Viscosity equation for fresh concrete

Abstract

For robotization of concreting, it is extremely important to establish a prediction equation for flow and deformation of fresh concrete due to various external forces such as dead weight, pressure, and vibration. Conventionally, it has been recognized that a Bingham model conforms well as the rheological model of wet-consistency concrete, but the plastic viscosity and yield value must be accurately quantified. However, the methods of measuring these physical values are generally complicated and are unsuitable for practical purposes. Therefore, an equation for calculating is proposed. As a result of examining the applicability of the viscosity equation proposed with approximately 60 varieties of concrete, the ratios of estimated to measured values of plastic viscosity average approximately 1.0 with coefficient of variation less than 10 percent, and it is ascertained that the equation can be satisfactorily used. Since yield value will be required besides plastic viscosity for predicting the behavior of fresh concrete, a convenient method of estimating this value is also described.