＊ Associate Professor, Department of Civil Engineering, College of Industrial Technology, Nihon University＊＊ Associate Chief Research Engineer of National Federation Ready-Mixed Concrete Industrial Associations, Central Reserch This study aims to help improve efficiency of concrete pumping. A thin film of water can be assumed to be present at the interface between the concrete and the pipe wall and acting as a lubricating layer during pumping. With a two-layer flow model consisting of the concrete and the water film applied to the concrete flow in pipes, the concrete flow rate can be given as a sum of the Bingham fluid flow rate, the flow rate of concrete due to slip and the volume of the water film. The following method was studied in this research for measurement of rheological quantities, using the two-layer flow analytical model. The amount of dehydration corresponding to each pressure condition at the pump outlet was measured by using a pressure bleeding tester, the thickness of the water film occurring on the pipe wall surface and the slip velocity of the concrete were estimated from the dehydration values, then, the Bingham fluid flow rate was determined from the flow rate measured by a pipe viscometer, and rough values of plastic viscosity and yield stress were calculated by using three different sets of the Bingham fluid flow rate and pressure gradient. The results were found to be close to those of measurement by a rotating viscometer, which suggested the usefulness of the pipe viscometer in measuring the rheological quantities. This paper is basically an English translation with some revisions and additions of “Measurement of Rheological Quantities Using a Pipe Viscometer” by Yamanouchi, K., Yamaguchi, S. and Itoh, Y. published in Japanese in 2017 in the Proceedings of the Japan Concrete Institute, 39 (1), 1159-1164.Keywords: Concrete Flow in Pipes, Rationalization of Concrete Pumping, Rheological Quantities, Pipe Viscometer, Rotating ViscometerRecent concrete structures tend to have higher densities of reinforcement and use highly complex pipe routes for pumping, increasing the need for rationalization of concrete construction and enhancement of its quality.1) ~5) For enhanced quality of concrete construction, there has been an increase in the use of high-flow concrete which contains air-entraining high-range water-reducing agents and thickeners to improve resistance to material separation.6) Pumping the concrete of this type in a complex piping often requires test pumping to Laboratorydetermine a suitable pipe diameter and pump capacity. To reduce the labor required for test pumping, it is necessary to know fluidity and mechanical properties of the concrete flowing in a pipe.Concrete in the fluid state is known to behave like a Bingham fluid. That was why an equation based on the Buckingham equation was used for the in-pipe flow rate in previous studies7) ~12), with slip on the pipe wall taken into account. Since the slip on the pipe wall here assumes the liquid friction state for the concrete at the pipe wall, it is necessary to obtain plastic viscosity, yield stress, viscous friction coefficient and adhesion force as mechanical （Received June 9, 2021）Abstract─ 1 ─日本大学生産工学部研究報告Ａ2021年 12 月 第 54 巻 第 ２ 号1. IntroductionArticleShin YAMAGUCHI＊ and Koichiro YAMANOUCHI＊＊A Study on Measurement of Rheological Quantities of Fresh Concrete Using a Pipe Viscometer
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