The Brew Cabin

Tony:
My paving stone driveway is 10 years old and has developed tire ruts no more than 25 mm deep. The sub-base is 100 mm crushed stone with 35-40 mm sharp sand as the base and in the joints. The drive slopes gradually from the garage to the street and drains OK. The problem here in New Hampshire is what we call "frost heaves", where the ground rises during deep freezes and resettles when it thaws. Driving over that gradually creates slight ruts
Can I re-level the pavers with a vibrator plate (wacker) without removing the pavers? If so, wet or dry? Ocassionally, I'll lift pavers in an area, add sand, and level with a rubber mallet, but that's too much work to do over the whole length. Besides, the ruts eventually come back. Renting a wacker plate would be much easier, but I need to know if it will work or not. Or should I just learn to live with the ruts?

Hi Jerry,

there's no effective way to eliminate the ruts (known as channellisation) without removing the blocks. I'd suggest lifting up an area at least one block wider than the affected area, and taking a look at the sub-base layer. You may need to consider scraping out the bedding sand and topping-up the sub-base rather than keep adding sand.

If the sub-base itself is badly affected, it might be worth lifting the lot and putting in a separation membrane (see Geo-Membranes page) beneath the sub-base, relaying the sub-base, the bedding and then the blocks - not the sort of job you can do in an hour or two, I know, but probably more effective in the long term.

Anyway, assuming the sub-base is reasonable, and doesn't need to be excavated - add more sand to the bedding layer, lightly compact it with the plate compactor and then screed it out to level. Replace the blocks, brush in the jointing sand, compact the lot with the plate, and then treat yourself to a well-earned pint. :)

Try and find genuine jointing sand rather than using the same stuff that's used for bedding. The grain size really is critical to generating sufficient friction between adjacent blocks to help them carry the load. If, as you hint, they've previously been jointed with any old sand, then that won't be helping matters.

If the channellisation keep re-appearing, it suggests the sub-base is inadequate and may need to be replaced to below the frost limit, which will be what is known over here as a right bloody ball-acher!

Have you had a sealant applied to the blocks at all, Jerry? That can help reduce some channellisation, but I've not much experience of frost heave damage, so I can't swear it would be a definite help.

Hi Tony:
Thanks for your promt and informative reply. Yours is one of the few web sites where I can get detailed, expert advise; most others simply push their product as the answer to every inquiry. Although your answer wasn't what I'd hoped, it saved me the frustration of using the wacker alone and finding out that it doesn't work.
When the tarmac was removed before laying the pavers, we found the sub-base itself exhibited ruts. The contractor filled and leveled it before laying the sand bed for the pavers. I suspect it has happened again either due to soil pumping from the bottom or sand migration from the top; probably both. If I have it properly repaired, I'll have separation membraines laid on both sides of the sub-base.
I'll have to look for "jointing" sand. Bagged sand here is either smooth (play) or sharp (masonry). Contractors who buy bulk sand probably have more grades to choose from. I have applied solvent-based acrylic sealers (5 gallons @ &#3625 USD/gallon) twice, with unsatisfactory results. I have a hexagonal pattern in red and gray pavers. The sealer looks great for the first few months (the wet look deepens the red), but then the red pavers wear and fade unevenly. The acrylic coating gradually whitens. more pronounced in the surface indentations than on top of each red paver. I also sprayed it once with solvent alone with the same results. Based on your sealants page, polyurethane would probably be a better choice. Can that be applied over acrylic, or would I have to stripe it off?
The orginal contractor (from Portland, ME), the paver and sealant manufacturers (both from Montreal) are all out of business. And even with as little as I know, its more than the local suppliers and contractors I've talked to about paving stone driveways. So its likely to be quite some time before I'm confident about hiring another contractor to do a proper repair. (Over here we'd call that work a ball-buster.)
Meanwhile, I think I'll have a pint anyhow. (I like Samuel Smith Oatmeal Stout, when I can find it.)