Slab Replacement Maturity Guidelines – University of Florida

Report on Slab Replacement Maturity Guidelines from University of Florida

This study investigated the use of maturity method to determine early age strength of concrete in slab
replacement application. Specific objectives were (1) to evaluate effects of various factors on the compressive
maturity-strength relationship of concrete at early age, (2) to develop appropriate test procedures for applying
maturity method to predict early age strength of concrete, and (3) to validate the accuracy of the prediction of
maturity method using the proposed test procedures.
The maturity method using the Arrhenius maturity function was found to be quite reliable and convenient for use
in predicting the early-age compressive strength of concrete in replacement slab application. Some limitations of
maturity-strength prediction, such as the strength loss due to high curing temperature and insufficient moisture,
supply were observed in the laboratory studies. However, these limitations were observed at the later age of the
concrete when the compressive strength reached around 3,000 to 3,500 psi, and thus the observed limitations did not
have any negative effect on the early-age-strength prediction of the concrete in the replacement slab.
Using the strength of the protection specimens as strength determination of the in-place concrete is unreliable and
may result in over-prediction of its strength. The maturity method using the Arrhenius maturity function is
recommended for use to estimate the early-age compressive strength of concrete in slab replacement application. A
testing protocol for the generation of maturity-strength curve for prediction of early-age compressive strength of
concrete was recommended. The concrete used in the replacement lab must have exactly the same water-cement
ratio, mix ingredients, and fresh concrete properties as those of the laboratory concrete used to develop the maturity
curve. In the event that differences in fresh concrete properties, with more than ±1 inch in slump and/or ±1 % in air
contents, are observed between the actual concrete used at the project site and the concrete which has been used to
develop the maturity-strength curve, the maturity-strength curve should not be used to make strength predictions
without proper adjustments of the predicted strengths due to effects of the variations in the fresh concrete properties.

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