Evaluating the performance of inverted pavement structure using the accelerated pavement test (APT)

Abstract

• Full-scale inverted pavement was investigated. • Accelerated pavement test was applied to the inverted pavement. • Rutting performance between inverted and conventional pavements was compared. • Inverted pavement structure outperformed the conventional flexible pavement. Inverted pavement is considered an unconventional type of flexible pavement structure. In this pavement structure, an unbound aggregate base (UAB) with a low initial modulus is sandwiched (layered) between two stiffer layers, a thinner asphalt concrete layer (AC) and a cement-treated base layer (CTB). This paper presents a comparison study of the rutting performance (permanent deformation) between conventional and inverted pavement structures. In addition, the inverted pavements with different thicknesses of UAB and CTB were studied. The accelerated pavement test (APT) method was conducted on a full-scale pavement consisting of two inverted pavement lanes and one typical three-layer conventional flexible pavement lane as the control section for performance comparison. Significant permanent deformation was observed in all three pavement lanes after the completion of 100,000 passes of APT. Comparisons of the measured total deformations showed that the inverted pavement structure outperformed the conventional pavement. Furthermore, the inverted pavement with a thicker CTB layer exhibited less deformation compared with the inverted pavement with a thicker UAB layer. The stiffness of the UAB layer of the inverted pavement increased with the loading passes. A stiffer UAB could provide a cushion for the thin AC layer, resulting in less deformation in the AC surface compared with that of the conventional pavement. Furthermore, the loading on the pavement surface had a larger affected area in the inverted pavement structure. Based on the overall pavement conditions, the inverted pavement can be regarded as a promising alternative to the conventional flexible pavement, and the asphalt mixture layer thickness can be reduced during the construction.