Geotechnical evaluation of road failure: A case study of Zaria/Sokoto Road along Federal University of Gusau, Zamfara State

Pavement failure has contributed immensely to the loss of lives, disruption to normal activities, and increased amount of money being spent on maintenance annually. One of the causes is associated with inadequate investigations of subgrade materials. This current work aimed at examining the geotechnical parameters as factors of pavement failure at Zaria/Sokoto road, along Federal University Gusau. Sufficient soil samples were obtained at the failed section of the road. However, laboratory investigation such as Natural moisture content determination, Sieve analysis, Atterberg limit test, Compaction test, and California bearing ratio test by using (BSL) in order to have a better understanding of the factors causing the road failure. The result from Natural moisture content shows that the soil sample obtained contained an amount of water for each sample while sieve analysis shows that only sample B have satisfied the requirement. In addition, the Atterberg limit test indicates that only soil sample A is good for road construction while for compaction, the OMC and MDD values have also satisfied the requirements. More so, the California bearing ratio test also shows that the sub-base materials are good which makes the layers of good strength except for sample A. Unquestionably, this led to the conclusion that construction materials of the road are mostly good and excellent while some are not, and some complied to the requirements. Hence by visual observation, the drainage system of the road is very poor and the road surface is not cambered to the direction of the drainage so as to drain off water, especially during the rainy season. Water poses a lot of threat to roads which gradually creates voids and allows infiltration of water causing severe damage to the subsoil and pavement. Therefore, it is recommended that the drainage system should be properly built while cambering the road to either direction for proper running off of water.