|Shrinkage of concrete made with limestone-rich cements
The application of grounded limestone as a main component of clinker reduced cements and concretes enables a significant reduction of construction related environmental impacts, especially CO2 emissions. A great concern regarding to shrinkage behavior of such concretes will be the variation of chemical and mineralogical composition of the available limestone. Thus, the questions regarding to the shrinkage behavior of cements and concrete with very high limestone contents should be answered.
Within the current research project, the shrinkage mechanisms (autogenous shrinkage and drying shrinkage) of water reduced concretes made of limestone-rich cements will be studied fundamentally to reach a precise prediction of shrinkage deformation of construction elements made of such concretes. The shrinkage behavior will be firstly methodically investigated on hardened cement pastes with different combination of Portland cement clinker and limestone. Furthermore, the influence of quality of limestone (chemical and mineralogical composition), degree of hydration, curing duration, w/c-ratio as well as relative humidity of surrounding environment will be analyzed. In further test series, the shrinkage deformation will be determined directly on the concrete samples. In these tests the influence of cement composition, ITZ, geometry of specimens and moisture transport and the paste content will be assessed.
Based on the performed experiments it is planned to develop a new model or modify the existing prediction models for shrinkage deformation of hardened cement paste and concretes made of limestone-rich cements. Finally, concepts for shrinkage deformation of concretes composed of limestone-rich cements to be used in design and application of structural elements under practical boundary conditions will be presented.