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lews 04-14-2010 07:43 AM

Need Help - Failed Patio in Sand Install
I have a pool that was installed on a hill. The excavations were spread around the pool to create the area for a patio surround. There was some rock in the pool and apparently this was included in the the fill for the surround.

A mason contractor then came in and laid limestone pavers (about 1 3/4" thick -- maybe 6x12 rectangle). The dirt is loose clay (sandy clay). It was laid in rock dust - a blue stone material we have around here (Chapel Hill NC) - it goes from 3/8" down to dust and is sharp edged. We also have decomposed granite (we call Chapel Hill gravel), which is what I'd expect for a base but it doesn't seem to be used.

Of course is has settled (now 2 years old). The contractor did come back a year ago and fixed some bad areas. This time he was mixing rock dust with cement and then relaying them. This helped but it still settled some. No polymeric sand was used. The edging is that plastic angle stuff with the landscape spikes (which doesn't work well with such thin pavers). The contractor wasn't bonded and he's now had a stroke ... out of the picture.

I'm pretty broke from the project and so I'm faced with fixing the mess. I'm not the young whipper snapper that I once was, so I'm going to have to do it in sections. I've read on Pave Tech how to do the job right and clearly it was not done correctly.

I think I know how to do this by starting all over (excavate for a 4" base and 1" of bedding sand - probably use geotex under the base - use 1" metal pipe for the bedding sand. compact fill, compact base, don't compact sand, compact pavers - use polymeric jointing sand, compact again.

But that's big, big job. And unless I buy a plate compactor, doing a section at a time is problematic. I've got a hand tamper.

So, does anyone have some suggestions on not so perfect solutions? If I relaid it and used a polymeric jointing sand, would that keep enough water off to prevent more settling? After 2 years, its got to be close to being fully settled. What about using cement with the rock dust, like the contractor did, along with polymeric sand?

Need some help.

Snav 04-14-2010 08:33 AM

Have pictures?
How much of a slope are you talking about?
Is there any sort of a retainment wall at the base of the hill or at the end of the pool area to give stability?

I have a feeling that your issue is overall settlement of the entire hillside that's been disturbed - not just the bedding that the pavers are nested in. So, you can fix and fix the bedding - but as the underground continues to settle or slide downhill then your problem will continue to grow.

Lack of a retainment wall will permit the hill to shift - the entire hillside, or sections, will slide downhill.
Untamped, or partially tamped earth will settle naturally - a retainment wall won't necessarily help this, this is just compression of the soil.

I'll let other's dive into your possible solutions - I don't have much experience in that area.

lews 04-16-2010 06:02 AM

Somehow my reply didn't get posted. I'm pretty certain it is not the whole thing moving downhill. The slope of the hilll is modest and the rough grade is conservative - ie, the slope of the downhill side of the patio fill is gentle. Also, the settling is spot settling, not the whole side (although there's a lot of spots).

lews 04-16-2010 07:05 AM

3 Attachment(s)
Here are some photos

GardenConcepts 04-17-2010 05:10 AM

From the pictures it look likes the pavers have settled below the edge of the pool coping. It also sounds like the fill around the pool is the culprit. If you use fill to build up an area intended to hold a patio, it must be a compactable fill, and compacted extremely well- using a double drum vibratory roller. Even then, the fill should be checked using a proctor test (checks for density) prior to installing the pavers.

In my opinion, you need to pull up the pavers and use a vibratory roller to further compact the base and fill. I would suggest contacting an engineer first. You'll need to be careful not to damage the pool when compacting.

lews 04-19-2010 06:34 AM

Okay. Thanks for the advice.

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