Slipforming - Materials effect on friction

Abstract

Slipforming is a construction method for concrete and it is especially suited for tall constructions with simple geometry. This method have occasionally caused lifting cracks and other surface damages, due to the friction between the slipform panel and the concrete has become to high. The thesis will look at how the choice of material composition in concrete mixes in the combination of a given slipform rate would affect the friction between the slipform panel and concrete. The goal is also to verify that the test rig will reproduce the same results with the same concrete mix. In addition there will be tested ultra-high performance concrete to see if it can be used in slipforming. A total of 10 concrete mixes have been tested in the slipform rig, a reference mix, increased content of silica, air entrainment mix and a mix with lowered water binder ratio, in addition ultra-high performance concrete. The results indicate that the slipform rig is able to reproduce results. The max net static and kinetic lifting stress is increased with a higher silica content and with a lower water binder ratio. With increased air content the max net static and kinetic lifting stress is lowered. When compared to the reference mix..