Expansion of concrete

[chicopee]

I did not think that concrete would expand so much as to upheaving several inches during a 93 dF ambient temp. in Michigan. I have seen a lot of concrete pavement not upheaving at much higher temperature so is the temperature really to blame as shown in the internet video?

 

[concretemasonry]

It all depends on the temperature of the soil and moisture contents of the concrete and the soil.

We had 28 blow-ups on the freeways a day or two ago (and about a similar amount the next day) due to the temperature (103F) on the first day.

It is a classic problem of thermal expansion, temperature differential and restraint. the soil is cool and moist, but the surface layer rises in temperature quickly due to the air temperature and the radiant heat. Most of the "blow-ups" were minor and patched until traffic and weather was better.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[hokie66]

Was this continuously reinforced pavement? Where did you see the video?

 

[csd72]

Concrete doesnt expand that much percentage wise compared to some other materials but given enough length with insufficient joints this expansion accumulates into a problem.

There is also the curvature from the temperature differential as concretemasonry has mentioned.

 

[cvg]

it's not the air temperature that you should be concerned with, the pavement temperature can get much, much higher. Here in Arizona, they fry eggs on the pavement.

 

[hokie66]

Yes, but the pavement doesn't get that hot if the air is not hot. Expansion problems only occur in the hot time of the year...maybe it's hot all the time where you are.

 

[cvg]

pavement temperature is only partially related to ambient air temp. my point is that with an air temp in the shade of say 110, the pavement temp could be over 170. that has a significantly larger effect on the amount of thermal expansion.

http://www.pavement.com/Downloads/QDs/QD007P - Hot Pavement.pdf

 

[Ron]

One thing that significantly impacts expansive failure of sidewalks and pavements, is impaction of the joints. If the joints have no capability of expansion, because of sand or other debris filling the joint space, then failures can occur.

Keep in mind that the temperature differential that must be considered is the temperature at the time of slab set vs. the max. temperature the slab will see. If the concrete was placed in cool weather and then subjected to high ambient temperatures, the effect will be greater than if the initial temperature was, say, 70 degrees F, and the maximum concrete temperature was, say, 95 degrees F.