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The mean real price of concrete decreases by 20% over 50 years but increases by 95% for asphalt. Photo: Portland Cement Association

The Massachusetts Institute of Technology's Concrete Sustainability Hub has released two reports regarding life-cycle assessment (LCA) of concrete pavements and buildings and one examining life-cycling costing for streets and highways. Among the findings: over 50 years, the mean real price of concrete decreases by 20% and the mean real price of asphalt increases by 95%.

The studies delved into issues — primarily, cost and environmental impact for the asset's entire life — most assessments don't fully explore by adding the use and operations phase, traffic delays, energy consumption, and maintenance to the equation. Conventional assessments figure only the costs and embodied carbon dioxide that occur at initial construction.

In addition, the carbon footprint of concrete pavements can be further reduced. For example, pavements that deflect or bend slightly under traffic loads increase fuel consumption, while stiffer pavements improve fuel economy.

Researchers determined that assessments should include use and rehabilitation, which can account for 33% and 44%, respectively, of carbon dioxide emissions for interstate highways. They used the Federal Highway Administration's Life-Cycle Cost Analysis in Pavement Design Interim Technical Bulletin, a process that accounts for initial construction and future rehabilitation but not changes in material costs over the life of the pavement.

To address this missing link, they developed a paper and a procedure DOTs can adopt to account for inflation.

The three reports can be reviewed at http://web.mit.edu/cshub.