If concrete is still fresh (about 2 to 4 hours after pouring), it is important to cover the surface to protect it. However, once the concrete has been finished (between 4 and 8 hours after pouring) and has hardened enough to walk on it, the effects of rain should be minimal. Even if it starts to rain after a concrete pour, the possibility of damage may not be so serious. If you had time to complete the finishing process and the concrete has hardened (usually 4 to 8 hours after mixing), rainwater may cause little or no damage. It usually takes 24 to 48 hours for concrete to dry enough for you to walk or drive on it.
However, the drying of concrete is a continuous and fluid event, and it usually reaches its full effective strength after about 28 days. Concrete can take 24 to 48 hours to set and about a week to partially cure. During this time, walking on the surface is allowed. However, due to the nature of the consistency of concrete, it is better to avoid heavy equipment during this period.
This will ensure that there is no damage to the surface. In general, concrete can take 28 days to fully cure, however, it continues to cure indefinitely throughout its useful life. The fact that it starts to rain during or shortly after a concrete pour does not necessarily mean that your project is doomed to failure. It all has to do with time and at what stage of the curing process the concrete is. If rain occurs when concrete is cool (approximately 2-4 hours after mixing), the surface must be protected from rain. If the finishing process was completed recently, rainwater may not cause damage, as long as the surface is not worked and the slab is not touched.
If the concrete has hardened to the point where it is ready to groove and grind (usually 4 to 8 hours after mixing), rain damage is no longer a concern. The biggest problem you may face is the effect that rain may have had on the concrete surface. If it was not covered before the onset of rain, if the hardening was not very advanced at that time, and if there was enough rain falling hard enough, the rain may have washed away some of the cement from the concrete. It would be left with a weakened surface and the possibility of related problems in the future. They may include surface dusting, an unsealed surface that will allow much more water to be absorbed, and a reduced ability of the slab to resist cracking due to freeze-thaw cycles. But the most serious consequence could be peeling of the surface, especially if it was heavy rain.
The result is a concrete surface similar to the scaly layers of a croissant. You will often see the scale right after a storm, but sometimes it is not visible until the slab has had some traffic, when the scale breaks or falls apart. If you haven't paid for your yard yet, this would be a reason to try to get a one-year warranty for the work of the contractor who installed it. If problems arise as a result of problems on the surface left by heavy rain, you will be covered. If there is a heavy downpour and too much groundwater gets into the concrete, it will weaken.
Unless you pull out the concrete and start over, the best remedy is to remove the weak surface layer by grinding and then re-coat with an overlay, after making sure that the underlying concrete is structurally sound. This is because extra water can be absorbed by fresh concrete and change its water-cement ratio. Gravel is especially important in clay soils because it does not drain well, which causes water to accumulate under the concrete slab and slowly erode away at soil as it eventually drains. If it's not wet but your finger leaves a slit in newly laid concrete, then you should cover it because raindrops can mark its surface and excess water can reduce its strength. Heavy rains after a concrete pour can be of concern if it has not been finished and had enough time for initial curing process. While dry weather and smart planning are always recommended for any new concrete installation, they are not essential. Checking weather forecast before pouring concrete, preparing accordingly if doing so independently are key steps in ensuring successful installation even in case of heavy rainfall.
Heavy rainfall can cause problems for freshly poured concrete, as it can remove some of cement from mix. Unless you pull out concrete, best remedy for weakened surface due to excessive water absorption is grinding followed by re-coating with an overlay. Heavy rains after a concrete pour can be concerning if finishing process hasn't been completed or curing process hasn't had enough time yet. Dry weather and smart planning are always recommended for any new concrete, but they are not essential if proper steps are taken before pouring. .
