Life cycle assessment (LCA) LCA can provide quantities –A protocol to assess the environmental, economic, and social impacts of an industrial system. The life cycle of the industrial system extends from cradle-to-grave: from materials acquisition and production, through manufacturing, system use and maintenance, and finally through the end of the system’s life. 1
oil extraction Aggregate Quarry transport refinery transport placement transport emissions waste hazardous waste other outputs waterfuel other inputs hma plant An example of LCA processes, inputs and outputs to consider for HMA paving.
For a given unit of production (e.g., 1 lane-mile of pavement) a typical LCA gives a range of outputs. Amount of materials used (tonnes) Total energy use (MJ) Water consumption (kg) Emissions –Global warming potential (tonnes of CO 2 equivalent) –Nitrogen oxides – NO x (kg) –Sulfur dioxide – SO 2 (kg) –Particulate matter – PM 10 (kg) –Carbon Monoxide – CO (kg) Toxic things –Human toxicity potential –Mercury – Hg (g) –Lead – Pb (g) –Hazardous waste (kg)
Things people always argue about when looking at LCA data. Functional unit definition –Structural design –Materials makeup Data sources –Asphalt in the mix –Lack of good data (especially for HMA options) –Non-specific data Life cycle –Number and timing of rehabilitation options –Pavement condition
2” lift of SMA 3” lift of ½” Superpave HMA 3” lift of ½” Superpave 2” lift of ½” Superpave 10” of aggregate base (multiple lifts) Subbase 4” lift of ¾” Superpave PCC 13” PCC Subbase 6” lift of CSTC EXISTING PAVEMENT 9” PCC Subbase CSOL Subbase 9” PCC Cracked and seated Petromat Geotex. 2” lift of ½” Superpave 2” lift of SMA 2” lift of ½” Superpave
Contributions from PCC remove and replace
Contributions from HMA remove and replace
Contributions from CSOL
Makeup of Impact Assessment
Impact Assessment Global Warming PotentialEnergy Use
Impact Assessment EutrophicationAcidification
Impact Assessment Human Health Criteria AirPhotochemical Smog
Total Energy Use
Global Warming Potential