Time-Dependent Compressive Strength Development in Florida Concrete (05-0706)**
Nur Yazdani, University of Texas, Arlington
Bryant McKinnie, No Organization
Saif Abdullah Haroon, SAIFUL/BOUQUET STRUCTURAL ENGINEERS, INC.

The Florida Department of Transportation (FDOT) specifications contain time dependent concrete compressive strength equations to predict equivalent 28-day strengths based on core strengths at other times. The FDOT models are many years old, and are not likely to represent current FDOT concrete mixes. Compressive strength testing using a typical FDOT concrete mix design at various ages was performed herein in order to develop appropriate strength variation models. Variation in the mixes was achieved through substitution of cement types, slag for fly ash, and coarse aggregate type. Selected existing models from the literature were examined for statistical goodness-of-fit to the test data. The best performing models relating the 28-day compressive strength to strengths at other time periods were recommended.