INVESTIGATION OF FLEXIBLE PAVEMENT RESPONSE TO TRUCK SPEED AND FWD LOAD THROUGH INSTRUMENTED PAVEMENTS

Falling weight deflectometer (FWD) and truck tests have been conducted on the Minnesota Road Research project (Mn/ROAD) in an effort to (1) study truck speed effects on flexible pavements, (2) compare pavement response under FWD and truck loads; and (3) investigate the effects of wheel path offset on the pavement response. Three flexible pavement sections were used for this study. The truck tests were performed at various speeds ranging from 10 to 103 km/h. The results showed that on a smooth pavement (IRI=0.97 m/km) strains in the bottom of the pavement continuously reduced with the truck speed. While on a relatively (relative to the smooth pavement) rough pavement (IRI=1.74 m/km), strains in the bottom of the pavement decreased as the speed of the truck increased to a speed about 65 km/h, but the strains increased when the speed was further increased from 65 km/h to 103 km/h. The effects of the pavement surface roughness were also investigated and the influence of truck suspension type was discussed.