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by Chiara F. Ferraris
National Institute of Standards and Technology, Gaithersburg, MD
National Ready-Mixed Concrete Association (NRMCA), Silver Spring, MD
A survey and a literature review were conducted to identify the problems related with the production of high performance concrete (HPC). The main problems found are linked with workability and curing. HPC mixtures are often reported as being sticky and flowable. Concrete slump not being a good indicator of the workability, a new procedure that determines the fundamental parameters of rheology, is needed. Proper curing of HPC is of paramount importance to avoid cracking. Plastic shrinkage cracking can be avoided by preventing water evaporation from the surface before the concrete final set, but thermal cracking is less easily controlled and predicted.