RHEOLOGICAL PROPERTIES OF SCC IN TERMS OF ITS THIXOTRIOPIC BEHAVIOUR AND ITS INFLUENCE ON FORMWORK PRESSURE

Abstract

Thixotropic behaviour of SCC is not yet fully recognized. Understanding its nature and the factors influencing that effect, will enable to practical use of this phenomenon, especially in the processes related with casting of SCC. Previous studies showed, that SCC formwork pressure isn’t as high as the hydrostatic pressure. Knowing the factors influencing thixotropic behavior will allow to optimum use of the formwork, by its proper design, particularly in terms of technology. The paper present methods of measurements and results of rheological properties, including thixotropic stiffening of designed fresh SCC in comparison with its formwork pressure with constant, fast casting speed. The aim of the study was to determine the effect of the type of cement, w/c ratio, chemical admixtures and time on the rheological properties of selected SCC. The aim was also to determine influence of rheological properties on value of SCC formwork pressure. It will allow to better understand and describe the nature of the previously observed decreasing formwork pressure using self-compacting concrete. The rheological characteristic and thixotropic behaviour of SCC were determined by using a rheometer Viskomat XL and technical tests, air content by pressure method and formwork pressure by the element imitating the column with dimensions of 0.20x0.20m and a height of 1.20 m with specially designed pressure sensors.