Concrete Flowability Tester

Description

The concrete flow test measures how fast and how far a concrete mix will flow on its own. The test is performed by pouring some of the concrete into a cone on a non-porous plate. Once the cone is full, the cone is lifted in a straight vertical line to allow the concrete to flow out. The 700 mm square flow table is hinged to a rigid base, proved with a stop that allows the far end to be raised by 40 mm. A cone, similar to that used for slump testing but truncated, is filled with concrete in two layers. Each layer is tamped 10 times with a special wooden bar and the concrete of the upper layer finished off level with the top of the cone. Any excess is cleaned off the outside of the cone. The cone is then raised allowing the concrete to flow out and spread out a little on the flow table. The table top is then raised until it meets the stop and allowed to drop freely 15 times. This causes the concrete to spread further, in a roughly circular shape. The flow diameter is the average of the maximum diameter of the pool of concrete and the diameter at right angles. As well as getting an accurate measurement of the workability of the concrete, the flow test gives an indication of the cohesion. A mix that is prone to segregation will produce a non-circular pool of concrete. Cement paste may be seen separating from the aggregate. If the mix is prone to bleeding, a ring of clear water may form after a few minutes.