A Structural and Economic Evaluation of Perpetual Pavements: A Canadian Perspective
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Perpetual pavement design philosophy provides a long-life pavement design alternative. The ability of a pavement design to perform as long-life pavement is subjected to several technical constraints. Throughout the past 10 years, perpetual asphalt pavement designs have been under investigation in several parts of the world. The Canadian climate represents an additional challenge to the success of long-life pavement performance. This project investigated the construction and performance of three pavement test sections that were constructed on Highway 401 in Southern Ontario. The construction phase of this project was completed in 2010. The test sections were equipped with various sensors to monitor the structural performance. The test section included two perpetual pavement sections and one conventional pavement section. The two perpetual pavement designs were identical with the exception of the bottom asphalt layer, which was constructed as a Rich Bottom Mix (RBM) layer in one of the perpetual sections. The three pavement sections were evaluated from a structural point of view through the analysis of the in-situ tensile strain collected from asphalt strain gauges installed at the bottom of asphalt layers under the wheel path. In addition, asphalt material laboratory characterization was undertaken by testing asphalt samples collected during construction of the three test sections. The laboratory testing was performed at the Centre for Pavement and Transportation Technology (CPATT) at the University of Waterloo. The laboratory experimental matrix in this research included dynamic modulus testing, resilient modulus testing and Thermal Stress Restrained Specimen Testing (TSRST). The correlation between various laboratory test results and the collected in-situ tensile strain was evaluated. Several linear regression models were developed to correlate the laboratory test results and the field asphalt temperature with the in-situ tensile strain. Overall, it was found that the perpetual pavement with RBM section had the lowest tensile strain at the bottom of asphalt layers. Also, various models were developed that predict tensile strain at the bottom of asphalt layers by using laboratory test data. An economic analysis was implemented to evaluate the perpetual and conventional pavement designs including a Life Cycle Cost Analysis (LCCA). Furthermore, a sustainability assessment for both design philosophies was executed to evaluate the environmental benefits of perpetual pavement designs. The perpetual pavement designs were shown to provide many benefits over the conventional asphalt pavement designs for usage on Canadian Provincial and Interstate Highways in similar climatic zones with similar traffic loading. The advantages of perpetual pavement design philosophy are not limited to structural benefits, but also extended to economic and environmental benefits in the long term.