Strain Response of Hot-Mix Asphalt Overlays for Bottom-Up Reflective Cracking

TL;DR

This study uses finite element modeling to analyze how various design and environmental factors influence strain development in asphalt overlays, aiming to predict and prevent bottom-up reflective cracking.

Contribution

It introduces a comprehensive FE modeling approach incorporating viscoelastic properties and environmental effects to evaluate strain evolution in asphalt overlays.

Findings

Higher vehicle speed and subgrade/modulus increase strain rates.

Thicker overlays lead to greater horizontal strain accumulation.

Negative pavement temperatures accelerate strain increase.

Abstract

This paper examines the strain response of typical HMA overlays above jointed PCC slabs prone to bottom-up reflective cracking. The occurrence of reflective cracking under the combined effect of traffic and environmental loading significantly reduces the design life of the HMA overlays and can lead to its premature failure. In this context, viscoelastic material properties combined with cyclic vehicle loadings and pavement temperature distribution were implemented in a series of FE models in order to study the evolution of horizontal tensile and shear strains at the bottom of the HMA overlay. The effect of several design parameters, such as subbase and subgrade moduli, vehicle speed, overlay thickness, and temperature condition, on the horizontal and shear strain response was investigated. Results obtained show that the rate of horizontal and shear strain increase at the bottom of the HMA overlay drop with higher vehicle speed, higher subgrade modulus, and higher subbase modulus. Moreover, the rate of horizontal strain accumulation increases with higher overlay thickness. Although initial strain values were higher at positive pavement temperature distributions, the corresponding rate of strain increase were higher at negative pavement temperatures. Finally, an extrapolation of the strain history curve for various pavement design parameters was used to estimate the number of cycles for bottom-up crack initiation.