Assessment of Structural Integrity of Reinforced Concrete Bridges Along the Lagos-Ibadan Expressway

The deterioration of reinforced concrete bridges along major Nigerian highways has raised growing concerns about public safety and infrastructure sustainability. This study assesses the structural integrity of selected bridges along the Lagos-Ibadan Expressway in the South West geopolitical zone, focusing on visible distress indicators such as spalling, cracking, corrosion of reinforcement, and carbonation depth. The research adopts a combined visual inspection protocol and non-destructive testing approach, using rebound hammer tests and cover meter readings on five bridge structures constructed between 1975 and 1995. Data collection followed the guidelines of BS EN 1504 and the Nigerian Highway Bridge Design Code. Findings reveal that over sixty percent of the assessed structures exhibit moderate to severe reinforcement corrosion, with chloride-induced deterioration identified as the dominant degradation mechanism. Carbonation depths exceeded acceptable thresholds in three of the five bridges, suggesting compromised concrete cover and long-term structural vulnerability. Maintenance records obtained from the Federal Roads Maintenance Agency indicate that routine inspection intervals have been inconsistent, contributing to delayed intervention. The study recommends a risk-prioritised maintenance schedule, adoption of cathodic protection systems for the most vulnerable structures, and integration of digital inspection logs into national bridge management systems. Results contribute to the growing body of evidence supporting proactive rather than reactive maintenance policies for critical highway infrastructure in Nigeria. Keywords: reinforced concrete, bridge integrity, non-destructive testing, corrosion, Lagos-Ibadan Expressway.