Spalling of concrete gutter pans

[quark12]

In MD many roadway gutter pans are constructed of concrete many experience spalling. Does anyone have any knowledge on what might be causing this to occur and how nbest to fix it? The state specified concrete mix is being utilized.

Thanks

 

[ztengguy]

What do you mean by gutter pans?

 

[EngineeringEric]

Is it AE concrete? are their de-icing salts? troweled?

 

[cvg]

this is really not a structural issue, so dont expect a great response in this forum.
is it really spalling or could it be weathering or ASR or poor aggregate quality or damage from snow plows or road salt or something else? I would not expect spalling to be a big issue for a gutter. you need to do some investigation to determine the problem first. CTL or somebody like them could help with the testing and identification of the problem

 

[manstrom]

Salt on fairly new concrete is a recipe for spalling.

 

[hokie66]

Is there reinforcement in the gutters? Was an accelerant used in the mix? Air entrained?

 

[quark12]

Concrete has no reinforcement and is air entrained (5.5%). It was fairly new and poured a few months in advance of winter.

 

[manstrom]

I've read that a few months may not be enough time to prevent salt related spalling. I same across this when looking at concrete driveways. I know it sounds crazy, but I have seen a lot of spalling on new sidewalks after a heavy amount of salting last winter. I also recall reading that certain ice melters shouldn't be used on fresh concrete.

Here are a few references.

http://www.sakrete.com/media-center/blog-detail.cfm/bp_alias/Why-do-concrete-slabs-crack

http://www.xynyth.com/resource/icemelter-concrete/concrete-basic.html

Take it with a grain of .... salt.

It also may have to do with the amount of freeze / thaw that the surface saw.

 

[hokie66]

How were they finished? Hard trowelling of air entrained concrete often leads to scaling.