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I have just had a backflow valve installed in the basement. The man had to chip away some of the concrete, he then put new cement down. He also had to do some work outside around the foundation, he installed a pvc pipe as a weeping tile. This was Tuesday morning the 26th June 2014.

We had a lot of rain that day. last night I noticed there was a lot of moisture on the cement in the basement. How long before we have to wait for it to cure and is this normal. We do get lots of humidity in the house. I forgot to mention this was put on top of mud. This is in Canada.

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Concrete will never fully cure; it continually hardens forever, although for all practical purposes, it reaches a point where further hardening will be so slow as to unnoticeable.

Unless the mix has retarder (or some cement replacement material) in it, it will generally be hard enough to walk on in less than 24 hours.

Mixes are usually specified with a design strength - the compressive strength that the concrete will reach in a period of time, typically 28 days. As a general rule, at 7 days it will have reached around two thirds to three quarters of the design strength.

Don't worry about the water on the new concrete - it will help the concrete cure if it is kept damp after the initial set. The early stages of concrete curing is the hydration of the cement in the concrete.

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It depends on the composition of the concrete mix, water content, and temperature. Generally, concrete sets in 24 to 48 hours allowing for you to walk on it and partially cured within a week (keep the cement free and clear of heavy equipment during this period) at which you can continue building/construction. Most mixes fully cures at 28 days.

Refer to the manufacturer's packaging/site for instructions regarding the curing of its product, otherwise follow the above timeline for most mixes.

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In short, concrete takes 28 days to fully dry or cure. The rule of thumb is that you’ll need to allow the concrete 28 days of drying time for each inch of concrete thickness if the slab is under ideal drying conditions (an enclosed area with the HVAC on, meaning there’s air circulation and a low ambient relative humidity).

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  • I think you're conflating two different issues: "curing" and "drying". Concrete must be wet to cure, but it may remain wet after it's fully cured. The drying speed will depend on humidity, thickness and air flow; the curing speed won't.
    – Daniel Griscom
    Aug 23, 2019 at 15:17
  • You want concrete to stay moist until it's cured. Notice that concrete remains a zero tensile strength powder until water is added; water is essential to the bonding (hydration) process. If dried out too early, the concrete will be weakened. cement.org/learn/concrete-technology/concrete-construction/…
    – Technophile
    Jul 9, 2020 at 15:17

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