Whether you’re pouring a slab for a shed, installing concrete stairs, or setting footings for fenceposts, one of the most common questions that pop up is “how long does Sakrete take to dry?”
Sakrete is one of the most commonly used premixed concrete brands, so it gets used for all sorts of projects around the house.
Like other concrete, though, it only remains soft and workable for a certain amount of time before hardening. That means you’ll need to plan out your project while keeping in mind that you have a limited time to mix and pour the concrete mix.
Concrete Drying Explained
Concrete is a composite mixture of three ingredients: cement, sand or rock, and water. When water is added to the dry mix, the cement begins a chemical reaction and turns into a semi-liquid sludge.
At this point, the clock has started on the concrete drying, which means you’ll need to do all your mixing, pouring, and shaping before it gets too dry.
Different concrete products have different drying and curing times, depending on the intended use of the concrete mix.
Sakrete High-Strength Concrete Mix will dry enough to handle foot traffic in 24 hours, and vehicle traffic in 72 hours. Sakrete Fast-Setting Mix will dry in 30 minutes and is ready for foot traffic in 6 hours, and vehicle traffic in 48 hours.
This represents a major difference in drying times between the fast-setting mix and the high-strength mix. Whether or not the faster dry times are worth the added cost of a fast-setting mix will depend on the specifics of the project, and how quickly you need to get the job done.
Drying Time Variables
In addition to the specific concrete mix, there are a number of other factors that influence how long Sakrete takes to dry.
Temperature is a major factor when you’re talking about concrete drying and curing times. The hotter it gets, the faster the concrete will dry and cure, and in sweltering temperatures, this can have a negative impact on the final product.
Generally, you want to mix and pour concrete when it’s less than 80° F. Hotter than that and you’ll run into problems with water evaporating from the mixture too quickly, which leads to spalling and cracking on the surface.
There are several ways to mitigate this issue. You can use cold water when mixing your concrete, you can mist the surface with water both before and after you pour the concrete, and you can apply your concrete in the early morning or evening when the heat is less intense.Cold weather can also have a major impact on concrete drying and curing. Colder weather slows down the chemical reaction significantly, which means it will take longer for the concrete to set and fully cure.
Concrete should be kept above 40°F, and ideally 50°F, while it’s drying and curing in order for it to cure correctly. Any colder than that and you’ll run into issues with weakened concrete from it curing too slowly.
There are a number of steps you can take to keep your concrete warm even when the temperatures dip below the ideal range. Insulated concrete blankets, heating coils, or even burlap cloth can help trap heat inside the slab and maintain the proper temperature.
Moisture is another issue when you’re dealing with concrete drying and curing times. Too much moisture in the concrete mix and you’ll end up with excess water retained in the concrete even after drying.
This leads to small cracks forming as the trapped water eventually evaporates, as well as lower compressive strength over time.
The best thing you can do to prevent excess moisture follows the manufacturer’s instructions.
Sakrete’s High-Strength Mix recommends 2.5 qt (2.4 L) of water per 60 lb bag of dry concrete. Their Fast-Setting Concrete Mix recommends 2.5 to 3 qts (2.4 – 2.9 L) for each 50 lb bag of concrete.
Another thing to pay attention to is moisture transfer from the surrounding environment.
Pouring wet concrete onto hot dry sand can lead to the mix drying out too quickly. Alternatively, if you pour concrete in a wet humid environment, then you’ll want to take steps to prevent too much moisture from absorbing into the mix.
Some steps you can take to avoid these issues is by using concrete form liners or vapor barriers.
How Long Does Sakrete Take to Cure?
While they might sound similar, drying and curing are not the same when it comes to concrete.
Drying refers to concrete transforming from a sludge-like paste into a solid. When it dries it’s set enough to handle light foot traffic, but it’s still a long way from achieving its final strength.
Curing refers to the process of maintaining the ideal moisture, temperature, and time for the concrete to achieve its final strength. While drying can take as little as a couple of hours, it typically takes 30 days until the concrete is completely cured.
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