APPLICATION OF ELECTRICAL RESISTIVITY TOMOGRAPHY IN INVESTIGATING CAUSES OF ROAD FAILURE: A CASE STUDY AT FUPRE CAMPUS

Road pavement failure significantly impacts the structural integrity and service life of road networks worldwide, making it essential to understand its underlying causes for effective remediation and long-term stability. Electrical resistivity surveys have emerged as a valuable geophysical tool for investigating subsurface conditions that contribute to road failure. This non-invasive method detects variations in subsurface resistivity, which correlate with materials such as clay, sand, rock, or voids that influence pavement performance. This study explores the application of electrical resistivity surveys, specifically using the Wenner array configuration, to identify the causes of pavement failure. The findings highlight distinct resistivity zones, with low resistivity areas (158–204 Ωm) at a depth of 2.5 m, often linked to clay-rich soils that retain water, causing swelling, shrinking, and reduced load-bearing capacity. These areas, extending from 60–90 m along the traverse, coincide with regions of severe pavement failure, as clay’s tendency to swell when wet and shrink when dry creates instability under traffic loads. Beneath this layer lies a moderate resistivity zone (367–504 Ωm) at depths between 2.5 m and 5.5 m, interpreted as weathered granite, while deeper layers show high resistivity (808–1514 Ωm) at depths of 5.5 m to 25 m, likely representing dry, compact material or rock. The study underscores that clay-dominated topsoil in low resistivity areas is a primary factor in road degradation due to its low shear strength and high compressibility, necessitating targeted engineering solutions to ensure sustainable road design.