Technical Questions

ACI Committees, Membership, and Staff have answered common questions on a variety of concrete related topics.



What is the effect of freezing on concrete?

Q. What is the effect of freezing on concrete?

 

A. Freezing of freshly mixed concrete can be very harmful. It can disrupt the mass and permanently impair the strength and effectiveness of the air-void system. To prevent damage from freezing at early ages, concrete should be protected from a single freezing cycle until a compressive strength of 3.5 MPa (500 psi) is developed. If exposed to cycles of freezing and thawing while critically saturated, concrete should be protected until its compressive strength has reached 24 MPa (3500 psi).

When protecting concrete beyond the first day, it is particularly important to keep the concrete from drying. Because of its low absolute humidity, winter air has a great affinity for water when its temperature is raised, so that unprotected concrete dries rapidly in heated enclosures.

 

References: SP-1(02); ACI 306R-16; ACI 306.1-90

Topics in Concrete: Cold Weather; Concrete Fundamentals; Placing

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