I’ve wondered about the change from concrete to asphalt. When did the asphalt phenomenon take over and why? I have always assumed it was for financial reasons, asphalt being cheaper initially. It turns out that cost is a factor, as well as surface smoothness. Asphalt, when first laid, is smoother than concrete, which factors into better vehicle mileage. Repairs are done easily by simply heating and pouring the asphalt. Concrete repairs, though less frequent, do require more effort. In the end it may not make a difference. This discussion on Snopes.com mentions many of these points. The Colorado Department of Transportation has debated the use of concrete vs. asphalt, mentioning that asphalt is more flexible and permeable, but suffers from wear and tear at a greater rate than concrete, which requires less maintenance[i]. That article was written in 2000, and eight years later, Grand Junction, CO is using concrete in favor of asphalt, in part because the cost of asphalt is rising and the supply is diminishing[ii].
Some arguments for asphalt are that it absorbs heat faster, thus melting ice and snow faster. This makes sense in colder climates. But what about in the south? I feel like I’m melting when walking across a parking lot. Concrete would make summer life much more bearable.
As far aesthetic arguments go, I do not believe that asphalt could win over concrete. Concrete is less noticeable, more earth toned, and thus, it does not take away from the rest of the visual environment. Compare these streets below.
Concrete Street
Asphalt Street
If you consider the connotation of the visual images, concrete always seems historic whereas asphalt seems like modern suburbia. In many cases, if the historic streets are repaved with asphalt, they look completely different. I’m not advocating bricks for that fake historic look, but if it’s concrete, I think it should remain concrete.
What about parking lots? Have you ever looked out of a plane and seen the miles and acres of asphalt pavement covering the earth? It’s horrifying, really. Some places are primarily pavement. How will we ever tear up that surface? We won’t. Long Island is land of pavement, as are many suburban places. In Southern Pines, we, too, have paved surfaces, but in many cases, our parking lots are just dirt covered with pine straw. (For those of you wondering what the heck pine straw is, it’s the dead pine needles of the long leaf pine trees. It’s quite the commodity around here). Of course, this accounts for uneven surfaces more often than not, but it’s much more appealing to the eye and environmentally friendly. It is one of my favorite things about this area.
As many issues, the concrete vs. asphalt choice will vary by town, region, and state. But if it is up to you, I hope you’ll consider all of the factors and not only the immediate cost.
What do you think?
[i] Paula Aven, “CDOT Weights Concrete vs. Asphalt.” Denver Business Journal, May 5, 2000. http://www.bizjournals.com/denver/stories/2000/05/08/story6.html
[ii] Mike Wiggins, “Concrete Now a Viable Alternative to Asphalt Roads,” The Daily Sentinel, November 20, 2008. http://www.gjsentinel.com/news/content/news/stories/2008/11/20/112108_Concrete_roads.html?cxtype=rss&cxsvc=7&cxcat=7
Preservation in Pink 
Economics and durability aside, I agree that the environmental factors of choosing asphalt vs. concrete are very important to take into consideration. You are right about the heat absorption properties of the two materials being very different. The “heat island effect” is the tendency of paved areas and building rooftops to absorb the sun’s energy and result in the microclimate of that area being several degrees warmer than it would be otherwise. Believe it or not this can have a big negative impact on the surrounding ecosystem. The albedo, or solar reflectance, of a material is its ability to reflect the visible, infrared, and ultraviolet wavelengths of sunlight. Concrete has a significantly higher albedo and therefore it is definitely better to use it in warm, sunny climates to mitigate the heat island effect. It may be more acceptable to use asphalt in northern climates (like Alaska) where it may help with snow and ice as you suggested. But I think for most of the continental U.S. it is probably more environmentally sound to use concrete.
However, there are also systems available which are similar to dirt parking lots but slightly more durable (important in some places, for example where erosion may be a factor) and they consist of open-cell concrete systems (to form a grid pattern) with grass in between. This absorbs less heat AND allows stormwater to be re-absorbed into the ground to recharge underwater aquifers. Pervious concrete – made with extra large aggregate and little or no sand, to make a very water-permeable paving susbstance – is another good compromise between durability and sustainability.
And of course the most important factor in decreasing the heat island effect – shade, a.k.a. trees! So lining our streets with mature trees is the way to go!
–Your lovable architecture nerd friend
Here’s a recent article to fuel the fire of this fun debate: http://www.boston.com/news/local/articles/2008/12/07/architect_finds_beauty_in_the_asphalt_jungle/?page=full
I enjoy the blog!
Jen,
I should have known that you would be a wealth of information on this topic! I have never heard of the open-cell concrete system, but it sounds intriguing and like a good idea.
And of course, shade – I love trees, too!
I’m going to make your comment into a post. I think more people should read it, and not everyone gets to see the comments.
Melsiel,
That article is very interesting! Thank you for sharing. It’s a good point of: this is what we have, how can we work with it (not against it) and make it better. Re-imagining it to art surfaces and alternative, cyclical uses is a great place to start. The website that the article links to, http://www.onasphalt.com/index.html, is also very intriguing.
I’ll be interested to see where these projects lead. Thanks for reading and sharing!