What is curing?

External curing involves maintaining the moisture and temperature of newly placed concrete to ensure that the specified strength and durability is achieved for your job. In some instances, internal curing may be used with added elements to assist in the curing process, but all newly placed concrete must be allowed to externally cure for a minimum of 3 days, ideally at least 7.

Why cure concrete?

• Improved durability – properly curing concrete results in less cracking, more resistance to wear and abrasion, and a more watertight surface, which reduces the intrusion of water-borne chemicals

• Better appearance – proper curing significantly reduces the potential for surface issues, such as crazing, dusting, and scaling, and results in a cleaner finished look for your job

• Predictable strength gain – if concrete is not allowed a proper cure, the strength and durability of the concrete may be compromised, and the end result may not meet specifications.

In short a proper cure allows for not just a great looking job, but a safe, strong, and durable concrete to meet your needs.

How to cure concrete:

• Maintain moisture – there are many different methods of applying water to the surface of the concrete during curing, but perhaps one of the most common is the use of absorbent materials, such as burlap or cotton mats, that are weighted down to maintain contact with the concrete. Alternatively, plastic sheets, waterproof paper, and liquid membrane-forming compounds may be applied to retain water in lieu of methods that require a water source.

• Control temperature – concrete should not be allowed to cool faster than 5º per hour for the first 24 hours to ensure proper strength gain and final strength. Water retention methods should always be used if freezing temperatures are expected, and water curing can aid in lower curing temps in hot weather.

• Termination of curing – always follow the specifications provided for concrete curing. Generally, at least 3 to 7 days is required to achieve the strength and durability rating of the product. Any cover materials should be dry before removing, and follow proper controlled drying procedures if using a wet curing method.

Adapted from IRMCA – CIP 100

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