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In addition to these products, an air entraining agent may be used to maintain a required air content, and water reducing admixtures will control slump loss without affecting the water demand of the mix.

Other safeguards

In addition to using chemical admixtures, there are also physical procedures producers can use to combat the effects of hot temperatures. These preventive measures include cooling aggregates by sprinkling them with water or keeping them shaded from direct sun.

Contractors play an important part in preventing problems as well. They should wet the subgrade before the concrete is placed in an effort to prevent those materials from absorbing free water from the concrete mix.

Contractors can also erect wind barriers, use water misting, or apply evaporation retardants to protect the surface of freshly placed concrete from the rapid moisture loss that causes crazing and cracking.

Contractors should also begin curing procedures as soon as concrete is ready and continue this for at least three days.

There is lots of information published and supported by industry associations that promote good hot weather concreting practices. For more information, contact the following associations: the American Concrete Institute (www.concrete.org), the National Precast Concrete Association (www.precast.org), and the National Ready Mixed Concrete Association (www.nrmca.org).

SOURCE: AXIM ITALCEMENTI GROUP