If roads were reinforced with rebar...

[imported_goku]

If commonly used roads were reinforced with rebar, would we not have to resurface the roads as much? Would it save us money in the long run to just reinforce commonly traversed roads with rebar due to the lessening of resurfacing?

 

[bctbct]

rebar in flat work makes the concrete stay in place after it cracks, not really stronger like in a column or a beam.

 

[fitzov]

It would be hugely expensive--more than it costs to repair the roads when they need it.

 

[Trevelyan]

Originally posted by: fitzov
It would be hugely expensive--more than it costs to repair the roads when they need it.

Exactly. Same reason we use asphalt instead of concrete for the majority of roads.

 

[GagHalfrunt]

Nope. Rebar gives tensile strength, nothing else. Pot holes are caused by tiny cracks in the concrete that get water in them. The water destroys the concrete from inside the crack, especially in cold climates where there's a freeze/thaw cycle. Roads with rebar would still react the same way, they'd crack right around the rebar.

 

[cavingjan]

It would not be worth the cost and the repair expenses associated with ASR (alkali silica reactions) and the common use of road salts in the winter. Its bad enough with road salt on the road surface but to have it work its way underneath the concrete and to the rebar in the soil is just begging for problems.

 

[LeadMagnet]

495 in Mass was concrete with rebar since the day it was built in the 1960's and it was never resurfaced - however when the decided to replace it in 2000 it was a massive undertaking because the old road needed to be smashed and removed.

 

[MikeMike]

wait, what roads are even concrete?

we cant use concrete because of the temperature variances, especially in any area that has freezing temperatures.

asphault is used because it can actually take heaves, and what not, while not breaking and cracking as easily.

 

[cavingjan]

Originally posted by: Trevelyan

Originally posted by: fitzov
It would be hugely expensive--more than it costs to repair the roads when they need it.

Exactly. Same reason we use asphalt instead of concrete for the majority of roads.

Asphalt is currently used because it is cheaper to use and repair (grind off top couple inches and recycle it back into the road with fresh binder) every 8 years than to build a concrete road that has a service life of 20 years.

Interestingly enough, there was no significant price change over the past two years due to the oil even though that is a primary ingredient of the binder.

 

[amdskip]

Concrete is used in plenty of places where it is cold. I've seen roads with a concrete base and an asphalt overlay that becomes sort of the wear layer so it can be ground off and reapplied. Plenty of interstates have just concrete and they do definately put reinforcement in them but it's not steel rebar, it's more of these weird shaped little things.

 

[Trevelyan]

A lot of interstates are concrete. I would assume that's because they will go a lot longer without repairs, and shutting down an interstate to lay down new road would not go over well.

 

[funboy6942]

Alot of asphalt roads are being replaced with concrete.

 

[MikeyIs4Dcats]

most roads are concrete. they may be overlaid with asphalt in order tyo extend the life, but eventually they will be torn out and replaced with new concrete. money is always lacking, so it usually takes a ling time.

 

[Yzzim]

Actually, most roads are Asphalt Concrete

http://en.wikipedia.org/wiki/Asphalt_concrete

 

[KLin]

Originally posted by: MIKEMIKE
wait, what roads are even concrete?

we cant use concrete because of the temperature variances, especially in any area that has freezing temperatures.

asphault is used because it can actually take heaves, and what not, while not breaking and cracking as easily.

Caltrans is currently pouring new lanes for a section of hwy 99 through central california and they're using concrete. They're using rebar for reinforcement too.

 

[Wreckem]

Originally posted by: Yzzim
Actually, most roads are Asphalt Concrete

http://en.wikipedia.org/wiki/Asphalt_concrete

In Texas most new roadwork is being done with concrete. Almost all the major highways and interstates in Texas are concrete, though some have asphalt on top of the concrete. Even a lot of municiple road work is being done in concrete.

 

[Jeff7]

Originally posted by: GagHalfrunt
Nope. Rebar gives tensile strength, nothing else. Pot holes are caused by tiny cracks in the concrete that get water in them. The water destroys the concrete from inside the crack, especially in cold climates where there's a freeze/thaw cycle. Roads with rebar would still react the same way, they'd crack right around the rebar.

I've read about one method with rebar, in which the rebar is put under tension while the concrete is poured, then once the concrete solidifies, the rebar is released, putting the concrete in compression, which is what concrete deals with best. I guess that this process would add to the cost though.

 

[bctbct]

Major roads and highways are first constructed out of concrete. When they begin to crack they are overlaid with asphalt because it is cheaper.

Then they are frequently overlayed with asphalt again. Then they may be ground off and then overlayed again.

When the concrete underneath has deteriorated to a certain point that it no longer provides a stable base, it is torn out and replaced with new concrete and the process starts over.

Asphalt is not a very good road by itself. In fact a motorcycle kickstand will go thru a 3" lift of asphalt unless it has a good gravel or concrete base. Asphalt also mushrooms out when laid more than 2"-3" thick.

Asphalt is much cheaper and that is why it is used tyo extend the life of roadways until replacement is inevitable.

 

[DrPizza]

Yes, many roads are concrete.
Yes, many concrete roads DO use rebar/other reinforcement. That still doesn't stop the potholes (see I86 in western NY between Salamanca and Cuba)


However, IIRC, certain materials (silicon carbide fibers?) can be added to asphalt to make it extremely durable. But, apparently, it's rarely used in the US.

 

[uberman]

Our roads are built poorly. I don't know why they do this, but here's the scoop. American roads are built to last for a short term. Roads in Europe are designed to last twice as long. The ratio is 2 to 1. Roads here rebuilt every 10 years, in Europe, every 20 years.
Source: I believe the documentary was on the Learning Channel, but I've also heard it elsewhere.

 

[sdifox]

How else are the paving companies going to keep making money? Long gone are the days of do it once and forget about it. It's all about planned obsolescence.

 

[j00fek]

i dont think so

 

[ElFenix]

most of the highways around houston are rebar concrete. sometimes asphalt will be poured on top to extend the life. most of the side streets are concrete as well (with heavily trafficked streets getting a layer of asphalt).

asphalt sucks ass. it doesn't stay where you put it. it buckles under weight. it's hard to repair properly.

 

[OutHouse]

they do. all the new sections of the interstates that i have seen put in are made from concrete and before the concrete is poured i see guys out there laying rebar.

 

[Theguynextdoor]

Originally posted by: uberman
Our roads are built poorly. I don't know why they do this, but here's the scoop. American roads are built to last for a short term. Roads in Europe are designed to last twice as long. The ratio is 2 to 1. Roads here rebuilt every 10 years, in Europe, every 20 years.
Source: I believe the documentary was on the Learning Channel, but I've also heard it elsewhere.

That's because in Europe their workforces is all very centralized as opposed to the US where it's very spread out. We have more mi's of road then most of Europe combined. But only one workforce.