Curing Concrete and Protecting your Slab
Curing your concrete slab is one of the best ways you can preserve the integrity of the cement and reduce the likelihood of cracks. In other words, curing will have a major impact on your final product.
Uncured slabs of concrete will likely develop a pattern of fine cracks, and will not be strong enough to withstand years of weather and use. Curing concrete gives the concrete what it needs to maintain its strength and last for years.
Curing at the Right Temperature
Curing is somewhat of an art, however, as it cannot be done when the temperature of the concrete is either too hot or too cold. The ideal temperature range for curing is between 50 and 80 degrees – not air temperature, but concrete temperature.
Keeping Concrete Damp
The main goal when curing is to keep the cement damp and at the right temperature. First and foremost, you must keep exposed concrete surfaces moist while it is hydrating.
When the concrete is first laid, the bleed waters will rise as the concrete settles. During the period, if the bleed waters are evaporating from the surface of the cement faster than they are rising from the cement, then you’ll need to cure the surface or else end up with shrinkage cracks.
Determining the Rate of Evaporation
The rate at which the bleed waters evaporate depends on a combination of factors: the air temperature and humidity, the concrete temperature and the wind velocity. There are charts which may be used to help determine this.
Choosing your Curing Method
Once you have determined that you will need to cure your concrete, there are three different ways to go about it. You can add water to the surface to replace the water that is evaporating; you can seal the concrete to prevent the water from evaporating; or you can do a combination of both.
It is important to understand that any type of concrete, whether it is colored, stamped or stained, must be cured.
Wet curing is generally considered the most effective way to accomplish this process, and quality curing blankets can be ideal for colored concrete surfaces. The newer blankets intended for single-use are manufactured with an absorbent material combined with plastic sheeting, and these seem to work particularly well.
Wet curing also works best on slabs of concrete that will be acid stained. Many concrete contractors experience good results when they use a combination of both curing blankets and water.
It is best to use liquid curing compounds when curing colored concrete. A cure with sealer keeps the moisture in the concrete. It allows for a good cure on the concrete’s surface, and can then be applied as a sealer.
The bottom line is that curing concrete is an essential finish to a high-quality concrete job. If feasible, water curing remains the best method, and for colored concrete, a cure and seal is often your best bet. Just make sure you use a cure and seal material that complies with the requirements of ASTM C1315, Type 1, Class A.