Influence on Type of Cement on the SCC Formwork Pressure during and after Casting

Abstract

Formworks for SCC are usually designed under the assumption of full hydrostatic pressure. Nevertheless, current research is attempting to explain the mechanism of this phenomenon as observed pressure usually is at the lower lever than expected. This causes formworks for SCC are usually overdesigned. It was noticed the rheological properties of fresh concrete might be a key to predict the SCC formwork pressure. Therefore, knowing the influence of fresh concrete properties on formwork pressure will enable to design formworks more efficiently. This paper presents the influence of type of cement on formwork pressure caused by SCC. Mixes were design under the assumption of equal dispersion ratio. Three types of cement were investigated: portland, blast furnace and composite cement with a different w/c ratio (0.30, 0.40) and in presence of carboxyl ethers superplasticizer. Formwork pressure was determined on the element imitating a column with dimensions of 0.20x0.20m and a height of 1.20 m with casting speed of 7 m/h. Results show the formwork pressure was registered at the lower than hydrostatic level. Rheological properties had an influence on formwork pressure. It was noticed the different cement types had an influence on rheological properties. Lateral pressure reduction over time was observed with the intensity depending on the cement.