Investigation on Top-Down Cracking on Two-Lift Concrete Pavement under Freeze–Thaw Environment.

Top-down (TD) cracking is the main concrete pavement cracking type in seasonal frozen areas. A two-lift concrete (2LC) pavement, including a polypropylene fiber reinforced concrete (PFRC) top lift and a portland cement concrete (PCC) bottom lift, is proposed to mitigate TD cracking. This study conducted prenotched three-point bending beam tests (3PBBTs) in the laboratory and numerical models have been developed to evaluate the fracture characteristics of concrete materials, including PCC, PFRC, and 2LC, in a freeze–thaw (FT) environment. Based on the double- K fracture model, the fracture characteristics of concrete materials have been obtained. In the mesoscale, progressive damage constitutive models have been developed based on the Mori-Tanaka homogenization theory and three-dimensional (3D) Hashin failure criterion. Three-dimensional finite-element models have been developed to simulate the prenotched 3PBBTs with the progressive damage constitutive models coupled. It has been found in experiments that 2LC has better fracture resistance than PCC with and without FT treatments. Validated by experimental data, the developed FE models are capable of describing the fracture characteristics of concrete materials in the FT environment. Sensitivity analyses on factors that may influence the fracture resistance of 2LC have been conducted. This study validates that the proposed 2LCP has better TD cracking resistance than conventional PCC pavements and also suggests useful measurements enhancing the TD cracking resistance of 2LCP. [ABSTRACT FROM AUTHOR]