Finite element analysis of temperature in hardening concrete using isothermal calorimetric data

University essay from Lunds universitet/Byggnadsmekanik; Lunds universitet/Institutionen för byggvetenskaper

Abstract: The produced heat in hardening concrete is of special importance to consider as the temperature rise within a large concrete structure can become such high that the structure may experience thermal cracking. With use of a simulation program that is based on the finite element method, the temperatures within the structure can be estimated to predict possible crack development. The heat produced by the cement is normally modelled with conventional methods that is based on semi-adiabatic measurements. However, recently isothermal calorimetry has been discussed as a method that measures the heat of the cement more accurate. The objective of this dissertation is to develop an algorithm to compute thermal power of hardening concrete using isothermal calorimetric data for finite element analysis. To examine how simulations with isothermal calorimetric data performs in comparison to the conventional method for thermal analysis of concrete, an experimental setup was built containing the same concrete as isothermal calorimetric data was attained for. The implementation of the algorithm was successful and now HACON is able to perform simulations with isothermal calorimetric data. The conclusion of the thermal analysis is that simulation with the isoconversional method and with the conventional method gives slightly different results. The experimental setup was also built successfully by Flemark, however, due to the complex air flow surrounding the setup, it wasn't possible to attain a definite conclusion whether finite element analysis based on heat calculations according to isoconversion is more accurate than the conventional method. The conclusion is that a program has been successfully developed but further work needs to be made to validate the accuracy.

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