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Mortar Flaking, Scaling, Pop outs in new concrete sidewalk
2

Mortar Flaking, Scaling, Pop outs in new concrete sidewalk

Mortar Flaking, Scaling, Pop outs in new concrete sidewalk

(OP)
I am looking for a guidance document for determining if new concrete sidewalk that has either mortar flaking, scaling, or popouts should be removed and replaced? Is there guidance for the percentage of each square that exhibits each of these problems? I have read that mortar flaking and scaling are generally considered as a cosmetic issues. Is minor to medium scaling of concrete sidewalk generally accepted at bond release?

RE: Mortar Flaking, Scaling, Pop outs in new concrete sidewalk

Tough question. Depends on extent & depth of damage. I suppose it mostly depends on project specifications whether you have a clear case to say "you didn't meet specs, you must repair or replace".
Those defects are a sign something was not right with the mix, placement, curing, etc. Have there been freezing condition since it was placed? Use of salts/deicers?
salt used? There are probably methods to check if there is widespread surface weakness, such as with a rebound hammer.

Some good points are made at the below link where there were similar defects; in that case likely due to a wet mix, being worked when wet, resulting in excess water & paste, lower strength, and lack of air entrainment near the surface.

https://www.reddit.com/r/Concrete/comments/u23by9/...

RE: Mortar Flaking, Scaling, Pop outs in new concrete sidewalk

(OP)
What is your source for evaluating extent & depth of damage?

This sidewalk is located in a major subdivision in NJ. Site improvement is NJ are governed by the Residential Site Improvement Standards, which require the use of NJDOT Type B concrete (which is air-entrained). The concrete tickets did not show air-entrainment (I was not involved when the tickets were submitted). Without air entrainment, the concrete is less durable and more susceptible to freeze/thaw and deicing effects. We would be going to court at this point if we rejected all of the concrete because it was not air-entrained.

I do not have experience with rebound hammer testing. Would cores be needed for calibration? ASTM C805 states that rebound hammer values cannot be used as the basis to accept or reject concrete. It could be used to determine if further testing is needed. Petrographic testing would be the next step, but that is expensive. The combination of the rebound hammer testing with petrographic testing is likely what we will require on the questionable sidewalk sections.

RE: Mortar Flaking, Scaling, Pop outs in new concrete sidewalk

Pop outs... ASR?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: Mortar Flaking, Scaling, Pop outs in new concrete sidewalk

For rebound hammer testing, you need cores to correlate the results.

Did the field tests show air content in the acceptable range?

If the concrete was specified to be air entrained, and it was not, it should be a short court case.

RE: Mortar Flaking, Scaling, Pop outs in new concrete sidewalk

Attached is an article from MRMCA about scaling. From what you describe it sounds like improper curing. New concrete shouldn't be scaling. When was it placed? I'm surprised the concrete doesn't have AE. Unless your spec called for AE you can't make them replace it. However, check to see if the spec has a requirement to repair surface defects or a warranty. Without a repair or replacement it's only going to get worse.

RE: Mortar Flaking, Scaling, Pop outs in new concrete sidewalk

It's not acceptable, but not the worst thing in the world. As long as the sidewalk is safe to walk on (or wheel a wheelchair on), it can be ignored. But tell that to the person who paid for the sidewalk!
I saw a notable case at one of my buddy's houses. I think the driveway was poured in November, and being in the Midwest, there was snow, and salt was applied. It wreaked havoc with the concrete surface. I can't imagine the concrete was not air entrained, but maybe that had something to do with it.

RE: Mortar Flaking, Scaling, Pop outs in new concrete sidewalk

If they sprinkled excess water on the surface during finishing, the concrete is likely to flake and spall, also.

I've always been taught that the best concrete should not have de-icing compounds applied during the first, and preferably second, winter. Try and get a property owner to agree to that.

RE: Mortar Flaking, Scaling, Pop outs in new concrete sidewalk

Can they put a sealer on it? Like silane or siloxane? Maybe time to do a petrographic series of tests, just to see what you really have.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

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