Although most of the hydration process takes place in the hours and days immediately after pouring, the concrete needs 28 days to completely dry. While the slab will harden and lighten in color within 28 days, don't be fooled into thinking it's done hydrating. If you plan to stain or paint the concrete, doing so before the process is complete may cause changes in the color of the stain or the paint to peel off. Summary The curing time of concrete takes about 30 days to fully cure.
Differences in climate, mixture and other elements may slightly change the curing period. The general rule of thumb for concrete drying is to dry 30 days for every inch of slab thickness. Most new concrete spills can handle foot traffic in approximately 24 hours. Most new concrete spills can handle vehicle traffic within 48 hours.
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. You can apply a curing product, such as Quikrete Acrylic Concrete Cure & Seal, to the surface of the freshly finished concrete to prevent water inside from evaporating and causing the concrete to dry too quickly. The test uses sensors inserted into the concrete at specific depths to measure the relative humidity of the air trapped in the concrete.
Your concrete should be solid enough to walk, without leaving traces, after 24 to 48 hours. Keep in mind that adding water to the surface does NOT mean adding water that will be incorporated into the concrete mix, which would increase the water-cement ratio of the surface concrete and weaken it, ruining all our curing efforts. You won't have time to run out and buy an extra bag of concrete, so make sure you have enough before you start pouring, as well as all the necessary tools (shovels, concrete rakes, screed boards, floats, trowels, a broom, an edger and a grooving machine). There are always small bubbles of moisture in concrete, so even after achieving what is commonly considered “total strength”, the concrete will still harden a little.
If there is not enough water, the crystals cannot grow and the concrete does not develop the strength it should. Therefore, the goal is to keep our young and impressionable concrete moist and at the right temperature (ideally between 50 and 85 F). This drying process, known as hydration, begins the moment the water is mixed with the dry concrete mix, giving you a limited time to get wet concrete into the forms before it hardens. I like it when you have pointed out that the reason why concrete is slow to dry is because the water trapped in it needs to completely evaporate first.
By the time a week has passed, the concrete will have reached approximately 90 percent of its final strength and it is generally safe to drive on it.