Wetdog,

I just went out to clean the pool and decided to share a couple of pics of our concrete job. We also have some hairline cracks on the coping, which we used for the entire perimeter, and a couple of others around the deck area. None are "Too" disturbing, but as I have read on this site, I just accept them as part of using concrete.

I have included pictures of every crack I have found on my decking. Really, being so close to the beach and being on sandy soil, it does not seem too bad to me, but I am no means an expert. I would really appreciate some other opinions as well! All but one of the concrete cracks appears around the difficult angles of our grass area. The other is from the house to the skimmer.

Generally, no one notices the cracks and still compliment the backyard. So what can you do? Unless there is a flagrant issue that someone notices, I guess I will live with it and hope for the best. By the way, I think that staining will only emphasize a crack the same way water highlights them.

Good luck, and I'm also looking forward to any comments.

Regards,

Mike

Mike, thanks for the reply.
I had followed your build and growth of kids!!
Your pics and a few others steered me towards the pour in place coping.

It's funny, you see some jobs and there is no cracks then mine has many. Although they are extremly small (hairline) at this time I wonder if they will spread?

I also found your reply to someone asking about cracks.

I have a large brick paver patio that I had installed a few years ago and did not want it to look busy so I chose concrete for the deck and cabana area.

I will try and post a few pics.

Thanks!!

Oh yeah, I'll see you at the big one!!
This will be the worst wildland season on record!!

Wetdog

i was just about to start a topic on this. i have been swimming for three weeks in our new pool. the cracking started in the corners of our deck and now are following the cope and have circled the pool. some are hairline and some are a little more noticeable. they hadn't done the final paint on our deck and the guy says he is going to caulk them before he paints. i think the deck is still settling and this will be a reoccurring problem. i guess the question is how much is too much. it sucks to have a brand new pool with tons of cracks in the deck.

If you don't have expansive soil it could be the concrete contractor or the pumper added to much water. You can get receipts from the concrete company who delivered the materials.

There's an old saying by builders and concrete guys: there are two types of concrete: the kind that has cracks, and the kind that will have cracks :)

Concrete shrinks as it dries - not much - only about 1/8 to 1/16" per 10 feet, but since it doesn't stretch at all, you get cracks. Control joints keep the cracks hidden - usually. Remesh and Rebar keep the concrete from sinking and shifting. But the tiny little stress and shrinkage cracks are just about unavoidable, particulary with concrete that is poured on fill - and every pool deck by its very nature is built on fill.

I had one of the very best concrete guys that I know do my pool deck. He does great work, but I've got some tiny cracks in my deck, just like yours.

Hi,
I'm about to have my deck poured. what should I look for if anything when they are pouring or about to?
How about adding some fiber mesh that I hear/read about in this forum? How much is that and does it help?

thanks in advance,

Mine is two years old and I have only one hairline crack. A contractor told me to minimize cracks have joints every 5 feet on center. I do see alot of cracks in the joints, but only one minor outside the joint. Also, I used rolled wire and fiber mesh. I really would ask them to add as little water as possible to the mix. It comes premixed from the factory, but sometimes the workers add extra water. That happened in another area where my boat is and there lots of cracks.

Thanks for the insight. Quite a few people dealing with this!!

Just had the concrete supplier out to look at the job.
He stated a design flaw.That because of the curves it cracked. My pool is freeform and has many curves, basically it is all curves. He stated fiber mesh may or may not have helped. He said he sees 2-3 a week of these and it is very unfortunate. I was considering having my installer replace but the supplier stated it is normal and within industry standards and it would be at my expense. He mentioned splitting the cost with the installer and replace adding mesh, but once again 95% chance of cracks even with the mesh.... Jeez

Wetdog,

A lot of good insight, but I thought I'd add a few notes. In the concrete business, cracks are certainly very common. The pictures Mike posted show primarily shrinkage cracks, which are a result of the shrinkage previously noted in another post (~1/8" in 10'). Control Joints or saw cuts are meant to relieve the stress from shrinkage by allowing the crack to occur where it is more cosmetically acceptable. One of his pictures shows a classic condition on a re-entrant corner - this detail creates a lot of stress (because the concrete is shrinking in two different directions). The only real solution I'd suggest here is a saw cut or control joint on a diagonal. The picture of the drain shows what we call a "restraint to shrinkage" or RTS crack. Here, you would need to put a diamond or similar shaped cut around the drain with diagonal "spokes" around it.

Shrinkage cracks can be minimized by limiting the amount of water in the mix (with or without chemical admixtures to assist flowability), and by proper curing. Water curing is most common in residential construction, but can be tricky in terms of the surface cosmetics (if water pools in an area, the conrcete can be lighter in color).

Some of the other very small cracks that show up when your concrete is wet (they look like the surface of a dry lake bed) are what some call "hazing" or "map cracking". These occur while the concrete is still in its plastic (wet) phase. These are the cracks that fibermesh can be affective in handling. The fibers tend to hold the cement matrix together during the curing process, but are not nearly strong enough (too low tensile strength) to prevent the shrinkage cracks I spoke of above.

So while all concrete cracks, I'd suggest the following:
- never allow them to add water to the mix on site
- request a mix with the least amount of water possible "low w/c ratio" in concrete speak
- make sure control joints or saw cuts are properly laid out to relieve stress from shrinkage
- properly cure your concrete (ask about curing compounds like Confilm that will not affect color)
- consider fiber to prevent map cracking/hazing

mzenblu, great suggestions. I agree shrinkage cracks.
I wonder if the installer wet down the gunite,as the coping was poured in place without me being home.

I am at the, should I have them replace at my cost??

Does coping have/need rebar??

20k dollar job and my coping 16"x3' sections have 1-3 hairline cracks. The deck and cabana concrete still has not been poured.

If I rip out it may break some glass tiles. that opens another mess of trying to match different dye lots of glass tile.

Thanks
Wetdog

Wetdog,

Sorry for the slow reply - out of town most of last week.

Evan if the coping had rebar, it would proably still crack. Rebar is not meant to prevent these "aesthetic" cracks.

If it was me, I would look at what other cosmetic repairs are possible short of R&R (repair/replace). A properly color matched epoxy might be worth looking at. If you have Cool Deck, the repair can be covered by the acrylic coating. If it is exposed concrete I'd be more hesitant.

I've seen some guys that are really good with exposed concrete repairs, but I'd insist on seeing thier work elsewhere first.

Hope you find a solution that works for you!

mzenblu-We have a HUGE (25' long by 10' deep by 10' wide) that will have to be back filled because they had to relocate our pool, the day before the gunite. They are trying to convince me that conrete will be fine, but I am sooooooo afraid. I am going to have to pay to add the sonotubes, but still have other issues too. They didn't get the height of the pool right either, so we have drainiage issues and pitching issues on top of it. Do you think I am wise to give up my 'dream' of having this beautiful stamped concrete deck (also a concrete border to look like stone coping) for pavers? Pavers can be removed, concrete is a different story. I also asked for rebar or wire mesh, but they said it wasn't necessary. They also said that about the sonotubes, and a terrific PB that has taken me under his wing (thanks Brent!!!!) told me we need the sonotubes, the rebar along with the fiber mesh. Today they told me I could 'add' the wire mesh at $1 per square foot, and that it 'wouldn't hurt.' My $8.50 per sq ft stamped concrete is about at the $13 per sq ft mark with all of the extras, and that doesn't include the sonotubes. What do you think?

As far as everyone else with their concrete issues....I am truly sorry. I know how much all of this has taken a toll on me. Our dream backyard has turned into a nightmare. I wouldn't wish it on anyone. I just keep telling myself that my children are healthy, and sooooo many people have a lot worse tihngs to deal with besides a disasterous pool, so life is good.

jblairgolf,

Wow - that's a lot of fill. My experience has been that to be successful, this would need to be carefully compacted in "lifts" (layers of soil) that vary in thickness depending on your soil type (probably 6-12" range each). Even then, and even with the piers/sonotubes, there is no guarantee that the concrete will not crack. Rebar/wiremesh will not prevent cracking. Proper location of control joints is your best bet to control cracking by choosing the location where you would prefer for them to occur.

If it was my yard, I would go for the pavers.

If you choose to go w/ concrete, I'd ask them to spend an extra $300-400 on a soils engineering consultant to verify compaction ratios during the fill process - but again, there are no guarantees.

Best regards,

Mzenblu

Mzenblu-Sorry for the delayed response....pool issues to deal with..imagine that. lol. They are not using soil, but crushed rock. What do you think of that? They also repeatedly told me sonotubes are not necessary.

jblairgolf,

Crushed rock, compacted in lifts can make for very good fill material and would be preferable to using the native soils.

The only time I would look at sonotubes would be to create a pier system for expansive soils - essentially you pre-expand the soils around the piers/sonotubes with water, and the flatwork just bears on the piers (the soil acts as more of a form, but is not relied upon to provide structural support. This tends to be an extremely expensive solution!

I am fine with the crushed rock fill; but again would want a soils consultant to specify the depth of each lift, compaction ratios, etc. Proper spacing and location of control joints is the real key to preventing/minimizing cracks occurring where you were not planning on.

~Mzenblu