Technical Questions

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The effect of air content on concrete strength

Q. How does air content affect strength?


A. Intentionally entrained air voids improve the resistance of concrete to damage from cycles of freezing and thawing. Any air voids reduce the strength of concrete, with about a 5% reduction in strength for each 1% increase in the volume of air voids. Air voids, however, also improve the workability of concrete. Therefore, air-entrained concrete at a lower w/cm can be prepared to provide similar workability to non-airentrained concrete, thus compensating to some extent for the reduction in strength.


References:  SP-1(02); E4-12; ACI 212.3R-16

Topics in Concrete: Admixture; Concrete Fundamentals; Quality AssuranceTesting of Concrete

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