Concrete Workability

Angles Flow Box Test

The Angles flow box test (Scanlon 1994; Wong et al. 2000) attempts to simulate typical concrete construction in order to characterize the ease with which concrete can be placed. The test measures the ability of concrete to flow under vibration and to pass obstructions.
The device consists of a rectangular box mounted on a vibrating table. Two adjacent vertical partitions are placed in the middle of the box to divide the box in half. The first partition consists of a screen of circular bars that are spaced so that the openings between the bars are the size of the maximum aggregate. The second partition is a solid, removable plate that initially holds concrete on one side of the box prior to the beginning of the test. After concrete has been loaded on one side of the box, the solid partition is removed and the vibrating table is started. The time for the concrete to pass through the screen and form a level surface throughout the box is recorded. The amount of bleeding and segregation that occurs during vibration can be observed visually.

Very little data is available on the validity of the test and on interpretation of the test results. The test method would not be appropriate for very low slump mixes. For highly flowable concrete mixtures, vibration may be unnecessary. A similar concept is used to test the workability of selfcompacting concrete.
• The test method represents actual field conditions. It is a dynamic test that subjects concrete to vibration.
• The ability of concrete to pass obstructions and resist segregation is assessed.
• The test is bulky and would probably not be appropriate for field use.
• The test result is likely a function of both yield stress and plastic viscosity, although these values are not directly recorded.

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