Freezing and Thawing Behavior of Internally Cured Concrete

The paper presents results from an experimental investigation on the freezing and thawing behavior of internally cured concrete. Air-entrained internally cured concrete was tested in a series of mixtures. The internally cured concrete was designed where a portion of the normal-weight fine aggregate was replaced with an equivalent volume of pre-wetted lightweight fine aggregate. The internally cured concrete was then exposed to cyclic freezing and thawing following the ASTM C666A procedure. This work was performed to determine whether properly designed, internally cured, air-entrained concrete may have an increased susceptibility to freeze–thaw damage. It is shown that when concrete is designed with a low water/cement ratio (w/c) (approximately 0.42 or lower) and a volume of internal curing water is added to match the chemical shrinkage volume, the internally cured concrete mixtures showed a very low potential for freeze–thaw damage (comparable to that of conventional concrete). The work did show that when water remains in the lightweight aggregates (because of a higher w/c that may not draw the water from the aggregate or when substantially more internal curing water is used than necessary), freeze–thaw damage may occur.