ABSTRACT
Heat is always released whenever cement mixes with water. In the case of mass concretes, such heat may not be easily released and could lead to excessive temperature increase internally, depending on the prevailing temperature of the ambient environment, the amount of cement in the concrete mix and the size of the mass concrete. Numerical model using Crank Nicholson implicit finite difference method was developed based on 3D unsteady state heat conduction in mass concretes. Optimized MATLAB based software was developed for simulation and data visualization. A mass concrete block cast with standard mix ration and water cement ratio was used to verify the efficacy of the model. Type-K thermocouples and digital thermometer were used to monitor the temperatures at time intervals. The initial temperature just after placement was found to be uniform at all thermocouple locations. The temperature distribution afterwards exhibited a hotter core and cooler surface within the mass concrete block. The surface of block in contact with the ground recorded lower temperatures than the other surfaces for most of the time intervals. The highest temperatures for all thermocouple locations were recorded within 24 hours after concrete placement with the thermocouples located within the center (core) exhibiting higher temperatures and decreased towards the surface. After 96 hours of concrete placement, the temperature profile of the mass concrete block tends to revert to the prevailing ambient temperature. With the knowledge of the ambient temperature and the size of the mass concrete, the temperature distribution can be reliably predicted from which potential for thermal cracks occurrence can be determined to enable suitable proactive preventive cracks control measures.
