfills (previously used as sub-grades) along the Ahoada-Upatabo-Oyigba-Ebiriba-Ombor 30 km. road in South-eastern Niger Delta were evaluated for highway pavement construction. The results are presented in this paper. The objective of the study was to examine the appropriateness of these soils for the purpose of pavement design and construction as sub-grades, sub-base and base course materials. Previous related studies in the area include works by (1-5).