If you’ve ever seen handprints, footprints, or pawprints on dried concrete, you’ve probably thought that people and pets walked on the material before it was fully ready. To keep that from happening to you on your next concrete project, here’s a guide to inform you how long it takes before you can walk on concrete.
Timeline for Drying Concrete
The proper drying time, also known as the curing process, is essential to know to protect your newly installed concrete. It’s important to remember that the longer the concrete sits, the stronger it becomes. Concrete can cure after only a few hours, but it doesn’t actually dry completely enough to reach its full strength. And the greater care you give to it, the longer it holds up and stays beautiful. Here’s the timeline to follow when curing concrete and how to treat it:
1. After a few hours
After the concrete is poured, it starts to cure immediately. It can be hard enough to support some weight after just a few hours. This is why you can see concrete workers standing on newly poured concrete just a few hours after pouring it. This allows them to finish the concrete and apply sealants or decorations.
But do keep in mind that even though it may appear dry, concrete is still wet under the surface at this point. You can still mar the concrete if you’re not careful, so it’s best not to walk on it at this point.
2. After 24-48 hours
Once the first full day passes after pouring the concrete, you can safely walk on it without damaging it. If it rained a lot on the area, or if you’ve done decorative stamping, then you should wait longer. Regular foot traffic should be fine at this point, but anyone must still be cautious about damaging the surface.
As much as possible, avoid any kind of dragging or twisting motion on the surface, like pulling out trash cans or moving planters across it. This will not damage the concrete, but it can create marks that aren’t easy to fix. Also, prohibit the use of skateboards, bikes, roller skates, and strollers on the day-old concrete – the smaller wheels concentrate weight on a small area, which can leave grooves in the concrete as they move.
3. After a week
After a week, you can safely allow most forms of traffic on the new concrete without worrying about marking the surface. It will be hard enough to drive on, but it’s best to avoid the edges and corners because they are still prone to breaking. Larger vehicles like semis and trucks should also wait longer. Avoid skidding and sharp objects as well.
4. After a month
Concrete takes about 28 days to cure and dry thoroughly. At this point, it has reached its maximum strength. If you’ve taken good care of concrete for a month, you can expect it to last for about 50 years before needing replacement.
Factors that Affect Concrete Drying Process
Many factors can affect concrete setting time, such as:
Water plays a big part in making concrete. Make sure to follow a ratio that the manufacturer recommends. If you add more water than necessary, you will get a runny mixture that will take longer to cure and dry. It must also not be too dry as it will be hard to mix.
Water is going to have to pass from the cement mixture into the surrounding air. The only way this is going to happen is if the air is drier than the concrete itself. If the air is humid, it will take longer for the water to pass from the concrete into the air, which will lengthen the drying time.
The temperature also impacts how long it takes the mixture to cure. Hot temperatures allow faster setting time because it promotes evaporation. Wind can also accelerate drying. If it’s cold outside, then it will take longer for concrete to cure than usual. The important thing is that the concrete mixture itself isn’t too hot or too cold. Cure it properly to achieve the desired strength.
Do’s and Don’ts When Curing Concrete
Curing concrete the right way requires some knowledge and finesse. The main thing to keep in mind that you must control the amount and rate of moisture that evaporates from the wet concrete material. Here are some do’s and don’ts to follow when curing fresh concrete:
Do moisture cure the concrete slab.
The first seven to ten days are the most important during the curing process, as it is when the concrete increases in its structural strength the most. Keeping it moist will help the curing process, and the hardening continues as long as moisture remains in the concrete. To keep the slab moist and prevent it from drying out, you can use misting, which involves spraying a fine mist of water at regular intervals across the surface of the slab. This will help maintain moisture to keep the surface damp at all times.
Do cover the concrete.
If you don’t have the liberty of time to mist your slab, you can cover it with a plastic sheet and wet it once a day. While covering the slabs, make sure that the plastic sheet extends beyond the edges of the slab by at least double the slab’s depth. Use heavy things like bricks and rocks to hold the sheet in place and prevent it from flapping in the wind. Remove the sheet every day and wet the concrete with water. Do this for at least seven days.
Don’t put excess weight on the new concrete.
Putting too much weight on the concrete before it’s ready can cause damage to your new concrete. To keep this from happening, avoid walking, driving, or putting heavy objects on top of it for the first week.
Don’t skip using control joints.
Control joints are essential for controlling the tensile stress that acts against the weakest parts of the material. Without them, the concrete will randomly crack. There are many ways to do this, but the most widely used way is putting control slabs at predetermined locations.