This paper presents an investigation into the shrinkage of concrete treated with an evaporation reducer, Confilm®, after placement. Shrinkage tests were conducted on specimens treated with the evaporation reducer both properly and improperly. In the experimental program, concrete was cured under five curing regimens: 1) concrete was dry cured to serve as a basis for comparison, 2) concrete was cured with wet towels to simulate field curing with wet burlap, 3) the evaporation reducer was used as a curing aid to reduce early-age shrinkage in concrete by applying it to the surface before the start of the test and leaving it undisturbed throughout the test, 4) the evaporation reducer was used as a finishing aid during initial finishing (troweling), and 5) the evaporation reducer was again applied just after the concrete surface was floated, but was used as a finishing aid during final finishing (three and a half hours after water was added to the concrete). Dry curing produced the greatest early-age shrinkage. The reductions in shrinkage observed for wet curing and for the proper use of the evaporation reducer were similar. The effects of troweling the evaporation reducer produced early-age shrinkage that was approximately 75% greater than the shrinkage experienced by concrete properly treated with the evaporation reducer. However, the shrinkage of the concrete treated with Confilm® was still less than the shrinkage observed for concrete cured under wet towels. Consequently, it appears that there is little negative consequence to using Confilm® as a finishing aid. Initial finishing of the concrete treated with the evaporation reducer produced approximately 20% more early-age shrinkage than final finishing. To study the effects of the various curing regimens on tensile strength, four prism specimens were cast and cured along the sides of each shrinkage specimen. From modulus of rupture testing, no statistically significant differences were observed between the curing regimens.
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