Temperature adjustment of Surface Curvature Index from Traffic Speed Deflectometer measurements

Pavement structural condition evaluation plays an important role in assessing rehabilitation needs and making prudent investment decisions. Recently the use of Traffic Speed Deflectometer (TSD), is being considered for pavement structural evaluation especially for network level pavement management applications. Among various TSD data measurements and indices, Surface Curvature Index (SCITSD), is a widely-used index for assessing the structural condition of the AC layers. Since asphalt modulus is temperature sensitive, measured deflections and consequently the computed SCI(TSD)are also affected by pavement temperature at the time of testing. For consistent pavement evaluation, SCI(TSD)computed across sections and over time should be adjusted to a reference temperature. This study presents an applied method for adjusting SCI(TSD)to a reference temperature. The method was based on a model developed from a dataset built from responses computed with dynamic-viscoelastic analyses under TSD moving load in a wide range of pavement properties. The method was field evaluated with TSD data from three locations within the US and one location each in Europe and Australia. The results showed that the proposed method can reasonably adjust SCI(TSD)to a reference temperature which enables its application in pavement structural assessment and subsequent use in pavement management activities.