Prediction of Concrete Pumping: Part Ⅰ-Development of New Tribometer for Analysis of Lubricating Layer

摘要

The character of the lubricating layer formed near the wall of a pipe during the flow of pumped concrete is a dominant factor facilitating concrete pumping. To predict flow rates of concrete transported by pumping, it is necessary to measure the Theological properties of the lubricating layer before pumping. In this paper, a new version of a test instrument called a tribometer is developed by considering the level of shear rate that induces the lubricating layer during real pumping. A test method is also suggested based on numerical simulation of the shear flow inside the tribometer and, finally, equations capable of transforming the values measured in the new tribometer into the rheological properties of the lubricating layer are derived. Work in this paper will be extended in a subsequent paper in which full-scale pumping tests will be performed, and predictions for concrete pumping based on the measurements of the new tribometer will be verified from comparisons with the test results.