A framework based on engineering performance and sustainability to assess the use of new and recycled materials in pavements
Growing need for increased use of recycled and new materials in road construction has emerged due to the continuous depletion of natural resources and increased impact of the current state of practice on the environment. Sustainable construction practices have been favoured by Federal and State Departments of Transportation as well as the industry. However, the impacts of using new and recycled materials in pavements, particularly on long term pavement durability and performance, are often unknown. A comprehensive procedure for evaluating these "proposed materials" in terms of engineering performance and sustainability is very significant for making appropriate decisions on whether to use them for road construction. The research is performed based on whether the material is proposed to be used in asphalt, concrete, or in unbound layers. An analysis framework and, a software (called NewPave) was developed to help the Michigan Department of Transportation (MDOT) identify the impacts of new and recycled materials on pavement performance and the environment. The analysis framework included two basic components; (i) engineering performance, and (ii) sustainability. Engineering performance evaluation included several options for each material type to be used in different pavement layers. The sustainability analysis included three basic components; environmental, economic and social analyses. Finally, the scores obtained from the engineering evaluation are combined with those based on sustainability to obtain an overall score. The overall score can be used to accept/reject the trial use of the new and recycled materials in MDOT administered roads. While the framework presented herein was developed for MDOT, it can easily be adapted by other DOTs.