Concrete cure time before setting stone

[musclecarboy]

Guys, I'm doing about 220sf of india limestone wet laid over an existing concrete walkway. The concrete is solid but they wanted a curve removed and everything squared off (see pic, red is new). I poured it on Sat, how long should I wait until putting the stone?

[mrusk]

like a day

[CaptainsLS]

like a day

^This. On stone walls and CMU we have laid up materials the same day.

[MuirView Design]

As concrete cures it shrinks and tightens. That's why most things with concrete are a two part process. If you lay your stone too early on uncured concrete, it will shrink and pull away from the mortar under your stones and cause the bond to break. If you try and point the joints between the stones before the mortar under your stones has set up, you'll most likely develop hairline separations between your mortar and the stone.

We sometimes pour a footer for a wall in the morning and start laying block in the afternoon, but it depends on the humidity and temperature. I typically always wait till the next day before we start laying on a fresh footer.

BTW - are you removing that whole section of curve and cutting a clean joint for the new pour? Don't forget your expansion board and to carry that joint up to your limestone as well. You could always go the thinset / ditra membrane route if your concrete is pretty level and you're grouting the joints and not pointing them.

[tturbonegro]

wait a day or so and you should be fine...cut an expansion joint or 2 in it if you are worried about it moving

[mpickel]

It depends on the concrete used and temperature. I have done it same day in the summer and I have waited 3-4 days. I tend to err on the side of caution and wait a few days if it is too cold outside.