In recent years, two types of test methods have emerged to evaluate the susceptibility of asphalt mixtures to cracking at intermediate temperatures as part of performance-related mix design specifications: the indirect tensile (IDT) test and the semi-circular bending (SCB) test. In parallel, several associated analysis approaches have been utilised to evaluate cracking characteristics of these mixtures. The objective of this paper was to evaluate various cracking indices obtained from IDT and SCB tests in terms of their ability to provide a low-variability and high-discrimination response. In addition, the ranking potential of the considered indices in terms of cracking performance of asphalt mixtures was evaluated and inter-correlated. The cracking indices were able to capture the asphalt mixture performance with the fracture strain tolerance (FST) index and cracking resistance index (CRI) showing better performance when compared to other cracking indices. Generally, the IDT test results better distinguished the cracking performance of asphalt mixtures when compared to the SCB test results. The Ideal-CT index (CT_index) from the IDT test and the flexibility index (FI) from the SCB test demonstrated a fair correlation. Overall, the results demonstrated the suitability of both tests for predicting the cracking performance of asphalt mixtures at intermediate temperatures.

In this study, soft computing and multilinear regression techniques were employed to develop models for prediction of progression of chip seal percent embedment depth ( P_e). The model uses inputs such as cumulative equivalent traffic volume, Vialit test results, dust content of aggregates, and initial embedment depth. Multilinear regression, adaptive neuro-fuzzy system, and artificial neural network techniques were used to estimate the P_e. The contribution of the variables affecting P_e was evaluated through a sensitivity analysis. The results indicate that while most of the proposed models were able to predict the P_e reasonably, the artificial neural network model performed the best.

The repeated load permanent deformation (RLPD) test is recognized as the most appropriate laboratory procedure to characterize rutting in asphalt mixtures. It is currently used in support of the calibration of the rutting model of the Mechanistic-Empirical Pavement Design Guide (MEPDG). However, certain aspects of the RLPD test conditions, method of analysis of the test results, and calibration process are not well defined. The primary objective of this study was to provide an overview of the testing and calibration variables and quantify their effects on the asphalt concrete rutting prediction using the AASHTOWare Pavement ME software. Two hot mix asphalt and two warm mix asphalt were characterized in the laboratory by performing confined and unconfined dynamic modulus tests and RLPD tests at a single temperature. RLPD data for two additional temperatures were obtained mathematically using the dynamic modulus shift factors (from both confined and unconfined conditions). Different scenarios were analyzed by considering the effect of (1) using confined and unconfined dynamic modulus test results to calculate resilient strains, (2) shifting RLPD data, (3) using single or multiple RLPD temperatures, and (4) using confined and unconfined |E^*| as an input of the AASHTOWare Pavement ME. Depending on the case considered, differences in the results ranged between 0% and 80% when different methods of analyses were used. The impact of the type of asphalt concrete on rutting prediction seems to be nonnegligible as the two warm mix asphalts show a wider variability than the two hot mix asphalts.

The objective of this study was to explore the use of monotonic loading tests (“monotonic tests”) as screening tools to assess the rutting potential of dense-graded asphalt surface mixtures in Virginia. To that end, three monotonic tests—the indirect tensile at high temperature (IDT-HT) test, the rapid rutting (RR) test, and the Marshall stability and flow (MS) test—identified from the literature, were evaluated using 16 plant-produced asphalt mixtures with “A” and “D” designations. The scope of the work also included performing the multiple stress creep and recovery test on the extracted and recovered binders. The results were applied to assess the monotonic tests and the asphalt pavement analyzer (APA) test relative to each other using several performance metrics. The results were also employed to develop performance threshold criteria for the tests being considered. The results showed that the IDT-HT and RR tests can be used to screen the rutting potential of asphalt mixtures meeting the Virginia Department of Transportation (VDOT) mixture volumetric and gradation requirements for A and D mixtures. The initial performance criteria for the IDT-HT and RR tests were established for these mixtures. Based on the results, the IDT-HT test was found to be the most suitable alternative test to the APA test.