Modeling of Creep Properties of concrete at Early Ages

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In this study, the following experiment and numerical analysis were conducted to investigate the creep property of concrete at early ages and to examine the basic factors necessary for its modeling.1. Concrete is considered as a composite material made up of mortar and coarse aggregates. Then, mortar is the part which deforms due to creep. Therefore, uniaxial creep tests in compression were conducted for mortar specimens at early ages. The drying creep strain and the basic creep strain were measured in those tests. The age at loading was less than 24 hours. Choosing age of mortar, ratio of stress to strength, and water-cement ratio as the influencing factors, their influence on creep strain of mortar was estimated from the test results. In the test, surrounding temperature and humidity were kept constant (20ﾟC, 70% RH) in a computer-controlled chamber.2. The method of modeling to deal with the large statistical scatter involved in the creep of concrete was investigated. The effectivene … More ss of the concept of a probabilistic model to the modeling of the mechanical property with a large statistical variation was confirmed through numerical simulations using a practical design formula as a part of the constitutive model.3. A kind of complex element called concrete element based on the finite element method was developed to investigate the influence of the size and the spatial distribution of coarse aggregates on the creep and shrinkage of concrete. in this case, concrete is modeled as a composite material made up of mortar and coarse aggregates in the structural level of coarse aggregates. The effectiveness of the concept of a concrete element to the numerical analysis of such an internal structure of concrete was confirmed through various numerical simulations on the deformational behavior of concrete.The creep test for concrete specimens based on this basic study and the investigation of the creep of concrete of actual structures may be considered as the extension of the present study. Less