Concrete Curing Dos and Don’ts
You may properly regard concrete as one of the most durable and visually appealing building materials available, but did you realize that everything you do after pouring has just as big of an influence on its strength as the mixing process? In reality, the chemical process that binds sand and gravel together to create concrete takes roughly 28 days to complete. You want to preserve moisture in the concrete during this process, known as hydration. Otherwise, water evaporating too fast from the surface, which is easy to accomplish outside and in direct sunlight, can damage the completed product with strains and cracks.
Controlling the moisture content and temperature of the fresh concrete for the first few days during curing is of the utmost importance. By paying close attention to the concrete mix throughout this time rather than walking away as soon as it’s poured, you may improve the structural integrity of the concrete and make it more resistant to future breaking. Check out our list of the best (and worst) concrete-curing procedures before starting your next job for the greatest outcomes.
DO water-spray fresh concrete.
For the first seven days, one of the most typical techniques for curing concrete is to spray it off often with water—five to ten times each day, or as often as you can. This is known as “wet curing,” because it enables the moisture in the concrete to gently escape. Moist-cured concrete has been shown to be up to 50% stronger than dry-cured concrete! Spraying is not suggested for cold-weather concrete pours; for cold-weather pours, see “Don’t Let Concrete Get Too Cold,” below.
Cover any fresh concrete.
When you don’t have time to return to your concrete as many times as required for full moist curing, another alternative is to use a cover that may retain and limit the evaporation of the moisture in the mix. Polyethylene sheeting at least 4mm thick or a concrete curing insulating blanket (both available at DIY shops) are suitable for this work. Wet the concrete well, then cover it with the sheeting of your choosing, securing it with bricks, boulders, or other heavy materials. Remove the sheeting or blanket on a daily basis, re-wet the concrete, and re-cover it for seven days. This method may also be used to damp down and cover upright concrete columns and walls with a curing blanket or plastic sheeting.
Pond cure concrete slabs YES.
Pond curing is another excellent method for curing concrete, and the procedure is just as it sounds: You build temporary berms around a fresh concrete slab before flooding the space within with one foot of water. Three days of pond curing is equivalent to seven days of wet curing, and it requires no daily attention—just keep the water level above the concrete slab. If it falls, you’ll need to refill it slightly. This approach, however, is not for everyone since it requires a significant amount of dirt to construct berms around a large concrete slab. Large-scale builders may employ this strategy to expedite the building process, such as when laying foundation slabs and moving on to frame the structure.
Apply a curing substance to make the procedure simpler.
If none of the other ways are practicable, there is a simpler solution: cure chemicals. These soluble emulsions, available from DIY shops and ready-mix concrete firms, generate a protective coating when sprayed directly onto the surface of freshly poured concrete slabs or walls. Finally, the film acts as a barrier to keep water from evaporating, enabling it to cure at a steady pace. Some curing ingredients are meant to dissolve entirely after a few weeks, while others should be scrubbed away when the curing process is over. Others, such as Quikrete Acrylic Concrete Cure & Seal, penetrate the surface of the concrete to form a permanent sealant that waterproofs it and keeps it appearing newly poured. Before selecting a curing compound, carefully read the manufacturer’s label to verify that it suits your unique requirements.
DO NOT FORGET to replace control joints in concrete slabs.
The objective of any concrete installation is to generate a high-quality, crack-resistant product. While curing concrete helps to reinforce the completed structure, many concrete slabs will fracture regardless of measures owing to concrete shrinkage as water is used up in the hydration process as well as temperature changes. Do-it-yourselfers can place control joints at predetermined locations to guide the inevitable cracks to preserve the beauty of the slab in the face of these challenges. These seams should be cut in a fourth of the depth of the concrete slab at the start of the curing process, no later than 24 hours after the original pour. The control joints may be readily and smoothly cut into the concrete surface at the required distances in the slab using a metal jointing tool.
Multiply the intended concrete thickness (in inches) by 2.5 to get the maximum distance between joints (in feet). For example, if you’re laying a 4-inch-deep sidewalk, multiply 4 by 2.5 to achieve a spacing of 10 feet between joints. Place them closer together for further crack prevention. On a bigger square slab, such as a patio, try fracturing the concrete with perpendicular joints—both down and across. Then, if your slab patio, driveway, or sidewalk breaks, it will very certainly do so along a precut joint and will therefore go undiscovered.
DON’T LET NEW CONCRETE COOL DOWN.
The optimal time to pour concrete is when temperatures are projected to stay above 50 degrees for five to seven days, but preparations might go haywire if an unexpected cold front arrives. If you want to know how to prevent concrete scaling this occurs, the emphasis moves from keeping the concrete moist to keeping it heated enough to prevent the chemical hardening process from being disrupted. Concrete’s chemical reaction slows at 50 degrees Fahrenheit and stops altogether at 45 degrees Fahrenheit, indicating that it will lay dormant and lose strength. You cannot pour concrete and utilize it within a few of days. When the weather turns cold, cover fresh concrete with concrete insulating blankets (or, in a pinch, old household blankets!). Protect fresh concrete from the cold for the first two to three days—up to a week if it’s really cold—after which it should be robust enough to handle without harm.
During the first month, DO NOT PAINT OR STAIN THE CONCRETE.
Any paint or stain applied to young concrete while it is still hardening can be harmed by residual moisture or changing chemical content. The hydration mechanism consumes all of the water within roughly a month. Brushing on paint too quickly, while moisture is still rising to the top, may apply pressure behind the paint’s hard barrier, causing it to peel away or break the bond. As a result, paint may not adhere as well, and the final color and appearance of stained concrete may suffer as a result. To get the best results, wait until the 28-day period is finished before applying paint or stain, and then follow the top advice suggested in this video from Quikrete’s concrete experts.
DO NOT SUBMIT NEW CONCRETE TO EXTREME WEIGHT.
Although concrete hardens quickly after pouring, it is nevertheless vulnerable to weight damage over the first four weeks. Allow at least 24 hours before permitting foot activity, including dogs, on a freshly poured sidewalk or slab, and wait at least 10 days before driving a car on a new driveway. After that, conventional passenger vehicles may drive on the concrete; big trucks or RVs can roll into the driveway after the concrete has reached its maximum strength, which should be approximately 28 days.