No abstract

No abstract

No abstract

Asphalt mixtures contain several constituents, among which air void content has a significant effect on pavement performance. In this research, the impact of laboratory compaction air-void variations for asphalt mixtures was investigated on asphalt-mixture fracture energy and peak load, as two primary outcomes of the disk-shaped compact tension test. Two groups of asphalt mixtures with air void contents of 7 ± 1.0 % were selected, and comprehensive statistical analyses, such as Pearson’s correlation coefficient, analysis of variance (ANOVA), Welch’s test, and Tukey’s test, were conducted to explore any possible impacts of specimen-to-specimen air-void variation on fracture energy and peak load. Statistical analyses have been carried out on individual asphalt mixtures in groups and all asphalt mixtures together as a group, as well. Results showed that there is a weak-to-negligible relationship between air void, fracture energy, and peak load. In addition, results of the ANOVA at the significance level of 0.05 revealed that air void content does not have any significant effect on asphalt mixtures’ fracture energy and peak load, except for peak load data when all asphalt mixtures are grouped as single population. Finally, results of Tukey’s test demonstrated that in a range of 7 ± 1.0 %, air void does not have a significant effect on fracture energy at the significance level of 0.05. The findings of this study can help researchers and agencies extend the air-void variation tolerance to 1 % in asphalt mixtures with target of 7 % air void content to assess low temperature cracking resistance.

The purpose of this research is to provide a comprehensive evaluation of the effects of a solid pelletized plastomeric polymer on asphalt mixtures’ properties and performance with respect to different distresses. Five asphalt mixtures—a control mixture (no polymer); asphalt mixtures with 2.5%, 5.0%, and 7.5% polymer content; and a mixture with 5% polymer and lower asphalt binder content—were evaluated. The laboratory testing campaign included complex modulus, direct tension cyclic fatigue, semi-circular bending, disk-shaped compact tension, and asphalt pavement analyzer tests. Advanced performance-based simulation programs—MnPAVETM, FlexPAVETM, and ILLITC—were utilized to predict mixture performance in the context of pavement structure and local traffic and climatic conditions. In addition, four field test sections were constructed for all but the mixture with the reduced binder content and falling weight deflectometer (FWD) testing was conducted on the test sections. Based on the results of laboratory testing and performance simulation it can be concluded that the study modifier significantly improved the rutting performance and slightly improved the mixture fatigue performance. The study modifier did not show a considerable positive or negative effect on the thermal cracking performance. Based on the FWD results, solid polymer is potentially a good option to increase the stiffness of the asphalt concrete (AC) layer.