RHEOLOGICAL CONSTANTS MEASUREMENT OF CEMENT PASTE AND CEMENT PASTE FLOW ANALYSIS BY MARKER PARTICLE VISCO-PLASTIC FINITE ELEMENT METHOD

In order to conduct flow analysis of cement paste, mortar and concrete, it is important to obtain rheological constants representing the flow characteristics of the material. In this study, we measured cement paste's rheological constants by using rotational viscometer. Here, it was measured in consideration of flow history on cement paste. Furthermore, in this study, we derived the flow constitutive equation of the cement paste and proposed a marker particle visco-plastic finite element method. Using this marker particle visco-plastic finite element method, simulation of flow test of cement paste was attempted. The results obtained from the experimental study and analytical study of this research can be summarized as follows. Using a rotational viscometer, the flow curve of cement paste was measured for various shear conditions. It was confirmed that the flow curves of all cement paste samples can be approximated by the Bingham model under all shear conditions. And the obtained flow curve was approximated by the Bingham model, and the rheological constants (yield value and plastic viscosity) of the paste sample was determined. Thixotropy was confirmed in the flow characteristics of the cement paste sample from the obtained flow curves and rheological constants. The cement paste was regarded as a visco-plastic fluid and derived the flow constitutive equation of visco-plastic fluid using overstress theory. The obtained flow constitutive equation considers non-Bingham characteristic, flow history, and pressure dependency of yield value. It was confirmed that the flow curves of cement pastes differing depending on shear conditions can be expressed by the proposed flow constitutive equation. Marker particle visco-plastic finite element method was used to analyze the flow test of cement pastes. The results obtained by the analysis agreed well with the experimental results. Therefore, the marker particle visco-plastic finite element method and the rheological constants are effective