This report, requested to provide guidance in identifying appropriate methods to analyze the performance of hot mix asphalt (HMA) mixture properties and to determine performance potential, is provided for contractors and state agencies as a temporary guideline for assessing good mix performance. The purpose of this project is to evaluate available information on permanent deformation, fatigue cracking, low temperature cracking, moisture susceptibility, and friction properties, and as appropriate recommend performance tests that can be adopted immediately to ensure improved performance. Emphasis is placed on permanent deformation.

Performance testing for hot-mix asphalt

Asphalt concrete (AC) is a strongly heterogeneous material that consists of asphalt cement, voids, fine particles, sand, and coarse aggregates A review of the literature reveals that the investigations of AC have mainly concentrated on the macroscopic behavior of the material based on the assumption that the mixture is homogeneous This assumption is mainly due to the extreme difficulty associated with the quantitative measurements of AC microstructure and the random nature of the aggregate distribution This paper applies an innovative digital image-processing technique to quantify the distribution, orientation, and shape of coarse aggregates (greater than or equal to 2 mm) in AC mixtures Results of the quantitative measurements of coarse aggregate distribution and shape in AC mixture are then presented and analyzed The quantitative results of AC microstructure clearly indicate the following findings: (a) the microstructure characteristics of coarse aggregates in AC mixtures can be accurately measured using the digital image-processing technique; (b) the area gradation of aggregate cross sections by the Feret diameter gives an excellent prediction of the sieve gradation of coarse aggregates (greater than or equal to 2 mm) used in the design of AC mixtures; (c) the major cross sections of coarse aggregate particles have the tendency to lie horizontally in the mixtures; and (d) comparison among two laboratory and two field compaction techniques provides valuable information related to compaction quality in terms of favorable aggregate distribution within the mixtures

Application of digital image processing to quantitative study of asphalt concrete microstructure

An asphalt concrete damage–energy fatigue approach based on the concept of change in dissipated energy is presented in this paper. The damage–energy based fatigue approach is simple and based on a sound theoretical background. The central concept of the energy approach is the energy fatigue curve, which is based on two key elements, namely the plateau value (PV) and the number of load cycles to true failure (Ntf). The plateau value represents the constant value of the percentage of dissipated energy that produces damage to the material under cyclic loading. Failure is defined as the number of load cycles at which this percentage of dissipated energy begins to increase rapidly, indicating instability. Flexural fatigue testing was used to test hundreds of asphalt concrete beams, mainly under controlled-strain testing conditions. It was found that PV is highly dependent on the initial loading conditions, stress, strain, and dissipated energy. As a result, it can be used conveniently in pavement design. The n...

Fatigue damage analysis in asphalt concrete mixtures using the dissipated energy approach

Dissipated energy concepts for hma performance: fatigue and healing

An accurate fatigue transfer function is the critical link in M-E flexible pavement design The model relates the conditions of the pavement structure to the expected performance or life of the pavement The conclusions of this research, including the developed methodology and transfer functions, are presented below Following the conclusions, a few recommendations on testing procedure and data collection for future testing cycles are presented Further, this component of M-E design is probably the most deficient; thus, it warrants further attention and improvements The recommendations based on this study for additional improvements and research are also given

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Methodology and Calibration of Fatigue Transfer Functions for Mechanistic Empirical Flexible Pavement Design

This report evaluates test procedures for measuring the fatigue response of asphalt paving mixtures, and summarizes current knowledge of the factors that influence fatigue response. Available test methods are classified, and criteria used to evaluate each method for its potential use as a laboratory standard are discussed. The 3 most promising methods are considered to be simple flexure, diametral fatigue, and tests based on fracture mechanics principles. Factors affecting fatigue repsonse include specimen fabrication, mode of laoding, mixture variables, and loading and environmental variables. Mode of loading, typically either controlled-stress or controlled-strain for laboratory testing, is one of the primary factors affecting fatigue response. Air void content and temperature, both affecting mixture stiffness, may have more significant influence on fatigue repsonse than any other variable. Many mixture, load, and environmental factors also influence fatigue respose and must be considered both in the development of test protocols and in the determination of asphalt and mixture properties that are essential for fatigue-resistant pavements.

J Craus

Papers

Summary report on fatigue response of asphalt mixtures