Evaluation of recycled material performance in highway applications and optimization of their use

In the United States, solid waste is being generated at an increasing rate, and its disposal is becoming a huge problem for the communities involved. Solid waste comprises of a broad range of materials. Currently, the primary solid waste disposal methods are incineration and landfilling. Although incineration helps reduce the volume of waste, the resulting ash still ends up in landfills. Furthermore, concerns have been raised about the negative effects of incineration on air quality.

Highway construction typically involves the use of large quantities of natural resources such as construction aggregates. Furthermore, in many parts of the United States, good quality highway materials are in short supply. Cost of conventional materials continue to increase due to reasons such as depletion of natural resources, rising cost of mining, and high transportation costs. This, combined with the rising costs of waste disposal, has made recycling an attractive option to reduce the burden on landfills and also to save valuable natural resources.

For several decades, transportation agencies have been conducting research on the use of recycled waste material in construction projects. However, a large number of these studies involved laboratory characterizations of recycled waste materials to develop technical specifications for their use. However, this is not a comprehensive approach to the problem, and it has not led to widespread use of recycled materials except for a very few cases. This dissertation evaluates recycled material use from engineering, economic, environmental and performance points of view to conduct an overall assessment of the feasibility of using such material in transportation projects. It includes long-term monitoring of projects constructed using several recycled materials. A framework to optimize the use of recycled materials is also developed using glass cullet as an example. This framework is based on laboratory evaluation, structural and economic analysis.