Evaluating the Potential for Hot Mix Asphalt Rutting Performance Using Laboratory and Digital Imaging Technique

ABSTRACT The objective of this study is to evaluate the non-structural rutting resistance of six typical Superpave™ mixes used in Ontario for surface course using conventional and advanced methods. Hamburg Wheel Rut Tester (HWRT), Dynamic modulus test, and Digital Imaging Processing (DIP) technique were used in the evaluation. These mixes include two Superpave SP12.5 and four SP12.5 FC2 mixes. Six Superpave Performance Grading (PG) binders and three traffic levels were used in the design of these mixes. The effect of aggregate type and binder type in improving the rutting resistance was investigated. Manual method was used to quantify the shear upheave for all mixes. The common devices in measuring Hot Mix Asphalt (HMA) rutting ignore the effect of shear flow and only measure the effect of densification which might affect the ranking of mixes according to rutting susceptibility. DIP was used for further analysis of aggregate effect on HMA rutting resistance. This included estimating aggregate contacts, segregation and orientation of two dimensional cross section images after loading. This method provides internal structural analysis of HMA in order to understand the failure mechanism in rutting and its relationship with each individual component characteristics. Dynamic modulus test was also conducted to investigate the correlation between the HMA stiffness and rutting. It was found that Dynamic modulus |E*| is very effective for evaluating the resistance of HMA mixtures against rutting due to the strong correlation. The results of this study also showed that DIP provides an indication of HMA rutting potential. Aggregate contacts showed a good correlation with mixture rutting resistance measured manually and by using HWRT. Overall, imaging analysis would assist in the design of long lasting pavement

Safety and Economic Benefits of Partially Paved

ABSTRACT The main function of partially paved shoulders (PPSs) is to improve safety and reduce maintenance. As well, any tendency to edge cracking is moved from the travel lane to the partially paved shoulder, thereby extending pavement life. Safety is improved by minimizing pavement edge drop off and reducing granular maintenance. Property damage is also reduced and driver comfort increases because of a perceived increase in road width. This paper is based on a study of 180 PPS sections, and is directed toward quantifying the safety and economic benefits. Motivation for the study came from a climate of economic restrictions and the associated need to quantify any benefits of PPS's. Survey and evaluation procedures are described in the paper, as is the innovative life-cycle cost approach. Based on the survey, the majority of people did not feel that gravel shoulders were safe and found them to be a dramatic exit from the roadway. Gravel fly up was identified to be a major concern and 80% of those surveyed had experienced broken or cracked windshields while 73% had experienced paint chips and 8% had encountered broken headlights due to gravel fly up. The results show that PPS's have definite safety benefits; moreover, granular PPS's had a significantly longer service life than earth PPS's. Performance equations and life-cycle costs which quantify these results are provided. Finally the paper presents conclusions and recommendations toward those situations where partially paved shoulders are warranted for safety and economic reasons

TEMPERATURE AND AGING EFFECTS ON TIRE/PAVEMENT NOISE GENERATION IN ONTARIAN ROAD PAVEMENTS Professor, Canada Research Chair in Sustainable Pavement and Infrastructure Management

ABSTRACT 2 Tire/pavement noise is caused by a complex set of interactions in the contact patch. 3 Managing pavement surfaces and materials has been an effective strategy for noise 4 mitigation, because it is often possible to act at the source of the noise. Since traffic noise is a 5 public concern, due to the effects on heath and the economy of a country, it is crucial to 6 understand the acoustic performance of road pavements through continuous monitoring, 7 because their acoustic properties may diminish over the time. Overall, the results show that sound intensity and sound pressure level raise when the 18 age increases, while temperature performs a minor influence. Also, the results demonstrate 19 that sound intensity and sound pressure levels have a significant variation depending on the 20 type of pavement. Finally, good correlation between CPX and OBSI methods was observed