Image: Monolithic slab and stem walls for a shed, being hydrated for several days by frequent watering. By Impact Construction Sudbury Ltd.
When it comes to concrete construction, one of the most important steps after pouring is curing. Proper curing ensures that the concrete achieves its maximum strength and durability. One common practice that significantly aids the curing process is watering the concrete. But how exactly does watering help, and why is it important? In this blog post, we'll explore the effects of watering concrete during curing and the benefits it offers.
Understanding the Concrete Curing Process
Concrete curing is the process of maintaining adequate moisture, temperature, and time to allow the concrete to achieve its designed properties. When concrete is poured, a chemical reaction called hydration begins between the cement and water in the mix. Hydration is critical because it forms the binding matrix that gives concrete its strength. However, for this reaction to continue effectively, the concrete must retain moisture for an extended period.
Why Watering Concrete is Important
Prevents Cracking
Concrete that dries out too quickly can develop cracks. When the surface of the concrete loses moisture too fast, it can shrink, causing cracks that weaken the overall structure. Watering the surface helps maintain the necessary moisture levels, reducing the risk of surface cracking.
Ensures Proper Hydration
Water is essential for the hydration process to continue after the initial setting of the concrete. If the concrete dries prematurely, the hydration process halts, leading to reduced strength and durability. By keeping the concrete moist, hydration continues, allowing the concrete to gain the strength it was designed for.
Improves Durability
Concrete that has been properly watered and cured is more resistant to environmental stresses like freeze-thaw cycles, abrasion, and chemical exposure. This added durability is especially important for outdoor projects, such as sidewalks, driveways, and bridges, where concrete is subjected to harsh conditions.
Maximizes Strength
Concrete gains strength over time, but this process is heavily dependent on maintaining adequate moisture. The standard 28-day curing period is critical for the concrete to reach its maximum strength. Watering the concrete during this time ensures that the strength development is not compromised. Without proper moisture, the concrete may not reach its full potential, leading to weaker structures that are more prone to wear and damage over time.
Best Practices for Watering Concrete During Curing
Start Immediately
Once the new concrete has been finished and feel hard to the touch, begin the curing process as soon as possible. On hot days concrete can dry out rapidly - you want to avoid this.
Use Consistent Methods
One of the most common methods for watering is through misting or spraying the surface. This ensures even moisture distribution without washing away the surface. Another method is to cover the concrete with wet burlap or a plastic sheet to trap moisture.
Monitor the Weather
Weather conditions play a big role in how you should water concrete. In hot, dry, or windy conditions, the surface can dry out rapidly, requiring more frequent watering. Conversely, in cooler, damp conditions, less watering may be necessary, but the process should still be consistent to avoid uneven curing.
Duration of Watering
The ideal curing period is typically 7 to 14 days, with 28 days being the gold standard for optimal strength. During the early stages, particularly the first few days, it is crucial to maintain moisture by watering frequently. The longer the curing process is sustained, the better the end result.
Ponding
Ponding is one of the most effective way to cure concrete slabs. It is accomplished by using sand or clay around the perimeter of the slab to form a dam, holding water on top of the slab. For houses with basements, the stem walls act as a barrier to keep water in. With the right amount of water, it will take 2 - 3 weeks to get absorbed and/or evaporate, just the right amount of time for the concrete to reach it's max strength potential.
Consequences of Inadequate Curing
I see it so often that I decided to write a blog post about it. Concrete getting poured and then left unattended, to bake in the hot sun, leaving the owners with weak concrete, because they were never instructed to maintain the curing process after the pour. Failing to water concrete during the curing process can have long-lasting effects which can lead to expensive consequences. Concrete that isn’t properly cured will suffer from:
Reduced strength: The concrete won’t reach its designed compressive strength.
Higher permeability: This makes the concrete more vulnerable to water penetration, leading to issues like freeze-thaw damage or corrosion of reinforcement.
Surface defects & cracking: Without sufficient moisture, surface cracks, dusting, and scaling are more likely to occur, reducing the aesthetic and structural quality of the concrete.
Conclusion
Watering concrete is so simple and may even seem odd or unnecessary to some. However, keeping concrete wet is the most critical part of the curing process. By ensuring that your concrete retains the moisture it needs to properly hydrate, you are protecting the integrity of your project. Whether it's a patio, walkway, driveway, foundation, slab, or even smaller projects like edgings and curbs, properly cured concrete will last much longer, resist damage, have less cracks/shrinkage and achieve its full strength potential.
In the construction industry, especially at Impact Construction Sudbury Ltd, we emphasize the importance of proper curing techniques, including watering, to ensure the longevity and quality of our concrete projects. Whether you're a professional contractor or a DIY enthusiast, remember that how you cure concrete can literally make or break your concrete job.
By maintaining the right curing environment, you're not just following "proper procedure" – you're building something that will stand the test of time. And that - is priceless.
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