Concrete vs. Asphalt highways?

Joined
19 February 2003
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Maryland
I just came back from vacation to Florida. I drove from Maryland. I never really understood why some stretches of road are concrete and some are asphalt.

I know concrete is stronger and probably a little more expensive to put down. There are stretches of I-95 that are concrete and horribly bumpy. Asphalt always seems much nicer to drive on. Although there is a stretch of road on South Carolina that has very nice concrete, but I don't know how old it is.

Anyone know the answer? I would think asphalt is more economical to put down but yet concrete still persists.
 
The only thing I could think of is asphalt is alot more slippery in the rain and we get LOTS of that?

The roads in Florda (S. Florida especailly) SUCK. I-95 is under construction year round and the turnpike is usually pretty darn backed up.

Only highway I like down here is I-75 and the Sawgrass...75 is a 5 lane (at some points) stretch of road that is a 70mph with very little police surveillance.
 
I thought concrete was cheaper... nonetheless, it does last a lot longer, but I find it much noiser to drive on...

If only americans roads were built like the autobahn!
 
From the website of a local construction company:

Concrete and Asphalt Pavement Differences

Historically, pavements have been divided into two broad categories, rigid and flexible. These classical definitions, in some cases, are an over-simplification. However, the terms rigid and flexible provide a good description of how the pavements react to loads and the environment.

The flexible pavement is an asphalt pavement. It generally consists of a relatively thin wearing surface of asphalt built over a base course and subbase course. Base and subbase courses are usually gravel or stone. These layers rest upon a compacted subgrade (compacted soil). In contrast, rigid pavements are made up of portland cement concrete and may or may not have a base course between the pavement and subgrade.

PCvsAC.gif


The essential difference between the two types of pavements, flexible and rigid, is the manner in which they distribute the load over the subgrade. Rigid pavement, because of concrete’s rigidity and stiffness, tends to distribute the load over a relatively wide area of subgrade. The concrete slab itself supplies a major portion of a rigid pavement's structural capacity. Flexible pavement, inherently built with weaker and less stiff material, does not spread loads as well as concrete. Therefore flexible pavements usually require more layers and greater thickness for optimally transmitting load to the subgrade.

The major factor considered in the design of rigid pavements is the structural strength of the concrete. For this reason, minor variations in subgrade strength have little influence upon the structural capacity of the pavement. The major factor considered in the design of flexible pavements is the combined strength of the layers.

One further practical distinction between concrete pavement and asphalt pavement is that concrete pavement provides opportunities to reinforce, texture, color and otherwise enhance a pavement, that is not possible with asphalt. These opportunities allow concrete to be made exceedingly strong, long lasting, safe, quiet, and architecturally beautiful. Concrete pavements on average outlast asphalt pavements by 10-15 years before needing rehabilitation.
 
ken, you are the best online encyclopedia. You should start a "www.askken.com" search engine. :D You even have a diagram to support your explaination.

i just learned something today. thanks ken!!
 
NeoNSX said:
ken, you are the best online encyclopedia. You should start a "www.askken.com" search engine. :D...

Or there should be a forum here! Why not take advantage of a valuable resource.
 
NeoNSX said:
ken, you are the best online encyclopedia. You should start a "www.askken.com" search engine.
There's no need for a new search engine; just type in "concrete asphalt pavement" into www.yahoo.com and you'll find that site as the first link listed. How do you think I found it? :D
 
Economics

It really boils down to economics. Pavement surfaces has a finite life and must be replaced at certain time intervals. Concrete costs more than asphalt, so a state’s highway department engineers will work out the economics.

There is another factor to consider, and that is the climate. Where the soil is predominately clay, the soil expands and contracts with moisture content variations. Concrete is not as flexible as asphalt, so when it cracks the cost is higher for repair.
 
Blacktop is quieter, but needs more maint. attention . Blacktop also is hard to see at night especially if raining. If the road lines are old and faded, you have a difficult time making out the road.

In snowbelts, blacktop takes a beating from temp. change and plows vs concrete.

Easier to do burnouts on blacktop! :D

its a tie.
 
NetViper said:
I thought concrete was cheaper... nonetheless, it does last a lot longer, but I find it much noiser to drive on...
Around here, the state laid asphalt on many concrete freeways due to noise complaints. I think asphalt is more maintenance intensive (needs to be recoated every few years, especially in this heat), but whatcha gonna do? After all, it's not like people who bought houses next to the freeways would have *expected* traffic noise, right? :rolleyes:
 
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