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Curing of High-Performance Concrete: Phase 1 Study.


pdf icon Curing of High-Performance Concrete: Phase 1 Study. (615 K)
Carino, N. J.; Meeks, K. W.

NISTIR 6505; 39 p. April 2001.

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Keywords:

concretes; curing; high performance concrete; mortar; statistical analysis; tensile strength

Abstract:

This report summarizes the results of an exploratory study on the effects of curing duration on the variation of mortar strength with distance from the drying surface. A novel, notched cylindrical test specimen was adopted for measuring tensile strength at different depths. Two mortar mixtures with w/c of 0.30 and 0.45 were used; the former was assumed to be representative of the paste system in a high-performance concrete. Specimens were moist cured for (1, 3, or 7) d and then exposed to air at 25 deg C and 50% or 70% RH. The cylinders were sealed to simulate one-dimensional drying in a large member. Tensile strengths were measured at 28 d. Relationships between tensile strength and depth were compared with those of specimens continuously moist cured. The data tended to show that 1 d of moist curing might be sufficient to ensure adequate strength development at a depth of 25 mm from the exposed surface. The phenomenon of increasing strength with drying may have confounded the results, and recommendations for additional studies are provided.