Posting in Energy
By adding recycled tires to asphalt, we can make roads quieter and more durable.
Whether we recognize its occurrence or not, noise pollution may be wreaking havoc on our lives. According to the World Health Organization (PDF), unwanted noise can lead to major health problems such as heart disease, cognitive impairment, and perhaps most obviously, sleep disturbances.
And while not much can be done to quiet loud neighbors or low-flying planes, engineers now have a way to lessen the racket on the roads. According to a new issue of The Economist, adding rubber to new roads can significantly lessen the effects of noise pollution all while making the infrastructure itself more durable.
To make quieter streets, engineers can add rubber “crumbs,” or rubber from recycled tires, to the bitumen and stone used to make asphalt. The resulting softer pavement not only cuts traffic noise by 25 percent, it also lasts longer than the normal variety.
So how exactly does recycled rubber lead to quieter roads? The Economist reports:
Pores between the stones in standard asphalt must be small, because if the gaps are too big the bitumen binding cannot do its job properly. Adding rubber thickens the bitumen. That allows bigger pores, which help to trap and disperse sound waves. The rubberised bitumen itself is flexible and slightly springy, which enables it to absorb more unwanted sonic energy.
The new roads are also cheaper to make than the traditional variety. Not only is the rubber made from discarded tires—a plentiful product in the Western world—but it can also partially replace bitumen. Bitumen, the main binding agent in pavement, is derived from oil, meaning its price will likely continue to rise as the cost of crude oil skyrockets.
Not surprisingly, rubberized roads are already catching on with popularity in the United States, China, Brazil, Spain and Germany.
[via The Economist]
Image: Mykl Roventine/Flickr
Jul 1, 2012
It is really nice to read in this blog that the rubberized roads not only help lessen notice but they also are cheap to build, I like it a lot. http://www.tyre-shopper.co.uk/branches/accrington
the auto ignition, point at which the material will spontaneously combust is said to be 900 degrees F. The flash point, the lowest point at which material will burn under certain conditions such as a car that catches fire, etc. is 350-425 degrees. It's important to keep in mind the flash point can vary depending on the specifics of too many possibilities of factors and conditions to mention that could effectively come into play that would alter that number. For example if that same car fire took place on a rubberized highway with more fuel absorbed into the surface that number would likely be a bit lower. However, from what I can tell, there seems to be little variance from that of typical asphalt material. It's auto ignition point is 900 degrees F. and not a factor that would prohibit its use in places of extreme heat At the rate global warming is going it shouldnt be a concern for at least 3-5 years.(I'm joking of course)!
I believe Smartplanet (or some other source) had a report on the efffect of road construction on vehicle mpg that related improved gas mileage with LESS flexibility of the surface. Perhaps a compromise can be found in using rubberized asphalt in residential areas and the noisier paving in higher traffic zones. Another interesting article is at: http://news.nationalgeographic.com/news/energy/2011/10/111017-asphalt-concrete-road-building-energy/#
Just maybe we might consider to have some observers make a trip to The Netherlands and find out how to builde and maintain roads. My wife and I were there a couple of months ago and found all the roads are excellent and well maintained.
Washington State has already been using this addition to parts of Highway 101. There is one thing to consider, though. One hot summer the highway caught on fire. This is no joke. Look it up.
Up until 3 years ago, we lived on a quiet, dead end gravel road. The county wanted to take our land and build a through road but couldn't get past the environmental impact of excessive noise, until some engineer came up with the idea of using rubberized asphalt. Voila! Magically that made it pass the noise requirement. They put the road through. I don't think that rubber made a damn bit of difference. We now live on a busy, noisy street. Don't believe everything you read.
It should be obvious by now, that in order to get everyone interested in a 'new' process, even if it's a type of road, we just bite the bullet and hire a pop star or hip-hop artist to talk about it
We've been adding such rubber shreds/pellets to roads for 50 years. I recall reading about and later talking with the manager of the asphalt plant about a test stretch west of Cincinnati, and they mentioned it did have a nice surface. Don't recall whether it was said to have lasted especially longer. It will still deteriorate the same as any other MacAdam surface. The oils and gasoline and sunlight attack both the asphalt and rubber, and the loads and freezing and thawing and water being forced into every crack eventually break it up. In Minihopeless they use concrete, replacing whole pads between expansion joints over-night when the freezing and thawing pops one out of position, but when they do pop it can be devastating.
this is a multi-purpose discovery. adding rubber to the mix has outstanding benefits to roads and to our cars. less front end damage from potholes and bumps better handling, etc. far less noise from traffic, etc. we can fix bad roads as they degrade until all roads are fixed up with this mix. I think it's a no brainer. an efficient and environmentally helpful use of discarded tires. there is no need for manufacturing the stuff we already have mountains of it in every city. asphalt is just not strong enough. potholes are fixed and they are back again a month later. discarded tires are being used for more things nowdays. it's a great recycled product.
I remember seeing someone doing this almost 25 years ago on a late night news show (60 Minutes or 20/20 (is that show even on anymore?!)). The "trial" road was one in the high desert somewhere near Arizona, if I remember correctly-- a place which experienced a wide range of weather and traffic conditions. In addition to a quieter surface, I seem to recall the rubberized asphalt had a greater temperature threshold and was less susceptible to cracking, giving it a longer life. At the time though, it was considered too expensive to consider replacing roads with it. Of course, replacing a road is expensive enough as it is, so naturally councilmen are going to balk when given the decision. I don't remember any mention of fuel efficiency, but I can see where that would be a concern. The way I look at it, vehicles are getting more fuel efficient all the time. Even if this greater efficiency doesn't even out with the less efficient road, I would rather pay more in fuel over time than in insurance premiums, hospital bills, or funeral expenses at once.
I don't think anyone is suggested ripping up existing roads, but rather working the rubber into the mix when the roads need to be resurfaced. My concern is MPG, wouldn't that drop on softer roads?
Loop 1 in Austin uses a special asphalt that dampens road noise and is less slick in rainy conditions. It's great. It's not made from old tires, but we have playground surfaces made from old tires, and they're great, too.
I don't recall how long ago it was resurfaced, but there's a section of I-10 that I frequently travel on that has had the recycled tire surface for several years now. I noticed the quiet immediately, not knowing how they did it until later. It seems like, however, there was an article on Smart Planet about fuel efficiency suggesting that concrete was considerably better. Unfortunately, fuel efficiency and safety are sometimes at odds, because less friction means better mileage, and less grip. I don't think the mileage difference is that great, though, and the quietness is probably well worth it. Whatever surface is used is a compromise, and the quiet and safety are probably well worth any tradeoff in fuel efficiency. Increased fuel efficiency can be achieved from the vehicles themselves.
A few obvious snags here - You would need to dig up and re-lay thousands of miles of roads. Most federal/goverment/state/council/ highwat agencies depending on your country are critically short of money these days, otherwise the worn out roads the rubber ashphalt will make last longer would already have been fixed - makes this a no chancer - Assuming the rubber would not perish in the being laid process, as ashphalt being put down is a high temerature process - Assuming the rubber would not just peel out of the road again in hight temperature where traditional askphalt/bitumin can seep out Suggested alternatives which avoid needing to rip up roads at vast cost. In some countries, their is a minimum tread depth for safety in wet conditions. The larger the tread is over the safe depth, the better road holding you get. In some countries, their is a MOT test - where vehicles are checks for fitness for the road. Perhaps make this more rigorous. Make traction control/ABS a legal standard for all new vehicles - this always helps with safe driving Make tyres wear out quicker - The 'rubbbering in' comonly seen on race tracks - see Formula One from Free Practice 1 to final Qualifying 3, where there is so much rubber now on the road, esp. from soft/super soft option tyres, grip is massively improved leading to better handling.
They will argue for hours that the taxpayers should pay on $75 for road design X instead of $100 for design Y. They will say that design X is a good buy for the taxpayers. What they neglect to talk about is the long term math. Design X lasts 5 years until it needs to be resurfaced while design Y last 10 years. So really the discussion needs to be, do you want to pay $150 for 10 years of design X? Or do you want to pay $100 for 10 years of design Y? Often the promoters of design X paid more campaign donations than the promoters of the newer design Y. Guess who wins?
Generally speaking, they don't rebuild roads until they need to, so the new surface would be applied at the end of the current road's useful life. Regarding the question about the rubber surviving the process, they've been testing this for a number of years now with (as far as I can tell) good success. It certainly works. The only possible unknown is the durability. I don't know what the findings have been in that regard, and the article doesn't mention it.