So, your Buffalo NY concrete project is almost completed! You’ve planned it, prepared it, formed it, poured and finished it. As you complete the final pass with your trowel, you’re already imagining how it is going to look when it’s dried. All that’s left to do is clean your tools, grab a beer, and enjoy the fruits of your labor, right? Not necessarily. Whether it’s a small patching job, installing a new driveway, or building a highway; a few additional steps and precautions after finishing you can ensure your next concrete project will reach its full potential.
In the world of concrete, the maintenance of the drying and setting process is referred to as curing. The purpose of curing is to keep adequate moisture content and temperature as soon as the concrete is placed and finished. It is one of the most important (and overlooked) steps and can have the greatest effect on the final outcome. Properly cured concrete can have significantly superior properties compared to concrete left to set after finishing. Sufficiently cured concrete will exhibit greater durability, wear resistance, and gain strength faster. Cured concrete will also have better resistance to deicers and freeze/thaw damage. Improperly cured concrete can be subject to plastic shrinkage cracking (loss of moisture from fresh concrete) and drying shrinkage (loss of moisture from concrete that has set) among other undesired side effects.
Concrete sets and reacts with water in a chemical process called hydration. The components of cement in concrete react with the water and this causes the cement to congeal and harden. Hydration won’t occur under every condition, however. If the internal humidity of the concrete falls below 80% or the temperature is below 14 degrees Fahrenheit, hydration will stop completely. The hydration process also produces heat, and it is important to maintain less than 35 degrees temperature difference between the exterior and core.
Curing methods, simply put, involve protecting the exposed surfaces of any concrete mass from excessive evaporation or temperatures and maintaining an adequate supply of water for the hydration process to take place. Though concrete will continually cure and hydrate throughout its life, the process is most active in the first 7 days after placement. That is why during this critical time it needs to be protected. There are 3 methods you can employ after laying concrete to properly cure it. One method is to seal in the water already present in the concrete from mixing. This can be done by spraying a curing compound after it is finished which will create a membrane on the surface that reduces evaporation. Covering your concrete with waterproof paper or polyethylene sheeting will also have a similar curing effect. The second method involves supplying additional water to the concrete as it hydrates. This can be achieved by ponding or immersion of the concrete, spraying or fogging the surface of the concrete throughout the curing period. Saturated wet coverings, such as a moist sand or wet burlap covering can also be used. This method of curing also cools through evaporation which can have some advantages during hot weather placing. The final method is the most involved and complicated. To supply heat and additional moisture electrically heated pads and forms (mostly used in precast concrete), heating coils, and even live steam is used.
The method you choose for curing concrete will vary according to conditions, resources, and availability of materials. Larger projects should have their own curing plan in place before placing begins. Hot and cold weather placement should also have special considerations and precautions in place.
By taking the time to properly cure your next construction project, whether it’s a large concrete slab or driveway to a small DIY concrete mix, you can ensure that your investment will continue to pay off throughout its service life. Though it involves a few extra steps and will prolong the time from placement to use, the long-term benefits far outweigh the relatively small amount of time it takes to properly cure your concrete.