Concrete vs Asphalt
If you want to look at concrete and asphalt along side each other, look at these pictures under a street-light after dark and in daylight. In daylight the conversion of sun rays into heat and released volatiles is even more pronounced. You can also see that concrete requires less artificial light at night because it reflects light better. The less energy used in lighting the better, because fossil fuels are usually burned to generate electricity, thus adding greenhouse gases to our environment.
Night time and daytime pictures showing reflectivity of concrete vs. asphalt. Asphalt requires more lighting at night to provide the same visibility as concrete. |
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Asphalt absorbs sunlight and converts it into heat. In the hot summer sun it can reach over 140°. This is a big contributor to the Heat Island problem. Even when the sun goes down it continues to give off heat, adding to our air conditioning load at night. Once the temperature rises above 90° engine emissions are converted into smog. The National Center for Atmospheric Research (NCAR) reports that Volatile organic emissions increase by 15% to 25% for every 1.8° F. temperature increase.
What difference do heat islands make? Asphalt softens and forms ruts or ripples as brakes applied to vehicle tires pushes around softened asphalt. After many thousand deflections ruts, humps or potholes form.
This is why asphalt need so much maintenance. The softer asphalt also offers more resistance to trucks requiring up to 10% more fuel. That also adds more heat and green house gasses, adding to global warming.