Finite Element Model for Rutting Prediction of Flexible Pavement with Cementitiously Stabilized Base-Subbase

Cementitiously stabilized materials (cement-stabilized base-subbase, lime-fly ash stabilized subgrade, etc.) are widely used in roadway pavements by state agencies. Their use is a cost-efficient and environmentally friendly way to recycle industrial by-products. In the current Mechanistic-Empirical Pavement Design Guide developed under NCHRP Project 1-37A, cementitiously stabilized layers are assumed not to contribute to the total permanent deformation of the pavement. Such an assumption may lead to a design for an inadequate base thickness, especially when a thin asphalt concrete layer or pavements subject to heavy traffic loading are used. In this study, a unified permanent deformation model developed for various pavement materials was used to simulate the permanent deformation behavior of cementitiously stabilized materials in flexible pavements. The proposed model was implemented into the ABAQUS program through a UMAT subroutine. The finite element (FE) model was calibrated by analyzing the permanent deformation results from six accelerated pavement test sections. A shift factor of 1.13 was obtained to account for the condition differences between the laboratory permanent deformation test and the field. The FE model and the calibrated shift factor were then used to predict the rut depths of two selected low-volume roads. Good agreement was found between the predicted and measured data.