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Rapid growth of populations and extension of societies leads to the production of waste by-products, which puts a burden on landfills. To address this issue, tire derived aggregates (TDA) from scrap tires have been used as road embankments in several projects. Three different test sections using different TDA, and TDA and soil mixtures, were constructed at the Integrated Road Research Facility test road in Edmonton, Alberta, Canada. Based on falling weight deflectometer tests in different months, the fatigue life performance of the TDA embankments was evaluated against that of a conventional control section using the measured horizontal strains at the bottom of the asphalt layer and the Asphalt Institute’s fatigue model. The results showed satisfactory performance of all three TDA test sections and significantly longer fatigue lives as opposed to the fatigue life of the control section. This analysis showed compelling evidence regarding the long-term performance of TDA material as road embankments in construction projects.

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The performance of pavement structures is highly dependent on the performance of the subgrade layer, because it is the last layer underlying all the other pavement layers. The development of permanent deformation in subgrade material under traffic loads can cause pavement distresses such as fatigue cracking and rutting. This paper presents an evaluation of permanent deformation behavior of a silty sand subgrade material in the laboratory at various stress ratios and stress levels. It was found that the shakedown behavior of the material fell within plastic shakedown and plastic creep for stress ratios below 1.0 and a stress ratio of 1.5, respectively. A statistical prediction model for permanent deformation based on the test results is suggested.

No abstract