Quantification of System-Wide Life Cycle Benefits of Recycled Materials in Highways

Project Details









Ahmet H. Aydilek




Cost effectiveness, Environmental impacts, Life cycle analysis, Maryland, Recycled materials, Road construction, Waste products

Project description

The Federal Highway Administration (FHWA) and various governmental agencies have developed fact sheets on various recycled materials and industrial byproducts for their use in highway construction applications. These fact sheets typically have addressed the engineering properties and environmental suitability issues relevant to various applications and in some cases incorporated design guidelines and construction specifications. What is lacking is direct information on sustainability assessment characteristics, i.e., greenhouse emissions, energy and water consumption and life cycle cost benefits. Agencies may track system-wide use of quantities for major recycled materials such as fly ash, recycled asphalt pavement, recycled concrete aggregate, foundry sand, coal combustion byproducts, steel slag, etc., but they cannot readily calculate the benefits accrued by substitution of these materials for conventional materials. Although state transportation departments have been in the forefront of introducing recycled materials, they have not been able to clearly convey the benefits in a quantitative and transparent manner using readily understood metrics. The first objective of this study is to develop/update fact sheets on various recycled materials and industrial byproducts that are used in highway construction. New information generated in recent years relative to their engineering properties and environmental impact questions will be added as well as relevant life cycle assessment data. The second objective of this study is to develop a tool by which the state system-wide material use quantities can be used to calculate the life cycle benefits associated with the incorporation of recycled materials and industrial byproducts to highway pavement construction. (1) Develop/update fact sheets on various recycled materials and industrial byproducts that are used in highway construction; (2) Identification of the most appropriate cost database for life cycle assessment parameters for each material; (3) Integration of cost effectiveness and environmental impact into current materials testing and evaluation; and (4) Determining the benefits accrued by use of recycled materials and industrial by products in construction through a highway rating system. Various states including Maryland Department of Transportation (DOT) plans to adopt a green materials management approach. This research project directly helps the DOTs build their capacity to sustain such efforts. The life-cycle analysis method evaluted through actual field projects in this research will provide an easy-to-use tool for DOT engineers to evaluate the impact of green materials and technologies in terms of environment, cost, and long-term performance. The successful implementation of this project could also lead toward the development of green materials registry and management at the DOTs. Recommendations provided in the final report can also lead to pilot implementation for full-scale evaluation of the developed life-cycle analysis tools.