Concrete Expansion Gaps

[carlyai]

I've got this fairly big rectangular area to CPAC before I lay the tiles.

The CPAC will be about 3 inches thick, tied in with square mesh.

I think I will need expansion joints, to stop the cement from cracking.

I have some questions about the expansion joints.

1. If I use the strong mix CPAC (380 if I remember), and tie the mesh into the pool walls and fence walls, will I still need expansion joints?

 

2. If I put in expansion joints, they should go between the pool walls and the CPAC and across the CPAC from the pool walls to the fence at about 2 m spacing?

 

3. Can you include expansion joints in CPAC and then completely tile over the joint, or will the tile crack?

 

4. How should I CPAC the area to come up with a nice tiled finish (no cracks)?

 

Pictures:

1. The first pic. is between the pool and fence, all CPAC.

 

2. The second pic. is between the end of the pool and veranda area, which will be retiled out to the pool.

 

3.The third area is down the other side of the pool.

 

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[canuckamuck]

When you say CPAC, you mean concrete right?

[carlyai]

Hello, yes, sorry, the premixed stuff in the cement truck, locals refer to it as CPAC.

 

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[canuckamuck]

OK, I was just checking to see if there was some fancy product I hadn't heard of.

 

As far as your pour goes I would pour it in 2 to 3 meter wide segments leaving every other section unpoured. and then do the unpoured sections a couple of days later. That way the concrete will crack on the seams. But I am a complete hack and haven't done a job as big as what you are doing there. I am sure a couple of the more expert members will find your post shortly.

[carlyai]

Thanks canuckamuck.
I've done driveways with expansion joints before, but never tiled over them.
The area under the veranda is 3 m wide and didn't crack, but it's in the shade.
Most of the pool is in full sun with water one side, 20 cm walls, then the pour.
Pic of the veranda (to be tiled over) and the layout of the pool in full sun.


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[r136dg]

IMO I don't think I'd use any expansion joints on something like that. If you have to do the concrete in more than one pour leave rebar sticking out to tie into the next pour. If you give one slab the ability to move independently of another it's likely you'll have a crack in your tile down the road. What you may want to do is pour the concrete a little thicker, 3.5". The wire mesh is a good idea. The most important thing is all that fill (sand/rock) added after the pool was back-filled is compacted, really compacted. Wouldn't want settling after concrete's in. You could also hammer-drill rebar from the pool to the wall (which should be on a stable footing) every 16" aprox. 

These are just the things I would do if it were mine, opinions will vary. Good luck!

[canuckamuck]

It just occurred to me that you need to ask some question about who and how they are doing the tiling  before you pour. The guys up here who do tiling use a method which requires about 3 centimeters of mortar under the tile. Whereas the normal way would be to use a ridged trowel and apply about a centimeter of tile adhesive or mortar.

This obviously will effect the height of your floor, and considering you have a pool, the final height of the floor is important.

Also when they pour with the knowledge that they are going to do the thick style of mortar, they do a crap job of the surface because it doesn't matter in the end. But you can't use a ridged trowel on a bumpy surface.

 

[carlyai]

Thanks for the replies. I've talked to the tiler and the plan is to use the 380 concrete that we used for the pool floor and walls.

12 mm rebar in the pool walls, and all joining surfaces tied into the Y mesh.

[mention=213260]r136dg[/mention]

Yeah, an expansion joint will not work, and we will pour it all in 1 pour. We've already poured the pool floor and then the walls in 1 pour, so the team and CPAC company are used to us. [emoji3]

 

Pics. of the rebar to be tied into all joining surfaces.

 

Just started apoxying the rebar in.

Thanks for the replies.

 

Edit

@r136dg

 

The sides of the pool dug out were filled with crushed dust, same with most of the area. The sand is on top of the crushed dust already compacted once. Will do it again after the drainage and water pipes go in. Thanks for the reminder.

 

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[carlyai]

Thanks, we've got the tiles level with the veranda new tiles and about 1cm under the wall coping.

 

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[esprit]

And exactly to what concrete standards are you using ?  Have you verified the concrete quality and standard ? Have you asked for concrete cube tests after 24 hours/7 days and 28 days to ascertain that the concrete strength is as specification ? Basically if you have not you just get crap.  No worries upon expansion joints as the concrete will most likely  just deteriorate and cracks will develop.  Never mind as to whether the sub strata was prepared correctly or not.

 

You have to remind yourself that design life in the real world is 30 years minimum and often 50/100.  In Thailand it is 1 day after you have paid a "builder"/ cowboy their last payment.

 

Good luck to you but by asking the question now indicates your total lack of technical knowledge ( no problem there but you should use a civil engineer) but a ridiculous trust in Thai "builders"

[sappersrest]

The clue is in the forum heading, DIY, this forum as I see it,is to help people who  have no specific knowledge but are prepared for whatever reason to have a go at DIY in a safe manner.

 

[carlyai]

[mention=20134]spirit[/mention]

Loved your post [emoji3]

Here's the concrete specs, but I doubt you can read Thai.

I don't need a civil engineer, as I was a teacher and we know everything 555.

If it cracks, we'll do it the Thai way and fix it till it crackes again and fix it again.

 

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[carlyai]

Sorry can't seem to send CPAC

 

Oh they turned up.

specs.

 

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[carlyai]

Well it's been 5 days now and it hasn't cracked 555


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[canuckamuck]

Looks great, now I want one.

[r136dg]

13 hours ago, canuckamuck said:

Looks great, now I want one.

me too

[carlyai]

this looks even betterer. just started today. yahooooo.


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[r136dg]

Nice!

[barrywhite]

On 18/07/2017 at 0:24 PM, carlyai said:

Sorry can't seem to send CPAC

 

Oh they turned up.

specs.

 

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I often wonder has there ever  been even one note saying "fail"???

[barrywhite]

14 hours ago, carlyai said:

this looks even betterer. just started today. yahooooo.


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It's  quite a deep  pool.

[carlyai]

It's  quite a deep  pool.

Lucky SWMBO can swim, also just paid for the grandkids 10 weeks swimming lessons. Unfortunately only 1 day a week, but the can now swI'm.

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[bbradsby]

On 7/27/2017 at 11:50 PM, carlyai said:

Well it's been 5 days now and it hasn't cracked 555
 

don't worry, it will.. but, from your post, its clear you've got the right attitude. I can tell you're a LOS long-stander!

[carlyai]

@bbradsby
'don't worry, it will..'

.....no it won't [emoji41]

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