Cracks in new concrete?

[PoolCat200]

Hi! We have a new fiberglass pool that was just installed. The process has been an extended nightmare due to some permit issues, but we’re finally getting close to the end. However, our concrete pool deck was just poured Friday morning. By Friday afternoon we could see hairline cracks in a couple of slabs.

We are particularly concerned about the slab right near the pool steps as the cracks have spread across the slab. This area also appears rougher on the surface than the rest of the concrete. The concrete guys ran into trouble with the pour in this area because the pump/hose stopped working and they had to wait for another concrete truck. On the side of the slab you can also see an edge where the concrete from the original pour meets the newer pour.

Are cracks like these typical? If not, what should we be asking for at this point? We are pretty sure the pool builder/concrete people will just tell us that all concrete cracks and not to worry. We will try to attach photos. Thank you for any advice!

 

[PoolGate]

They say it is not "if" but "when" concrete will crack. Mine waited about 2 seasons. The hope is that it will crack along the stress relief joint but it frequently cracks elsewhere. That said, to have it crack before it is even cured is concerning. Do you have any pics of the area before the concrete was poured that shows the prep?

 

[PoolCat200]

This was after they filled with gravel and put down rebar.

 

[PoolGate]

Talk to your builder but mostly likely you will be told unless there is up/down separation or a gap over like 1/4" they will not replace it. Specifically inquire into the concrete warranty terms.

 

[pjt]

our concrete pool deck was just poured Friday morning.

Are you curing the concrete? It looks dry in the photos. Curing is essential for concrete quality and strength.

 

[kimkats]

Did they put anything under the wire/rebar to keep it off the ground?

Have you been watering it down at all?

 

[PoolCat200]

Are you curing the concrete? It looks dry in the photos. Curing is essential for concrete quality and strength.

We were not left with any instructions but are 99 percent sure the concrete subs used an add mixture to accelerate curing as they were able to remove forms shortly after pouring. When we first asked about the crack shortly after concrete subs left, pool builder advised us to water it down. We have been doing that about hourly as water evaporates off pretty quickly. Picture was just before watering down first thing in morning.

 

[PoolCat200]

Did they put anything under the wire/rebar to keep it off the ground?

Have you been watering it down at all?

We didn’t see them do anything to lift rebar up unless it was being pulled up as they moved it with their feet during pouring. Also, we have been watering down about hourly during the day.

 

[.ben]

We didn’t see them do anything to lift rebar up unless it was being pulled up as they moved it with their feet during pouring. Also, we have been watering down about hourly during the day.

Rebar laying on the ground as shown does absolutely nothing. May as well not have rebar at all. Any concrete contractor with more than 10 minutes of experience would know this.

Hand lifting (“hooking”) of bars during pour is not generally acceptable practice but some contractors will do it.

 

[PoolGate]

My deck has no rebar or mesh in it. They don't always use it.

 

[Bperry]

My deck has no rebar or mesh in it. They don't always use it.

Same for mine.

 

[PoolCat200]

Partial Update: Pool builder agrees the texture problems and cracks are not acceptable. Concrete guys are apologetic and blame the malfunctioning equipment (which we believe as we saw the issues they had and the first part of the pour looks great). They are coming back later today to assess and say they will make it right. Not sure what the options will be, but removing it/replacing or coating were briefly mentioned. Should we be concerned that jack hammering and removing the concrete may cause damage to the pool/plumbing? Is coating to fix the texture/look a bad idea if they think it is structurally sound?

 

[PoolGate]

Great news. Hopefully they remove the concrete and do another pour. Is it just the one section that is having cracks? Make sure your bonding wire doesn't get cut or disconnected when they do it.

 

[PoolCat200]

Update 2: Concrete company and pool builder are planning to remove and repour the slabs around the shallow end - about 30 percent of the concrete. Fingers crossed removing it doesn’t cause any other issues! (If project runs true to form so far it will…)

 

[kimkats]

Nice to see them doing the right thing!

 

[Toxophilite]

Great! You might have one issue show up. Different batch and different day pours can many times throw differently shaded cement color. Sometimes they eventually sun bleach to even color, sometimes they don't.

 

[PoolCat200]

Update #2: Cement company thinks the cement may have been a bad mix and wants to remove and replace the entire decking around the pool. Anything we should be on the lookout for/checked for damage once all the old concrete is removed? (Replacement rails for the autocover have been reordered and we know will be replaced.) Thanks!

 

[PoolGate]

Bonding wire!

 

[kimkats]

"chairs" under the wire to hold it off the ground this time. Some people use broken pieces of bricks. Does not matter so long as it is off the ground.

 

[Jaffles]

Yes for my money I'd be wanting chairs to hold the wire up off the ground. Pulling it up while they pour and walk all over the mix is slack and poor practice. I'd also want far more wire or reo mesh as we call it in Aus, and tied together where it overlaps. You could also ask them what MPa (Megapascals) strength of concrete is being used. 20 to 25 MPa at 4" thick would be a adequate and is pretty standard for paths and driveways. Should have enough strength with mesh to withstand some subsidence and hold its integrity.