To clarify this was to get within 6" of the final surface, not sure what was going to be directly under the 4" thk slab.
Cracks in concrete deck, Opinions please!
- Thread starter Bart
- Start date
OK, concrete guys... I have a (slightly threadjacking) question. How can the highway crews slice out 20'x50' sections of a concrete interstate highway at 1:00 AM, pour in fresh concrete in the holes, and have it good to go for traffic by 7:00 AM drive-time commute?
That's on-topic, right? right?
That's on-topic, right? right?
I can tell you that this is EXACTLY what they used for my concrete deck also. Here is the result of that:
frost-heave-thoughts-please-t28747.html
frost-heave-thoughts-please-t28747.html
Ohm_Boy said:
Because you're in Orlando where they can get way with that
You cant have concrete highways like that in freeze country. I-495 was done that way in Massachusetts back 25 years ago. The entire 100+ miles of road has been replaced with asphalt over that last 7-8 years.
We have a similar problem here in North Texas, but not because of freeze/thaw. Our problem is expansive clay. Anyone who has driven the George Bush Tollway South from LBJ will directly experience the problem. It is like driving on a roller coaster...bk406 said:Because you're in Orlando where they can get way with that
You cant have concrete highways like that in freeze country. I-495 was done that way in Massachusetts back 25 years ago. The entire 100+ miles of road has been replaced with asphalt over that last 7-8 years.
But back to pools...I have a heaving deck around my pool from expansive clay. The soil was obviously not prepped properly, but is that even possible with highly expansive conditions whether from freeze/thaw cycles or expansive soil? That is what I'm dealing with. Meaning, when redoing my deck with either concrete or pavers, how do I trust that the installer will do it correctly? Seems like a crapshoot...
You just have to do your homework and watch them.
To do a deck properly, you really need to remove 18 inches of the "bad" material and add back the proper stuff. I know that it's popular advice here on TFP to use stone to backfill pools and to use for the sub surface for decks. However, thats really not the proper material to use for the upper sub surface. Folks in areas that do not have deeper ground freezes may not have issues, but in general pure stone is not what should be used as an underlayment.
To do a deck properly, you really need to remove 18 inches of the "bad" material and add back the proper stuff. I know that it's popular advice here on TFP to use stone to backfill pools and to use for the sub surface for decks. However, thats really not the proper material to use for the upper sub surface. Folks in areas that do not have deeper ground freezes may not have issues, but in general pure stone is not what should be used as an underlayment.
How do you compact the soil surrounding a pool without damaging the plumbing? And how far beyond the actual deck should soil be removed/replaced? Sorry for the hijack, should have started a new thread... 
Beez said:
I would think pipes would be deeper than a foot or so. You would only be compacting 18 inches and I wouldnt think a plate compactor would do any damage.
Re highway patches: They use high early strength concrete that can achieve upwards of 3000 psi in less than 24hrs. This is usually comprised of type III portland cement with a very low water/cement ratio and a super-plasticizer so they can work it. I don't know how they consolidate it. I don't think it lasts as long as the slower curing process but it gets the traffic moving.
Re stone: #57 or 3/4 stone is generally considered to be self compacting by engineers. Whenever we find a stump hole or areas where the developer has dumped unsuitable soil in someones backyard, its what the engineers always spec to remediate the situation. It is also used to facilitate the movement of water under concrete structures, which is why its used under pool shells when you hit high water tables. Its a good underlayment for concrete slabs provided the water it can collect is vented to gravity. Crusher Run/ABC/Road Base is pure stone thats been crushed and run without washing or seperating the different sizes. It is a very commonly used underlayment for asphalt and concrete. It has to be consolidated and lifted prior to paving. Processed Pit Gravel has some soil in it and is used around here for residential and light commercial applications such as slab on grade buildings. It is cheaper and the quality of the material generally isn't acceptable as a road base. Its what the quarries call dirty rock.
Re stone: #57 or 3/4 stone is generally considered to be self compacting by engineers. Whenever we find a stump hole or areas where the developer has dumped unsuitable soil in someones backyard, its what the engineers always spec to remediate the situation. It is also used to facilitate the movement of water under concrete structures, which is why its used under pool shells when you hit high water tables. Its a good underlayment for concrete slabs provided the water it can collect is vented to gravity. Crusher Run/ABC/Road Base is pure stone thats been crushed and run without washing or seperating the different sizes. It is a very commonly used underlayment for asphalt and concrete. It has to be consolidated and lifted prior to paving. Processed Pit Gravel has some soil in it and is used around here for residential and light commercial applications such as slab on grade buildings. It is cheaper and the quality of the material generally isn't acceptable as a road base. Its what the quarries call dirty rock.
renovxpt said:
That's the base matetrial of choice up here for concrete patios, concrete pool decks, and pavers. Actually, both Unilock and Belgrade recommend it as a sub base. When compacted, you can walk on it and not see a foot print at all, yet it drains pretty well. The problem with pure stone, especially under pavers, is that the 4 inches of sand or stone dust you use to lay the pavers on tends to work its way down into the stone, even if its compacted. Granted, pure stone will drain a tad better than processed gravel, but with the gravel, the sand on top will not shift as much. Morevoer, if you have frost heaves in the pavers, they will usually sit back down if you used processed gravel.
Like renovxpt said, its not used under high traffic road beds, but sometimes they do use it mixed with asphalt millings. When that goes in, it gets hard as iron when rolled out.
Around here we didn't have "processed" pit gravel until 8-10 years ago, it was just pit gravel. It was decomposed granite that could be dug up without blasting. Prior to road specs changing in the 60's it was widely used as a road base. Most of the pits were closed and then reopened in the 80's mainly because of all the slab on grade houses and apartment buildings being built. It also became very popular for landscape walkways and "primitive" trails in parks and greenways because of its nice texture and color. That supply has dwindled and now the granite quarries offer the "processed pit"
Hey folks -
I'm going to try to re-hijack this thread back to my original issue!
I spoke to the builder who sent his concrete guy out to take a look at my cracks. The concrete guy originally thought it was a "bad batch" of concrete when he looked at the photos. I never heard what he thought after looking at the site, but the builder told me he was going to dig it up and replace the concrete.
I told him that I thought it looked like a (lack of) compaction issue because the crack was essentially in a straight line and was right above the pluming trench. He said the concrete guy "does not believe it was a compaction issue based on the fact that job was delayed for a period due to the county inspection delay so the ground had plenty of time to stabilize". This is true - there was a 2 month delay from when the gravel and forms were put in place until they poured the deck.
My question for the pros is, does that really matter? If the soil was not compacted at all, or not properly compacted would a 2 month delay do anything to stabilize the soil? Or is he just feeding me a line to cover for his subcontractor?
Thanks,
Bart
I'm going to try to re-hijack this thread back to my original issue!
I spoke to the builder who sent his concrete guy out to take a look at my cracks. The concrete guy originally thought it was a "bad batch" of concrete when he looked at the photos. I never heard what he thought after looking at the site, but the builder told me he was going to dig it up and replace the concrete.
I told him that I thought it looked like a (lack of) compaction issue because the crack was essentially in a straight line and was right above the pluming trench. He said the concrete guy "does not believe it was a compaction issue based on the fact that job was delayed for a period due to the county inspection delay so the ground had plenty of time to stabilize". This is true - there was a 2 month delay from when the gravel and forms were put in place until they poured the deck.
My question for the pros is, does that really matter? If the soil was not compacted at all, or not properly compacted would a 2 month delay do anything to stabilize the soil? Or is he just feeding me a line to cover for his subcontractor?
Thanks,
Bart
Wire mesh, IMHO, is not going to do much. They need to address the soil in that area. Chances are they just backfilled over the plumbing trench and graded for the deck. The trench was most likely not compacted, so you had a failure.
They need to compact and fill the trench this time. Most decks I remove have the wire mesh stuck to the bottom of the concrete! It really needs to be up in the middle of it to do any good, and most concrete guys don't make that happen (at least around here). In the end, mesh (or even rebar) will not prevent cracks from poorly compacted soil.
They need to compact and fill the trench this time. Most decks I remove have the wire mesh stuck to the bottom of the concrete! It really needs to be up in the middle of it to do any good, and most concrete guys don't make that happen (at least around here). In the end, mesh (or even rebar) will not prevent cracks from poorly compacted soil.