Comparison of Environmental Implications of Asphalt and Steel-Reinforced Concrete Pavements

The public, industry, and governments have become increasingly interested in green design and sustainable development. Construction activities affect the environment significantly, so environmental issues should be considered seriously. Thousands of miles of roads are paved every year with asphalt and steel-reinforced concrete. What are the environmental effects of the two materials? If asphalt has been used overwhelmingly over concrete, is it a better choice for sustainable development? We present results of a life cycle inventory analysis of the two materials based on publicly available data. We find that for the initial construction of equivalent pavement designs, asphalt appears to have higher energy input, lower ore and fertilizer input requirements, and lower toxic emissions, but it has higher associated hazardous waste generation and management than steel-reinforced concrete. When accounting for the uncertainty in the data and when annualizing environmental effects based on assumed average service lives of the two pavement types, the resource input requirements and the environmental outputs are roughly comparable for the two materials. However, asphalt pavements have been recycled in larger quantities than concrete pavements, with consequent resource savings and avoided pollution, which suggests that asphalt may be a better choice from a sustainable development viewpoint. Of course, special functional requirements or economics may dictate the use of one material over the other in particular applications regardless of the overall environmental effects.