engleski

Modeling of Temperature Changes and Mechanical Properties Distribution in Concrete

Knowledge of mechanical properties of concrete, i.e. its developement from a moment of concreting to the moment of taking load, is of great importance to designers and constructors because it can significantly contribute to the quick and safe construction. Relationships between the strength and modulus of elasticity are well known for the hardened concrete, where a process of hydration is mostly finished, and they can be considered as constant. However properties of concrete just after concreting and all the way until approximately 7 days of age, are unknown. In that early stage, concrete is transforming from liquid to a solid state and a hardening begins. Deformation of concrete due to shrinkage, and also ability of the concrete creep and relaxation are the greatest. At the same time, concrete is expanding due to the heating resulting from the release of the cement's hydratation heat. Also, because of a non-uniform temperature in the concrete element, the degree of hydration is also non-uniform as well as the mechanical properties of concrete. During construction of the Domovinski bridge in Zagreb, measurements of the temperature changes in concrete elements were performed. This paper gives the insight in conducted laboratory and field measurements as well as a comparison with computer modelling results of the temperature distribution prediction. Mechanical characteristics of concrete are determined by means of the maturity method.

maturity method; hydration heat; properties of concrete; temperature distribution; early age concrete

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