During its service life, concrete experiences volume changes. One of the types of deformation experienced by concrete is shrinkage. There are four main types of shrinkage associated with concrete: plastic, autogenous, carbonation, and drying shrinkage. The volume changes in concrete from shrinkage can lead to the cracking of the concrete. In the case of reinforced concrete, cracks in the cover concrete provide a direct path for chloride ions to reach and corrode the reinforcing steel. The development of concrete drying-shrinkage performance specifications with an associated test procedure was assessed for concrete mixtures purchased by the Virginia Department of Transportation (VDOT). Five existing shrinkage-prediction models were also assessed to determine the accuracy and precision of each model as it pertains to the VDOT mixtures used in this study. The five models are the ACI 209 Code model, CEB90 Code model, Bazant B3 model, Gardner-Lockman model, and Sakata model. The percentage length change limits for the portland cement concrete mixtures were found to be 0.0300% at 28 days and 0.0400% at 90 days. The CEB90 Code model was judged as the best prediction model for the VDOT portland cement concrete mixtures.
Samenvatting