Sometimes my urge to satisfy my intellectual curiosity can be rather exhausting. There have been nights where I have lost hours of sleep just because I was thinking too much. One of the more recent nights I was plagued by the question “why are some roads asphalt and others concrete?” Naturally that sparked other questions, most notably “why is asphalt more common?”I can safely say everyone who has driven has been on both, and the average person probably hasn’t cared what the difference between them is, but I because I became so engulfed by the need to figure it out, I did a little investigating. And here is what I’ve come up with.
As with anything, it’s all about the money. Concrete is more expensive, ranging from 30%-45% more per unit. So naturally, given all other considerations being equal, asphalt is the better choice. This seems to explain why the vast majority of roads are asphalt–because it’s cheaper.
However all the things are not equal when comparing the two materials. Each provides there own advantageous and disadvantageous, which further validates the use of one material over the other. Asphalt is a petroleum based product, making is a very fluid like material. Therefore between the two materials, this is easy to lay, since one only needs to “pour the material” and let set on it’s own. This quality also makes it much easier to repair cracks since you can just pour in more asphalt. A downsize of asphalt is that it israther porous (comparatively) making it more susceptible to water damage, causing asphalt to degrade more quickly. The average life for a moderately traversed road is 30 years. Lastly, the most obvious attribute of Asphalt is that it’s black, and everyone knows how hot black roads can get in the direct sunlight. Yet this problem isn’t just a inconvenience to the barefooted, if the road gets hot enough, the material becomes malleable and can cause structural damage to the road.
Concrete, from a material science perspective, is much more rigid and therefore much stronger. This quality makes concerete the ideal choice for any significant structural units such as bridges, freeways and parking garages. When you combine it with steel reebars to provide additional support, concrete becomes a very strong and structural sound building material. In contrast to asphalt, concrete is water proof, a significant advantage over asphalt. But it too has it’s weakness–salt, used to de-ice roads in colder regions of the country, can be very damaging. Given it doesn’t experience ice damage, concrete roads can last 50 years. Yet because of the rigidity of the material, one can not simply “pour” in new concrete to repair any cracks. To effectively repair the road, the must be laid out from scratch–our you can also fill in the cracks with some asphalt and get the best of both worlds (kinda…).
In conclusion, it really depends on what you are looking for. Both have their advantages and disadvantages, so it’s up to what you need it for. That’s probably more than you’ve eve cared to know about asphalt and concrete, but since both are such ubiquitous materials, it’s good to know a little about it. Hey, you never know when you’ll be relaying your driveway, and at that moment, you’ll be appreciative that you know everything there is to know about Asphalt and Concrete!