The environmental impacts of airport pavement construction were evaluated in this study through a life-cycle analysis approach. Total primary energy (TPE) consumption and greenhouse gas (GHG) emissions from material production and construction of pavement were determined by using life-cycle assessment (LCA), a quantitative methodology described in the ISO 14040 series. A tool was developed to implement a probabilistic LCA through the Monte Carlo method. This tool allowed for consideration of uncertainty from life-cycle inventory data. A case study on the construction of Runway 10R-28L at Chicago O'Hare International Airport focused on mainline and shoulder pavement designs. Environmental impacts from producing materials for the pavements increased from lower to upper layers, while asphalt layers had relatively higher TPE consumption than the upper portland cement concrete layer—and vice versa for GHGs. Impacts from material production overshadowed those from construction, which contributed less than 2% of TPE consumption and GHGs. Further analysis showed that two production processes—for asphalt binder and portland cement—were the leading contributors (45.3% and 29.2%, respectively) of TPE consumption, while the latter was the leading contributor (73.4%) of GHGs. A probabilistic analysis compared the original 10R-28L runway design and a modified design that did not use recycled materials or warm-mix asphalt technology. The results from 1,000 Monte Carlo simulations showed that the environmental impacts from the two cases were statistically significant, with the original design having lower TPE consumption (482 versus 693 MJ/yd2 for TPE) and GHGs (37.5 versus 53.9 kg of carbon dioxide equivalent per square yard).
Effect of Pyrogenic Silica and Nanosilica on Portland Cement Matrices