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How to Cure a Concrete Block & Mortar

By Sarah Morse ; Updated September 21, 2017

Curing, done properly, ensures that your concrete and mortar grow as strong as possible. It occurs in two steps. First is the original hardening process, which is quick. Second, the concrete and mortar compounds grow crystals, which strengthens them. In order for the crystals to grow, they need moisture for a prolonged amount of time. A curing compound prevents evaporation and allows the cement or mortar to cure. Knowing how to apply this and cure your concrete helps it reach its full potential and prevents the cracks that form without curing.

Pour the concrete, and apply the mortar on a day without strong winds, if outdoors. The temperature of the air and concrete should be above 40 degrees Fahrenheit and below 80 degrees Fahrenheit for at least a week after pouring. Higher temperatures call for a quicker application of the curing compound to prevent water loss. Lower temperatures cause the water to freeze and expand, creating cracks in the new concrete.

Apply a curing compound to the concrete and mortar with a hand sprayer immediately after the surface water disappears. This seals the water in and allows the crystals to grow. Apply a thick coat, leaving no area of the concrete exposed to the air. Any voids allow water to evaporate.

Apply a breathable sealant to the concrete after the curing compound is dry, especially if you live in areas prone to freezing temperatures. When purchasing, make sure the label indicates it's a breathable sealant. This fills in the spaces in the concrete, preventing water from filling these spaces, freezing and cracking the concrete. Apply the sealant with a paint roller.


Things You Will Need

  • Curing compound
  • Hand sprayer
  • Breathable sealant
  • Paint roller

About the Author


Sarah Morse has been a writer since 2009, covering environmental topics, gardening and technology. She holds a bachelor's degree in English language and literature, a master's degree in English and a master's degree in information science.