These experimental devices are used to study pressure drop over time.The sensors are placed at varying heights and each university uses different height columns.This small displacement of the sensor causes the sensor to lose contact with the concrete, and this results in errant measurements of lateral pressure on the form material.A comparison of a plain cardboard tube, one with a plastic liner, and 2 PVC pipe configurations are shown in Figure 5. Effect of Formwork Material on Measured Lateral Pressure top Many factors can affect the formwork pressure generated in the process of pouring SCC.Additionally, the highest pressure was reached long before the pour was finished.
The general procedure is to fill the cylinder and then apply an ever increasing load until a pre-determined maximum load representing a particular column height.
These proved to be problematic in studying formwork pressure.
The cardboard material absorbs moisture from the concrete and swells.
Figure 2 and Figure 3 show results of various mixtures from tests performed at Sherbrooke and UIUC, respectively. Example of Results from UIUC An alternative laboratory set up is used by researchers at Northwestern University.
Their testing apparatus utilizes a short column of concrete, 300 mm, in a steel mold. A loading frame is used to apply a load on the top of the column of concrete to simulate the effect of a much larger column of concrete.