Daramola et al. Geo-Engineering (2018) 9:28 https://doi.org/10.1186/s40703-018-0096-9 TECHNICAL NOTE Open Access Premature failure of a major highway in southwestern Nigeria: the case of Ipele–Isua highway S. O. Daramola*, S. Malomo and Y. A. Asiwaju‑Bello *Correspondence:
[email protected] Abstract Department of Applied Mineralogical, geochemical and geotechnical analyses were carried out to evaluate Geology, Federal University of Technology, Akure, Nigeria the contributions of geological and geotechnical properties of subgrade soils to the incidence of failure of the Ipele–Isua road, south-western Nigeria. Field observations showed that the road is in a very poor state of disrepair as major portions of the road alignment have failed. The road alignment is underlain in places by Quartz Schist, Banded Gneiss and Granite Gneiss. The results of the laboratory tests revealed that the natural moisture content ranges from 6.5 to 23.3%, liquid limit from 20.1 to 55.1%, plasticity index 5.2 to 22.2%. The grain size analysis showed that the amount of fnes ranges from 13 to 60.8%. Others are linear shrinkage between 2.9 and 11%, free swell between 16.67 and 41.94%, maximum dry density from 1520 to 1792.1 kg/m3 and CBR between− 2 and 17%. The specifc gravity ranges from 2.51 to 2.63. The major clay minerals present are kaolinite and dickite with dominance in 50% of the samples. Major oxides present are SiO2, Al2O3, Fe2O3, K2O. Na2O, MgO and CaO are generally less than 1%. Based on AASHTO classifcation, 19% of the samples are classifed as A-2-4, 33% classifed as A-2-6 while 44% classifed as A-7.