Concrete That Purifies the Air 88
fergus07 writes "Although much of the focus of pollution from automobiles centers on carbon emissions, there are other airborne nasties spewing from the tailpipes of fossil fuel-powered vehicles. These include nitrogen oxides (NOx). In the form of nitrogen dioxide it reacts with chemicals produced by sunlight to form nitric acid – a major constituent of acid rain – and also reacts with sunlight, leading to the formation of ozone and smog. Everyone is exposed to small amounts of nitrogen oxides in ambient air, but exposure to higher amounts, in areas of heavy traffic for example, can damage respiratory airways. Testing has shown that surfacing roads with air purifying concrete could make a big contribution to local air purity by reducing the concentration of nitrogen oxides by 25 to 45 percent."
Old News? (Score:1, Informative)
Saw this back in 2006 ... business week article [businessweek.com]
Still seems like a good idea though, as long as you're not trading one set of problems for another.
Re:But at what cost. (Score:2, Informative)
Re:Concrete roads are shit (Score:5, Informative)
Also you can't use salt to de-ice in the winter. Destroys the concrete surface quickly, which is why there are some concrete highways in the Southern US, but none in New England...
Re:Concrete roads are shit (Score:2, Informative)
This is an update (Score:2, Informative)
This is an update on the results of the testing.
Re:Old News? (Score:3, Informative)
You're right. In fact, I saw this on slashdot in 2006.
Re:Old News? (Score:3, Informative)
You're thinking of phosphates. NOx causes smog.
Re:Concrete roads are shit (Score:1, Informative)
What do you think is under that tarmac?
Typically you concrete first. 6-8 inches depending on traffic load.
As cracks appear you then layer asphalt on top of that recreating a smooth surface again. Asphalt by itself is not strong enough for highway usage. Not unless you *LIKE* pot holes and ruts in the road. And ruts will form. As Asphalt is almost a liquid being a tar petroleum derivative.
For example in Nebraska between Lincoln and Grand Island is asphalt road. Major ruts from the 18 wheelers that drive continuously down I80. It gets a 'tad' warm in Nebraska in the summer (100-110 max). Not enough to melt the roads but enough to soften them up a little. Then add in 24/7 75 mph traffic. Then the problem they have is gets cold in nebraska for several months of the year (32 to -10).
Between Lincoln and Omaha they have been quietly replacing that type of road with concrete and a asphalt surface.
The problem with roads is if you make them durable that they do not change they end up being to brittle. If you make them able to handle 'fixing themselves' then you end up with a 'gooie' road and ruts form. So they mix materials to get the 'best' of both.
In lower California you see lots of concrete as the temps are fairly stable. As you start with that. Wait for cracks to form then asphalt over it. The cracks will come back eventually. But then you scrape off the asphalt melt it up and pour it back on. You need the concrete to absorb the energy from the cars driving over it. Asphalt is not up to that job. At least not long term (10+ years). It may work for your driveway. But put any sort of traffic on it and it would crack and rut very quickly without something supporting it.
Re:just moving the problem (Score:1, Informative)
Re:Old News? (Score:3, Informative)
I dug up the link to: http://science.slashdot.org/story/06/11/10/041214/A-Concrete-Solution-To-Pollution [slashdot.org]
Re:just moving the problem (Score:3, Informative)
Titanium is pretty common. The hard part with it is getting it into alloy form because it has to be smelted without oxygen present or else you get a bunch of titanium dioxide, a lit fart or two, and not much else.