Optimized protocol to measure the flow curve of cement paste and its verification with gravity-induced flow simulation

Abstract

To quantitatively evaluate the flowability of freshly mixed concrete, fundamental research was conducted on the basis of rheology. Comparing field experiments with the rheological properties of cement paste, the measuring protocol for non-Newtonian fluid having thixotropy is proposed and its flow simulation is verified. For the purpose, the rheological property of various cement paste samples is measured by parallel plate sensor under various conditions, which includes storage state of material, volume of the mixture, type of mixer, and dosage of superplasticizer. Throughout both the reproducibility test and computational simulation analysis, the protocol for measuring the rheological properties is optimized to describe gravity-induced flow such as slump flow of concrete. The volume of fluid technique is used for the flow simulation, which solves the problems assuming that the cement based material is homogeneous fluid. Simulation of the gravity-induced flow needs the flow curve the rheological properties should be measured including from 0.1 to 50 s-1. Our research was conducted by 10 steps, and each step takes about 5 s. In order to prevent the slippage, the sandpaper was attached on the plates. In the standard of channel flow, the results have corresponding approximately between real and simulation.