ASSESSMENT OF RISK OF THERMAL-CRACKING IN HARDENING CONCRETE

At the Lulea University of Technology, research has been performed on thermal stresses and thermal cracking in maturing concrete in the last decade. Laboratory tests have been carried out providing material dat a for calibration of a proposed theoretical model for thermal stress a nalysis in young concrete. The laboratory tests included creep tests, free thermal volume change tests and relaxation tests. In the theoreti cal model, the thermal properties and the transient mechanical propert ies of the young maturing concrete as well as the restraint within the concrete element are considered. The model has been implemented in a computer program permitting the analysis of different concreting scena rios of which some examples are shown. In the examples, influences of different measures against cracking as well as influences of changes i n temperature conditions, restraint, and mechanical behavior of concre te are quantified. For some cases in the computational studies it may be concluded that, for control of early-age thermal stresses and crack ing in a structure, it is highly inadequate to consider only the early -age distribution of the temperature field within the studied structur es.