Highway pavement failure induced by poor soil geotechnical properties at a section along the F209 Okitipupa-Igbokoda highway, southwestern Nigeria

Abstract

Failure of highway pavement is a common feature on many major highways in Nigeria. Extensive field and laboratory investigations on kilometer 20 to kilometer 25 along the F209 Okitipupa– Igbokoda highway, Southwestern Nigeria, revealed that the road was deformed by the development of potholes resulting from poor physical properties of the pavement subsoil materials. Laboratory soil mechanics tests carried out on the disturbed soil samples collected from the failed sections of the road showed that the natural soil moisture ranges from 7.10% to 9.7%, liquid limit from 22% to 43.50%, linear shrinkage from 2.30 to 5.20, and the specific gravity from 2.60 to 2.66. The California bearing ratio (CBR) value was 55% showing a considerable reduction in strength as a result of surface water ingress into primary cracks that later developed into potholes. X-ray diffraction studies showed the presence of abundant kaolinite peaks and a subdued goethite peak without any trace of montmorrilonite. The presence of excess fines in the pavement construction materials (soils) contributed to the failure of the highway pavement at this locality. The low CBR value is also a noted cause of highway pavement failure. Key Words: Kaolinite, potholes, pavement failure. Ife Journal of Science Vol.6(1) 2004: 41-44