Will We Get Hot Enough to Melt Asphalt? Inquiring Minds Want to Know!
As a child, and even some of us adults, we shoved sharp objects into asphalt, just to see if it will go in during very hot weather.
With a high of 108 coming Wednesday, we wondered if it's a myth that asphalt will melt. Actually the answer is yes, and no. But let's explain.
According to various scientific sources, when a road is being paved, the asphalt mixture is usually heated to at least 250 degrees, sometimes 275. This allows it to be poured easily. Some of it also depends upon the tar vs. rock and binder mixture. Pure tar by itself becomes rather gooey and can be poured at over 200 degrees.
So, we'd have a while to get there before our roads melt. But, since we know that dark surfaces absorb heat and become much hotter than the real air temp, the roads could become soft enough to shove in a screw driver.
Thermal guns are used by paving companies and other builders to determine temperatures on roads. Commonly known as pyrometers, these devices are pointed at the surface of a road, and give you an infrared reading.
According to various sources, including Yahoo.com, on a 108 degree day the asphalt surface can become as hot as 160 degrees. By the way human skin can begin to seriously burn at 140, enough heat to cause injury. With pavement anywhere from 140-160 it will begin to get soft.
So next Wedesday, try sticking that screwdriver into the pavement, and see if it goes in. It works especially well on newer roads, because they are much darker and absorb more heat. Just don't go barefoot, or let the dog run across a hot road. It can actually burn the pads on their feet.
By the way, we did find reports from a 2015 heat wave in India, where air temperatures of 120-122 degrees did cause roads to become so soft they were dangerous to drive on. That was also attributed to lower quality pavement, combined with asphalt temps that hit an estimated 180 degrees or hotter.