Measurement systems for determining formwork pressure of highly-flowable concrete

This paper offers recommendations regarding test set-ups and measurement systems that can be used for laboratory evaluation and field testing of lateral pressure exerted by flowable concrete and self-consolidating concrete (SCC). Test results indicate that pressure sensors placed flush with the inner surface of the formwork can be used to assess the lateral pressure exerted by plastic concrete. The pore-water pressure resulting from the fluid phase of concrete can be evaluated using pore-water pressure sensors similar to the ones employed in soil mechanics. The sensors can be attached at different heights onto rigid formwork system to monitor changes in pressure with time. Sono-tubes made of cardboard are found not to be suitable for monitoring concrete pressure variations because of their flexibility which leads to erroneous values. A pressure column was developed to evaluate lateral pressure and its variations with time exerted by fresh SCC for heights of up to 10 m. Another system consisting of strain gages welded onto steel anchored bars inserted in the formwork was tested and compared to the pressure transducers system.