Using the Multidepth Deflectometer to Study Tire Pressure, Tire Type, and Load Effects on Pavements (1184-2)

In this study the impact of truck tire type, inflation pressure, speed, and axle load was examined by measuring depth deflections in two pavement structures (one thick, one thin) instrumented with multidepth deflectometers (MDD's). Measured depth deflections under truck loadings were converted into average vertical compressive strains in the pavement layers. The measured subgrade strains were used to estimate the time to rutting failure. Deflections measured at the bottom of the asphaltic concrete layer were used to calculate the surface curvature index which was then translated into tensile strains at the bottom of the layer. This report develops multiple linear regression models to predict the relationship between dependent variables (subgrade strain, tensile strain at the bottom of asphalt layer) and independent variables (speed, lateral offset, asphalt layer temperature, and axle load).|For the same load level, the wide based super single tires were measured to cause higher deflections, higher vertical compressive subgrade strains, and have sharper curvature to the deflection bowls than standard dual tires. Under similar loading conditions, wide based tires were predicted to be at least twice as damaging as conventional dual tires.