Life-Cycle Benefits of Recycled Material in Highway Construction

Abstract

The use of recycled materials in highway construction can achieve significant benefits affecting the triple bottom line (environment, prosperity, and society). Although state departments of transportation have been at the forefront of introducing recycled materials, they have been unable to clearly convey the benefits in a quantitative and transparent manner using easily understood metrics. Information on sustainability assessment characteristics—that is, energy and water consumption—is lacking. To determine the benefits of using recycled materials for six member state departments of transportation in a pooled fund, the Recycled Materials Resource Center at the University of Wisconsin–Madison was tasked with a project that would quantify the environmental and economic life-cycle benefits associated with the incorporation of recycled materials and industrial by-products in highway construction. An analysis of the environmental benefits (i.e., carbon dioxide emissions, energy consumption, and water consumption) associated with the substitution of recycled materials for conventional virgin materials in highway construction was conducted using the pavement life-cycle assessment tool for environmental and economic effects, a tool developed with the sponsorship of the Recycled Materials Resource Center. An economic impact analysis was conducted by comparing the unit prices of virgin and recycled materials. The analysis showed significant environmental and economic savings in all member states. Total environmental savings from use of recycled materials were approximately equal to the energy consumption of 110,000 U.S. households per year, 9,300 bathtubs of water, and the carbon dioxide emissions produced by 58,000 cars per year. Total systemwide economic savings from use of recycled materials was estimated to be $62.5 million.