A Mechanistic Analysis of Static and Repeated Loading Effects on Rubberized Asphalt

Abstract

A mechanistic analysis of the behaviour of rubberized asphalt under static and repeated wheel loading is investigated. The analysis is analytically simulated using the KENLAYER computer program. Emphasis is placed on the stress and strain behaviour of rubberized asphalt versus that of non-rubberized asphalt. The study also included a damage analysis from which the design life (DL) of an asphalt pavement was determined. From the damage analysis, the number of load repetitions (LR) on a given pavement arrangement was determined and compared in both cases of rubberized and non-rubberized asphalt. Pavement systems studied, whether rubberized or non-rubberized, comprised three layers, top, grade, and subgrade. Different layers were represented by different moduli of elasticity and Poisson's ratios. Only the properties of the top and the grade layers were changed when rubberized asphalt was used. The subgrade was neither rubberized nor affected by the addition of rubber to the top and the grade layers. The study involved a one-season year and a four-season year to examine the effect of temperature variation on the stress and strain behaviours of asphalt pavements.

In both rubberized and non-rubberized cases, dual wheel load results in greater vertical displacement, greater vertical stress at failure, less vertical stress due to static loads, lower allowable number of LR, and lower DL. For single or dual wheel loading, the effects of adding rubber are greater vertical displacement, less vertical stress at failure, more vertical stress due to static loads, lower allowable number of LR, and lower DL. To increase the accuracy of the results, it is recommended that the year be divided into 12 periods representing each month with its own temperature conditions.

Keywords:

• Rubberized asphalt
• Pavement
• KENLAYER
• Modulus of elasticity

Acknowledgements

The author wishes to acknowledge the effort of Mr. Gregory M. Oswitt for running the test cases of this analysis. The financial support provided by the Potter Foundation and Union College is greatly appreciated.