Evolution of Concrete/Formwork Interface in Slipforming Process
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In a slipforming process, concrete is continuously poured and the formwork simultaneously raised so that the older concrete at the bottom supports the fresher at the top after a few hours of hydration. Such a complex process has to be industrially optimized to ensure the quality surface of concrete. The objective of the present work is to study the evolution of the concrete/formwork interface at very early age.
An experimental device has been designed in order to measure the evolution of the friction at this interface during the first hydration period. With cement hydration and thus water consumption, pore water pressure decreases and creates suction which could increase granular stress on the formwork. The role of pore water pressure on formwork friction is investigated. The first hydrates may also bond to the surface and create a strong adhesion at the same time.
KeywordsInterface Friction Slipforming
The authors are thankful to Agata M. Gajewicz and Prof. Peter McDonald (University of Surrey) for allowing us measuring the water consumption with relaxometry NMR and there useful feedbacks.
The authors also wish to thank Alexandre Menguy which made the drawings of the experimental device.
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