Ernest Orji Akudo, Godwin Okumagbe Aigbadon, Kizito O. Musa, Muawiya Baba Aminu, Nanfa Andrew Changde and Emmanuel K. Adekunle
The purpose of this study was to investigate the likely causes of failure of some sections of road pavements in Ajaokuta, Northcentral Nigeria. This was achieved through a…
Abstract
Purpose
The purpose of this study was to investigate the likely causes of failure of some sections of road pavements in Ajaokuta, Northcentral Nigeria. This was achieved through a geotechnical assessment of subgrade soils in affected areas.
Design/methodology/approach
The methods entailed field and laboratory methods and statistical analysis. Subgrade soil samples were retrieved from a depth of 1,000 mm beneath the failed portions using a hang auger. The soils were analyzed for natural moisture content (NMC), Atterberg limit (liquid limit, plastic limit and linear shrinkage), grain size distribution, compaction and California bearing ratio (CBR), respectively.
Findings
The results of the geotechnical tests ranged from NMC (12.5%–19.4%), sand (84%–98%), fines (2%–16%), LL (16.0%–32.2%), PL (17%–27.5%), LS (2.7%–6.4%), PI (2.5%–18.4%), maximum dry density (1756 kg/m2–1961 kg/m2), optimum moisture content (13.2%–20.2%), unsoaked CBR (15.5%–30.5%) and soaked CBR (8%–22%), respectively. Pearson’s correlation coefficient performed on the variables showed that some parameters exhibited a strong positive correlation with r2 > 0.5.
Research limitations/implications
Funding was the main limitation.
Originality/value
Comparing the results with Nigerian standards for road construction, and the AASHTO classification scheme, the subgrade soils are competent and possess excellent to good properties. The soils also exhibited very low plasticity, a high percentage of sand, high CBR and low NMC, which implies that it has the strength required for road pavement subgrades. The likely causes of the failures are, therefore, due to the use of poor construction materials, technical incompetence and poor compaction of sub-base materials, respectively.
Details
Keywords
Kizito Ojochenemi Musa, Abdulbariu Ibrahim, Godwin Okumagbe Aigbadon, Ernest Orji Akudo, Obinna Akakuru, Fabian Apeh Akpah, Jacob Bolaji Jimoh, Moses Adegbola and Mu’awiya Baba Aminu
This study aims to employ an integrated approach of geology, aeromagnetic and electrical resistivity techniques to evaluate the potential causes of abortive or low groundwater…
Abstract
Purpose
This study aims to employ an integrated approach of geology, aeromagnetic and electrical resistivity techniques to evaluate the potential causes of abortive or low groundwater yield in most boreholes.
Design/methodology/approach
The process involved mapping geology and acquiring and processing aeromagnetic and vertical electrical sounding (VES) data. Oasis Montaj software was used for tasks like Reduction to the Equator (RTE), Upward Continuation (UC), Residual Magnetic Anomaly (RMA) and Euler Deconvolution (S. I = 1.0 and S. I = 2.0). VES utilized the Schlumberger array method, and field data underwent iterative analysis using Resist2Win software.
Findings
Total magnetic intensity (TMI) and RMA values range from −209.2 nT/m to 150.4 nT/m and −61.0 nT/m and 20.6 nT/m, respectively. High amplitude magnetic anomalies are observed in the northern and southwestern areas, indicating potential groundwater zones. Depth estimates for SI = 1.0 and 2.0 range from 11.1 m to 76.1 m and 16.4 m to 112.9 m, respectively, indicating varying overburden thickness and rock boundaries. Lineament reveals NE-SW and NW-SE trends, with hydro-lineament density ranging from low to very high. VES data identifies layers with resistivity and thickness values: topsoil (15.5–523.2 Om, 0.4–12.3 m), weathered basement (93.3–1655.7 Om, 19.0–54.7 m), fractured basement aquifer (242.7–9413.0 Om, 20.3–42.7 m) and fresh basement (62.8–935.3 Om).
Practical implications
Maps and conclusion generated from the study will serve as a baseline to solving completely the perennial problem of abortive and low groundwater yield.
Social implications
Insecurity and other vices suffered during the acquisition of data.
Originality/value
The geophysical data correlates with geological mapping, verifying that areas with dense hydro-lineaments like porphyritic granites and granite gneiss are promising aquifers. This suggests that groundwater presence is influenced by structural factors, offering valuable insights for future groundwater exploration in the study area.