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Los Angeles Tests Reflective 'Cool Pavement' On Streets (dailynews.com)
mikeebbbd writes: As reported in the Los Angeles Daily News, during the current heatwave various officials swooped down on streets coated with an experimental light-gray sealer that makes the old asphalt into a "cool street" -- and it works, with average temperature differences between coated streets and adjacent old asphalt around 10F. At a large parking lot, the temperature reduction was over 20F. If the material holds up and continues to meet other criteria, LA plans to use it on more pavement rehab projects, which could eventually make a difference in the heat island effect. The "CoolSeal" coating is apparently proprietary to a company named GuardTop LLC, costs $25-40K/mile, and lasts 5-7 years. At that price, it's might not be used a lot, at least at first; typical slurry seals run $15-30K/mile.
Lighter color coatings reflect more heat. Complete with expert testimonials!
“I feel a slight difference on the street and inside my apartment,” said Priscilla Corleto, 24, walking Gatsby, her small white Shih Tzu. “Without the AC, it seems cooler.
Might be cheaper to plant trees and landscaping in an urban environment. Several tech companies are using rooftop gardens to put the heat to better use.
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we're currently ignoring the whole water shortage thing here in Arizona. It'll bite us in the next 20 years. The wealthier parts where I'm at are crazy with how much green there is. It's like they terraformed the landscape. You can do that when water's cheap due to subsidies but that's not going to last forever.
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Concrete is much more expensive than asphalt. It's also harder to install and maintain. While slabs of concrete may last longer, it doesn't do much good if it becomes irregular (kathunk kathunk kathunk .. for 100 miles). It can't be resurfaced as easily (no grinding down the top and pouring 2 inches of additional concrete on top) as asphalt either. It has use cases on grades that are steep, or where heavy travel craters the asphalt in hot areas (stop lights, downhill braking, etc).
That is great and all until you realize that the places that need this were built on desert.
Using concrete without a coating of asphalt on top has a similar effect... how about just paving with concrete. It lasts longer, requires less maintenance, and is cooler. If made thick enough it can also be ground down to "resurface" it several times without any need to add more concrete unlike asphalt roads.
Using asphalt is only done because asphalt is a byproduct of the petroleum refining process and the oil companies have done everything they can to ensure they can sell their waste and force us to use it so they can avoid having to pay disposal fees for the stuff.. And while asphalt *can* be recycled, it also pollutes more than most folks care to believe. The pollution caused by the use of asphalt is right there with the pollution caused by tires... both of them break down into smaller and smaller pieces and make their way into the environment... and the stuff is everywhere, not unlike the lead that used to spew from tailpipes just a few decades ago. Manufacturers of asphalt and tires are even responsible for a far greater evil than simply polluting because we need roads and tires and don't have another option at the moment... the pollution they cause is far greater than it needs to be thanks to efforts to make the products as cheap as possible which leads to premature and excessive wear. Good quality asphalt and tires wear out far slower and therefore pollute less, but greed makes that at best a tertiary concern for profit motivated corporations.
The simple solution is to use concrete tires on the cars as well.
They started doing this in Tokyo several years ago. They painted a lot of major roads green. I was worried about them being slippery in the rain, at first, but they turned out to be no worse than bare asphalt, and I believe they helped stem the heat island effect.
j'ai découvert une démonstration vraiment admirable (de ce théorème général) que cette si