Originally Posted by Amethyst
We'd like to avoid the large expense of having the whole thing jackhammered up and a new walkway laid. One solution we considered, was to put down a new layer of concrete and embed flagstones in it. Not sure either of us is handy enough for such a large job, though. Would hate to invest the time, money, and effort, only to have it scream "Amateurs were here."
Anybody been in a similar situation? What did you do?
Funny you should mention this. We're in the middle of repairing our lanai/sidewalks, which also date from 1989.
An old 20'x20' outdoor lanai had been badly poured. The contractors said that there's just no way to put a thin layer of concrete on top to fix the dips & other problems without eventual shifting & spalling. So we had that jackhammered out and re-poured with the proper slope. During the demolition we found that a sprinkler line had been clamped off (plastic flex pipe, not PVC) and the water leakage had undercut the sidewalk. The ground subsiding under the sidewalk had caused it to crack. Our sidewalks have both cracked around the drain cleanout plugs from the kitchen/bathroom drains. One sidewalk slopes toward the house instead of away from it, and in less than 20 years rainwater has already effloresced the footing.
Concrete may not seem like rocket science but the contractors had a tremendous inventory of tips, tricks, special tools, and ways to work the concrete. No way we could have duplicated their experience, let alone achieved the proper slope and finish.
The rest of our sidewalks, lanai, and driveway had been covered in FuturaStone, which has no UV resistance and does not wear well in Hawaii sunshine. We've just had the FuturaStone scraped off to expose the bare concrete. Small cracks may be epoxied but bigger ones will be jackhammered out, the soil underneath stabilized & compacted, and repoured. They say that they have to "respect the cracks" by following the expansion joints and stabilizing the cracks-- or else the stamped concrete will eventually crack in the same way. After the concrete has been pressure-washed and etched, it'll be covered with an inch or two of stamped concrete.
Now that the FuturaStone is no longer hiding the concrete, we can see that one section of our sidewalk had been jackhammered out to connect a sprinkler line to the municipal/house water line and then repoured. The replacement concrete is darker, sandier, and eroding just from scraping tools across it. The contractor said it was poured from a Sacrete mix (too much sand, not enough cement) instead of a concrete mixer or a concrete truck. They're not sure that they're going to be able to salvage it-- easier to just repour the "correct" way instead of with "amateur" work.
One of our covered lanai has a round patch about three feet in diameter that's also a different consistency than the surrounding concrete-- again a bag of Sacrete dumped in by an amateur. The difference is that it's covered by a roof so there was no rainwater or other weathering. The contractors think they can live with that one. I'm wondering if we need to scope it with a metal detector or a ground-penetrating radar before we cover it over...
The issue with your cracks is that the ground underneath may be moving (or frost heave?) or the concrete may be losing its strength. You may have sewer/drain/sprinkler pipes underneath that could be moving or even collapsing. If you put more weight on top of everything then you'll just accelerate the motion/decomposition.
Spouse and I have talked about our concrete job for over five years and we spent a lot of time figuring out what we wanted. The contractors have been hugely busy during the housing boom but the recession is making the selection (and the price) much more "affordable". If you decide that you're going to continue to have a sidewalk there then I think it's worth consulting a contractor or two who've done soil stabilization and foundations, who may have the experience to diagnose what's causing the problems with your sidewalk, and the best way to fix it.
Otherwise you'll get to fix it every few years!