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-   -   Expected paver settlement on sand (http://www.diychatroom.com/f16/expected-paver-settlement-sand-46013/)

istokj 06-05-2009 10:25 AM

Expected paver settlement on sand
 
Hi.
I am installing concrete pavers on a 6" base of compacted gravel with 1-2inch sand on top. The problem is that i need the top of the pavers to end up flush with an adjacent concrete sidewalk. I am setting the pavers over uncompacted sand about 1/2 inch above the sidewalk and will use a plate compactor to settle them (i hope) down to the sidewalk. So i have two questions:
1. How much will concrete pavers (4x8x2 3/8) settle when you run a plate compactor over them ?, and
2. If they dont settle enough will i be able to pry them out, remove some sand and re-set or will they be locked in too tightly to move (does it matter if i put polymeric joint sand into the joins before i compact them) ?

thanks for any help !

Daniel Holzman 06-05-2009 10:50 AM

There is a much easier way to accomplish what you want. Since you are compacting the gravel, it will not settle at all. The sand is only two inches thick, so if you compact the sand, it will not settle either. Simplest, best technique is to place and compact the gravel, then place a small area of sand, compact it, then place a couple of pavers so that the top of the paver is flush with the adjacent sidewalk (or perhaps 1/8 inch at most high). You can wiggle the pavers a little to get them to be exactly flush. Now you know how much sand you need, so place the same amount of sand over the rest of the gravel, install pavers, you are good.

It is not necessary to plate whack the pavers if you compact the sand first. In my experience, plate whacking the pavers risks breaking them, and all it does is indirectly compact the sand under the pavers (but you already compacted that sand, so it is not necessary).

istokj 06-05-2009 12:11 PM

pavers and sand
 
I appreciate the idea and i like it but.... all the paver manufacturers say to place the sand uncompacted, add joint sand, and then use a plate compactor to settle it all before adding more joint sand (even folks on this site say this) so i am a little confused. I have a few hundred installed with perhaps a thousand to go so i need to figure out what to do by this weekend. I can either pull them up, compact the sand and re-set them as you suggest or try compacting them and then adding or removing sand beneath blocks of pavers as needed..both options seem painful !

Daniel Holzman 06-05-2009 02:30 PM

I understand that the paver sites generally recommend running a plate compactor over the pavers. This is done to compact the sand beneath the pavers, obviously the pavers themselves do not compact, since they are concrete, brick or stone. When we did our walkway (brick), we compacted the sand, then placed the pavers. It worked fine, the walkway has been in place for 15 years, no settlement, no problems.

There is nothing wrong with compacting over the pavers, other than you might break a paver or two, but in your case you are trying to achieve a very specific goal, namely matching an existing walkway. If you are uncomfortable deviating from manufacturer's recommendations in this case, perhaps you can place the outer band of pavers (the ones that need to match) by compacting the sand first, and place the inner pavers by compacting with the plate compacter. I think you will find the end result is the same, but post if it turns out differently.

As an option, you can place a test line of pavers on uncompacted sand, then measure the compaction when you run over the pavers with the whacker. Once you know the compaction amount, you can set the sand grade appropriately.

melissamarie9 06-10-2009 04:59 PM

We also laid our pavers the same as Daniel suggested. We put down our patio meeting up with a concrete pad. It has been a year and they are still looking great. I would suggest compacting the sand, laying the pavers and then place the locking sand in the joints.

concretemasonry 06-10-2009 07:45 PM

The sand setting bed should be a UNIFORM 1" thickness and UNCOMPACTED. You cannot compact a sand that meets the specifications. All compaction should be concentrated on the base as you shave it to a smooth surface the allows you to use a uniform sand thickness. If you want a slope for drainage, the base should be sloped so you can maintain a uniform thickness of the setting bed.

The purpose of using a plate vibrating compactor is to draw sand into the joints from above and below to insure a uniform, strong, even surface and to give the surface layer stability and strength so it can spread out the loads to larger area of the base material.

On a patio, you can get away with a few deviations. Polymeric sand is permissible, but it is never used on more critical installations like streets, roads, airport taxiways and ship unloading facilities were you have real loads.

Dick


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