Harmonizing Flexible Pavement Rutting Design with Balanced Mix Design

Abstract

The state-of-the-practice in asphalt concrete mix design and pavement structural design are two divergent concepts. The simulative laboratory performance tests such as Hamburg Wheel Tracking (HWT) and Asphalt Pavement Analyzer (APA) that are used primarily for balanced mix design are pragmatically accelerated surrogate tests developed to ensure the stability or ranking of mixes. Pavement structural design methods, being empirical or mechanistic-empirical, do not consider these laboratory test results in their analyses, in favor of other fundamental mechanical parameters such as dynamic modulus. As such, the selection of the type of mix to be placed on a project is based on the local experience, and a set of consensus limits, rather than the demand of the pavement section. A harmonized strategy that integrates the results from mix tests with the pavement structure, material properties, environmental conditions, and traffic levels can lead to an optimized pavement system. A framework is proposed to incorporate the laboratory HWT and APA device results into the rutting analysis associated with most mechanistic-empirical structural design algorithms. The proposed framework was applied to the results from two accelerated pavement testing facilities and six in-service pavement test sections to demonstrate its feasibility. The proposed strategy can be potentially used to predict the rutting life of the pavement reasonably well. By balancing the rutting demand of an asphalt layer with the rutting capacity of a given mix, the proposed method can potentially lend itself to the use of local materials for a more economical and sustainable pavement structure.