Statistical model of pavement rutting in asphalt concrete mixes

Pavement deterioration models are important inputs for the efficient management of pavement systems, the allocation of cost responsibilities to various vehicle classes for their use of the highway system, and the design of pavement structures. The development of an empirical rutting progression model with an experimental data set from WesTrack is described. The salient features of the model specification are as follows: (a) three properties of the mix are sufficient to model the performance of the asphalt concrete pavement at WesTrack accurately; (b) the model captures the effects of the high air temperatures at WesTrack; and (c) the model predicts rut depths by adding predicted values of the increment of rut depth for each time period, which is particularly advantageous in a pavement management context. The three mix properties are a gradation index, which is obtained from the aggregate gradation; the voids filled with asphalt obtained for the construction mix in the Superpave gyratory compactor; and the initial in-place air voids. The specified model is nonlinear in the variables and the parameters and is estimated by using a random-effects specification to account for unobserved heterogeneity. The estimation results and prediction tests show that the model replicates the observed pavement behavior at WesTrack well.