Another significant way in which concrete pavement contributes to sustainability is by improving fuel efficiency . It does this by reducing rolling resistance ( that is , the resistance a tire encounters as it travels over a road surface ). CSHub has shown in previous research that stiff , smooth pavements decrease rolling resistance - and concrete pavement is not only stiffer than other paving materials , but it stays smoother longer . Excess fuel consumption ( EFC ) is one of the most significant use phase impacts for pavements , especially on higher volume roadways with a large amount of truck traffic , so concrete pavements stand to make a major contribution to sustainability by reducing the amount of fuel required to overcome rolling resistance .
Mitigating mechanisms
Concrete pavements are more reflective than darker pavements , which is to say they have higher albedo . Albedo is the measure of the fraction of solar energy reflected by a surface . Lighter color surfaces reflect light and have a high albedo , while dark surfaces absorb light and have a low albedo . Choosing pavements with high albedo helps
mitigate climate change and global warming potential by two major mechanisms . One is radiative forcing ( RF ), a measure of the Earth ’ s energy balance . It is the difference between the amount of energy that enters the Earth ’ s atmosphere and the amount of energy that radiates out into space . Increasing albedo radiates more energy out from the Earth and has a cooling effect . A second mechanism is the reduction of urban heat island effect ( UHI ). The lower amount of heat reflected back from a concrete pavement surface , as opposed to asphalt , allows ambient air temperatures to remain lower . A phenomenon receiving increasing attention is concrete ’ s ability to absorb CO 2
. This occurs when hydrated Portland cement is exposed to atmospheric CO 2
, which reacts with the water and the calcium compounds in concrete to produce calcium carbonate . The process is known as carbonation and it occurs as the pavement ages . CSHub researchers have investigated the carbon uptake of all concrete pavements in the United States , running thousands of simulations to calculate the potential carbon uptake in each state based on road conditions , maintenance actions , budgets , and road lengths . They
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