System Wide Life Cycle Benefits of Fly Ash

The use of recycled materials in highway construction has the potential to achieve significant benefits affecting the triple-bottom line (environment, prosperity, society). Such benefits include reducing the need for mining virgin materials and transportation (in-situ applications), reducing environmental impacts of processing and transportation, and reducing life cycle costs. Although state departments of transportation (DOTs) 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 easily understood metrics. The main reason for this is the difficulty in tracking the quantities of recycled materials used in state DOT projects. To better define the benefits of using recycled materials, the RMRC undertook a project with two objectives. The first objective was to develop a means of tracking and reporting quantities used in state DOT projects annually. The second objective is to provide a tool to quantitatively analyze and report the environmental and life cycle assessment of using recycled materials in highway construction. A suitable method was recommended after studying how RMRC member states currently track their recycled materials quantities. Subsequently, an LCA analysis of three environmental parameters, energy use, water consumption and CO2 emissions, showed significant environmental benefits when states used recycled industrial byproducts such as fly ash.

2015 World of Fly Ash Conference