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Impact of Seasonal Flooding on Flexible Pavement Performance in Southwestern Nigeria
(2025-07-26) Oyewo Seun Temiloluwa
Seasonal flooding significantly undermines the performance and longevity of flexible pavements in Southwestern Nigeria, where intense rainfall, poor drainage, and weak subgrade materials exacerbate pavement deterioration. This study investigates the effects of flood events on pavement structures through field surveys, deflection testing, and geotechnical analyses in Lagos, Oyo, and Ogun States. The research identifies key distress mechanisms such as rutting, cracking, and subgrade softening caused by prolonged water exposure, confirming that flood duration and intensity directly correlate with decreased structural integrity. Laboratory tests reveal that post flood California Bearing Ratio (CBR) values declined by up to 45%, while Falling Weight Deflectometer (FWD) deflections increased by 30%, signaling substantial strength loss. A multivariate regression model was developed to predict Pavement Condition Index (PCI) based on flood variables, achieving a strong correlation (R² = 0.87). The study also evaluates economic impacts, estimating that flood damaged roads incur 40–50% higher rehabilitation costs. Mitigation strategies, including enhanced drainage design and use of resilient materials, are recommended. Findings support the need for policy reforms and adaptive pavement design to improve infrastructure resilience in flood prone areas of Nigeria.
Engıneerıng and Polıcy Solutıons for Pavement Faılures on Nıgerıan Hıghways
(2025-09-12) Oyewo Seun Temiloluwa
Pavement failures on Nigerian federal and state highways are a critical infrastructure challenge, adversely impacting the economy, environment, and public safety. This paper investigates the primary causes of these failures, such as substandard materials, design deficiencies, overloading, drainage issues, and poor maintenance. Through analytical evaluation, field data, and case studies, the article explores the multifaceted consequences of pavement deterioration, including increased transport costs, road accidents, and environmental degradation. Engineering solutions are proposed, focusing on material optimization, sustainable construction practices, effective drainage systems, and routine maintenance. Notably, the study advocates for the integration of recycled and locally available materials, including cement kiln dust and polymer wastes, to improve performance while minimizing costs. The paper concludes with actionable recommendations and research directions, aimed at guiding policymakers, engineers, and stakeholders toward sustainable highway infrastructure in Nigeria.
ASSESSMENT OF HEAVY METAL CONTAMINATION AND SELF-CLEANSING CAPACITY OF THE OSUN RIVER, SOUTHWESTERN NIGERIA
(2025-03) Oyewo Seun Temiloluwa
The Osun River, a vital water resource in Southwestern Nigeria and a cultural landmark, faces increasing pollution pressure from urbanization and industrial activities. This study assesses its current water quality and self cleansing capacity by analyzing spatial variations in physicochemical parameters and heavy metal concentrations. Water samples were collected from five locations along the river's course during the dry season and analyzed using standard methods, including Atomic Absorption Spectrophotometry (AAS). Results indicated that heavy metals typically associated with intensive mining (Cd, Cr, Co, Pb, Cu, Ni) were below detectable limits. However, iron (Fe) concentrations (0.38 - 2.82 mg/L) consistently exceeded the World Health Organization (0.3 mg/L) and Nigerian (0.3 mg/L) standards across all but the most downstream site. A clear downstream trend of decreasing turbidity, iron, and zinc concentrations was observed, demonstrating the river's natural self-purification capacity. Despite this, high turbidity levels (up to 53.51 NTU) in urban stretches indicate significant organic and particulate pollution. The study concludes that while the Osun River retains a measurable self-cleansing ability, it is contaminated with Fe and suspended solids, necessitating improved wastewater management and continuous monitoring to safeguard public and ecosystem health in line with SDG 6 targets.
EFFECT OF MAIZE POD ASH AS STABILISATION OF SUBGRADE SOIL
(2025-04) Oyewo Seun Temiloluwa
This study focused on effect of Maize Pod Ash (MPA) as stabilisation of subgrade soil and MPA have been found to be promising stabiliser due to its pozzolanic properties. The soil sample was obtained from a borrow pit located at Orita Ara, Ede–Iwo road in Osun State, South Western Nigeria. Maize pod was obtained from maize vendors in Ifon, a rural community in South Western Nigeria. It was dried in the sun to eliminate moisture and was later ground and took to furnace at 650oC temperature to obtain the MPA. Laboratory tests carried out on the soil sample and MPA include X–Ray Fluorescence (XRF), particle size analysis, and the soil stabilisation with 0%, 4%, 8%, 12% and 16% MPA using Atterberg limit, compaction, and California Bearing Ratio (CBR) tests. Chemical analysis using XRF test revealed that MPA is class F pozzolan while the soil was classified as A–2–7(4) according to American Association of State Highway Transportation Official. The compaction test showed that as the percentage of MPA increases, the Maximum Dry Density (MDD) decreases and the Optimum Moisture Content (OMC) increases with the highest MDD (23.2 kN/m3) and lowest OMC (11 %) observed at 8% MPA. It was also observed that 8% MPA have the highest CBR value of 12.94 % compared with the soil sample with 1.40 %. This observation showed that the MPA can upgrade the geotechnical properties of subgrade soil.
Compressive and Tensile Strength Performance of Chicken Feather Reinforced Concrete Incorporating Milled Palm-Kernel Shell as Partial Replacement for Fine Aggregate
(2025-12) Oyewo Seun Temiloluwa
Environmental pollution is presently a global scourge. The incorporation of waste materials in concrete production does not only turn waste into wealth but also proffer solution to pollution of all kind. This study evaluates the compressive and tensile strength properties of chicken feather fibre (CFF) reinforced concrete containing Milled Palm Kernel Shell (MPKS) as fine aggregate partial replacement. Chicken feather and MPKS were obtained and processed. Samples of concrete were cast by varying the percentage of the CFF which ranges from 0.25% to 1.25% at an interval of 0.25% with constant addition of 10% MPKS as fine aggregate replacement. Slump test was conducted on the fresh concrete samples, compressive strength and splitting tensile strength tests were also conducted on the hardened concrete. The results show that the gradation curve and specific gravity for both sand and MPKS satisfy the standard specification. Both the compressive strength and splitting tensile strength decreases with the increase in the fibre percentage. Sample with 0% CFF fibre content has the highest values of 36 N/mm2 and 3.2 N/mm2 for compressive and splitting tensile strength respectively. However, sample A1 with 0.25% CFF inclusion and 10% FKPMS display good compressive and splitting tensile strength of 32 N/mm2 and 3.0 N/mm2 respectively, which meet the target standard strength of M25 concrete. This shows that both CFF and FMPKS can be judiciously utilized in green concrete production, thereby turning waste into wealth.