AUTHORS: Michal Kropacek, Radim Cajka
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ABSTRACT: The paper describes experimental measurement of volume changes of cement concrete. Shrinkage is now becoming increasingly important with respect to concrete construction requirements, and it is important to be able to accurately measure and evaluate volume changes. Volume changes include swelling and shrinkage of cement concrete specimens. The experiment includes evaluating effects on volume changes and, depending on the environment, also evaluating individual types of volume changes in concrete such as drying shrinkage and thermal expansion. Volume changes was measured by string strain gauges both internal and external (with experimental casting method). The specimens were in the laboratory and in the outdoor environment, so it was possible to compare values from different environments. Within the experiment, the measurement methodology of string strain gauges was unified for future experiments, which was one of the experiment goals. The measured results are compared with the calculation models of shrinkage: Model B4 [5], CSN EN 1992-1-1 [8], ACI 209.2R-08 [11] and Model Code 2010 [14]. Comparison of shrinkage results with calculation models is important in designing concrete structures and developing other parameters for calculation models. The results from the experiment will serve to further investigate the volume changes depending on the subsoil. The concrete used in the experiment served as comparative, and the measured values would serve as a benchmark for dispersed reinforcement (steel fibers) concrete proposed in future experiments. Concretes with dispersed reinforcement using steel fibers has a positive effect on the reduction of volume changes and measurement of these concretes will be the next step of the research with the emphasis on building practice, especially industrial floors.
KEYWORDS: Concrete, Volume Changes, Shrinkage, Swelling, Calculation models, Cement
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