Form pressure characteristics of self-consolidating concrete used in repair

Abstract

This paper aims at assessing the lateral pressure exerted by self-consolidating concrete (SCC) on single-sided vertical formwork during repair work. Reinforced concrete repair wall elements measuring 5.6 ± 0.3 m in height and 180 mm in width were cast using SCC mixtures having different thixotropic characteristics at casting rates varying from 6 to 9.5 m/h. Results showed that the actual field pressure values are substantially lower than the equivalent hydrostatic pressure, varying from 60% to as low as 34% at the end of casting. This was attributed to the SCC structural build-up coupled with the presence of vertical/transverse reinforcing bars, arching effect in confined and tall repair sections, and increased friction between the concrete and existing repair substrate. The use of a 1.1-m high experimental PVC column was found appropriate to mimic the decay of lateral pressure observed in the repair wall elements, making it relevant to predict the effect of concrete restructuring on casting rate. Such data can be of interest to tailor the mixture proportions and enhance safety aspects related to casting slender repair sections with SCC.