Concrete Curing Dos and Don’ts for Achieving Maximum Strength

W.R. Meadows

Many concrete contractors will tell you that the most critical aspect of any concrete construction project is proper curing. Even if you start with a good concrete mix, failing to cure a concrete slab adequately can have a significant impact on its strength, durability, and overall performance. Poorly cured concrete becomes more porous, making it susceptible to water penetration, chemical intrusion, and freeze-thaw damage. This increased permeability can lead to serious problems later, including corrosion of reinforcing steel, efflorescence, and surface defects like pitting, plastic shrinkage cracks, spalling, and discoloration. These defects not only affect the appearance of the concrete, but can also compromise its structural integrity.

Unfortunately, there’s no good fix for improper curing of concrete. You only have one chance to do it right, or else suffer the consequences later. By following these essential dos and don'ts, you can ensure that your new concrete slab will achieve the desired strength and durability.

CURING DOS

Do moist cure fresh concrete

Concrete sets and hardens as a result of a chemical reaction between cement and water, a process called hydration. To maintain optimal moisture conditions long enough for the concrete to fully hydrate, you should spray or mist the newly poured concrete with water frequently, as often as 10 times per day. This helps the concrete cure slowly and evenly. Moist curing is especially important during the first 7 to 10 days after concrete placement, which is when the concrete will increase in strength the most.

Do cover your slab

If you are unable to spray down your concrete several times a day, another option is to apply a covering to trap moisture and slow down evaporation. Options for coverings include polyethylene sheeting, burlap, and concrete curing blankets. To hold the covering down, place bricks, rocks or other heavy objects around the perimeter. For at least the first seven days after concrete placement, remove the covering daily and re-wet the concrete to maintain even moisture levels.

Do apply a curing compound

If wet curing methods aren’t feasible, another solution is to apply a membrane-forming curing compound, a spray-applied product that forms a thin, protective film on the concrete surface to reduce moisture loss and allow the concrete to cure at a consistent rate.

Some curing compounds are designed to disintegrate completely after a couple of weeks, while others penetrate the surface of the concrete and become a waterproofing sealer. These dual-function products, called “cure & seals”, are commonly used on decorative colored concrete because they help to protect and enhance the color. Learn more about cure & seal products.

Do consider pond curing

Also known as immersion curing, pond curing involves submerging concrete in clean water to maintain moisture levels during the curing process. It’s done by creating temporary berms or barriers around the concrete and then slowly filling the area with water until the entire surface is submerged. Pond curing is particularly effective for slabs placed in hot climates, helping to counteract rapid moisture loss due to high temperatures. But this method is not practical for all projects, since setting up the barriers and maintaining water levels can be labor-intensive and time-consuming.

1300-CLEAR - Curing Compound Wax based curing compound. Great for interior and exterior.

Cures & Cure & Seals Improved resistance to rain, the sun, freezing temperatures, stains, and more.

Water-based Curing Compound VOC-Compliant. Easily applied with spray equipment.

CURING DON'TS

Don’t allow premature drying

To ensure proper curing, concrete needs consistent moisture, especially during the first 7 to 10 days. If the concrete dries out too quickly, the surface of the concrete will shrink faster than the interior, leading to surface cracks and potential structural integrity issues. Protect the surface from direct sunlight and wind, which can cause rapid evaporation. If necessary, use barriers or coverings to shield the concrete.

Don't pour concrete in extreme weather

Ideally, concrete should cure at temperatures between 50° to 85° F. When concrete temperatures drop below 50° F, the hydration reaction slows and may even stop altogether. The opposite problem occurs when the concrete becomes too hot. This causes the cement to react too quickly, preventing the concrete from developing full strength. If you must pour concrete in cold weather, use insulated curing blankets (or even electric heating blankets) to keep the concrete warm (see Curing Concrete in Cold Weather). During hot weather, place the concrete early in the morning or later in the evening, when temperatures are cooler (see Curing Concrete in Hot Weather).

Don’t walk or drive on concrete too soon

The entire curing period for a concrete slab takes about 28 days, but the concrete will be ready for most foot and vehicle traffic sooner. However, you still need to wait for the concrete to develop enough strength to resist impact and weight without damage. Before allowing light foot traffic on a newly poured concrete slab, wait at least 24 hours. Wait at least 7 days before driving a car on a new concrete driveway, and even longer for heavier vehicles like RVs and large trucks (see How Long to Wait Before Driving on New Concrete).

Don’t paint or stain concrete while it’s curing

Because concrete contains residual moisture that needs to evaporate during the curing process, applying paint or stain too soon can trap moisture, leading to peeling, flaking, and blistering. To ensure proper adhesion, wait at least a month after concrete placement before applying a paint or stain. This allows the concrete to fully cure and moisture levels to stabilize.

FREQUENTLY ASKED QUESTIONS

How long does concrete need to cure?

It generally takes about 28 days for concrete to fully harden and attain its maximum strength. However, the most critical period for curing is the first 7 to 10 days, which is why your fresh concrete shouldn’t be allowed to dry out during this period.

Should you wet concrete while curing?

Yes! One of the most common methods for curing concrete is to spray it down with water as often as you can for the first week after placement. By maintaining optimal moisture levels, moist-cured concrete can be up to 50% stronger than concrete that hasn’t been kept damp during curing.

What is the best method for curing concrete?

No one method of curing works better or faster than another. Moist curing, pond curing, and the application of a curing compound are all good ways to maintain optimal moisture levels for proper curing. The choice often depends on specific project conditions, the climate, and practicality. Learn more: A Guide to Concrete Curing Time & Methods.

Can I cure concrete myself?

If you’re pouring a DIY concrete slab, curing is something you can easily do yourself, but consistency is key. For the best results, regularly check and maintain moisture levels to ensure that your newly placed concrete stays hydrated for the proper amount of time. Your vigilance will pay off in the long run, resulting in concrete that achieves its full strength potential.

NEED HELP WITH YOUR PROJECT?

• Find nearby concrete contractors that can make sure your concrete cures properly.
• Buy curing supplies: Concrete products available from trusted suppliers.