Influence of aggregate grain size distribution and superplasticizer type on fresh concrete rheology

This thesis presents the investigation of the rheological properties of fresh self-compacting concrete\ud and heat development due to binder hydration. Heat of hydration was also correlated with the increase\ud of compressive strength in concrete. Rheological investigations were performed using a ConTec\ud Viscometer 5 coaxial rheometer and a standard and modified slump-flow test method. The purpose of\ud the investigation was to determine the influence of the aggregate grain size distribution, water-cement\ud ratio and the amount and type of superplasticizer on the properties of fresh self-compacting concrete\ud mixtures. We strived to obtain a concrete mixture with the best self-compacting properties in fresh\ud state by varying the input components according to a predetermined rule (parametric study). In the\ud framework of the study two different types of superplasticizers were used – the polycarboxylate ether\ud based and the polyphosphonate based superplasticizer. A comparison of their effects on the properties\ud of fresh concrete and its hydration and hardening process was made. Using a C3 Analysentechnique\ud MC - Cal/100 isothermal calorimeter the hydration heat flux and the total amount of released\ud hydration heat were observed. The obtained results are shown in relation to the results of compressive\ud strength tests of concrete at a certain age