The Benkelman Beam is a widely used, portable device in civil engineering for evaluating the structural integrity of flexible pavements (such as asphalt roads) by measuring deflection under simulated traffic loads. Developed in the 1950s during the Western Association of State Highway Organizations (WASHO) Road Test, it operates on a simple lever-arm principle to quantify how much the pavement rebounds after a load is applied and removed. This helps assess pavement strength, identify weak spots, and inform maintenance or rehabilitation decisions.

PURPOSE

• Primary Use: Measures rebound deflection of pavement surfaces under a standard wheel load (typically from a heavy vehicle like a truck) and tire pressure. This deflection data indicates the pavement’s load-bearing capacity and potential for fatigue cracking or rutting.
• Applications: Non-destructive testing for roads, highways, and airport runways. It’s cost-effective for field surveys but is labor-intensive compared to modern automated devices like Falling Weight Deflectometers (FWD).
• Limitations: Provides only a single-point deflection measurement (not a full deflection basin) and requires manual operation, making it slower for large-scale testing.