Benkelman beam delfection test

essai de déflexion

The ground is subjected to a “rolling” load

Truck loaded at 130 KN, i.e. 13 T on the rear axle
2 tires with a diameter of 25 cm – Center distance 37.5 cm – Pressure = 0.662 MPa
Benkelman beam
Measurement of deflections in hundredths of a millimeter
Number of tests per hour: up to 10

Measurement of the deflection generated by a rolling load and possibly the evaluation of the radius of curvature. The measurements can be carried out on all pavements, regardless of their nature, on the other hand the interpretation which is made of them depends essentially on the considered structure.

NF P98-200-2 link to AFNOR

Generally the elastic deflection is measured and not the maximum deflection, due to the Laboroute exemption (the truck moves forward instead of backing).

The load is not really rolling: The test can be considered static.

The test is strictly illegal: the maximum authorized load is exceeded. The rear axle, weighed alone on a scale, must reach the 130 kN reference at ± 2%. The scale should indicate a value of 13.250 t ± 0.265. This exceeds the maximum authorized load of 13t for an axle as defined in article R312-5 of the highway code.