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Curing
How to Cure Concrete
Curing is often the most neglected practice when placing concrete. Improper or failing to cure your concrete will have a significant impact on look and quality of the finished product. Uncured concrete is likely to develop a pattern of fine cracks (called crazing) and once it's in use the surface will have low strength that can result in a dusting surface that has little resistance to abrasion.
Curing does more than just keep concrete from crazing, keeping in moisture gives concrete the time it needs to gain strength properly. Concrete strength depends on the hydration of the cement. If there isn't enough water, the concrete doesn't develop the strength it should and can result in structural cracking below the surface.
Properly curing concrete improves strength, durability, and wear resistance.
How to cure concrete:
There are two methods to cure concrete-
1. Add water to the surface to replace the water that is evaporating.
2. Cover the concrete to prevent the water from evaporating in the first place
Note: Adding water to the surface is NOT the same as adding water that will be worked into the concrete mix--that would increase the water-cement ratio of the surface concrete and weaken it, ruining all your curing efforts.
Types of Cures:
• Water cure:
The concrete is flooded or fogged. This is a very effective curing method for preventing mix water evaporation. The effectiveness of this method is highly dependent on the temperature and wind. This work best when it’s above freezing and humidity is low.
• Coverings:
Use coverings such as burlap that is kept continuously wet or by using plastic sheeting to keep moisture in. These are easily applied but may not be suitable for large projects. Burlap has to be continuously sprayed and plastic sheeting can prohibit adding extra water. Coverings can cause discoloration and leave wrinkle marks.
• Chemical Membranes:
This needs to be done as soon as the concrete is finished. Chemical cures are sprayed on the fresh concrete, usually one coat per 150-200 sq ft per gallon. Chemical cures can affect the bond of pliable flooring making it difficult to apply tile or anything requiring an adhesive. Make sure you let your supplier know what covering you are using so you get the right cure.
Color and your Concrete:
The best approach for decorative concrete is to try to alter conditions so you don't need to do initial curing: block the wind, keep the sun off the concrete, or get cooler concrete. If that's not possible, fogging just enough to keep the surface damp is possible, but the simplest approach is to use a chemical membrane. This chemical can be sprayed on to form a thin membrane on the surface that prevents the water from evaporating. It completely dissipates after 3 days just in time to seal. Click here to view color concrete cures and sealers.
How_to_cure_concrete.pdf
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