Influence of the Rheological Properties of SCC on the Formwork Pressure

Formworks for self-compacting concrete (SCC) are commonly designed under the assumption of full hydrostatic pressure. However, current research shows that SCC's design pressure could be reduced, if the concrete's rheological properties were taken, into account. Knowing the relationship between the properties and the pressure, we can prevent formwork overdesign. This research was based, on the assumption that fresh concrete can be described as a Bingham fluid. This paper presents the correlations between static and dynamic yield stress, and lateral formwork pressure. Measured rheological parameters were compared to standard technical concrete tests. Formwork pressure were determined on the element imitating a column with dimensions of 0.20 x 0.20 m and a height of 1.20 m with two casting speeds 1 and 7 m/h. Three types of cement, 2 superplasticizers, and 2 w/c ratios were used. A correlation between rheological parameters and pressure reduction over time was observed. Based on our results we propose a methodology and testing sequence applicable in practice.