Vibro-extrusion: a new forming process for cement-based materials

Abstract

Extrusion is a common forming process for a wide range of materials (food, polymer, clay, metal), although it is not yet a common way to form cement-based materials on an industrial scale. This is both explained by the heterogeneity (large range of grain size) and the specific rheological behaviour (frictional behaviour due to high solid volume fraction) of such materials. Recent studies have highlighted the predominance of the filtration phenomenon during the extrusion flow of firm cement-based materials. Such a filtration leads to process blockage and prohibits its utilisation in industrial settings. In the present study the introduction of a vibration system to the extruder in order to inprove the extrusion flow was investigated. The effects of such external excitation on the rheological behaviour of a firm extrudible cement-based paste (yield stress reduction without losing retaining shape properties) were examined and some extrusion tests (ram and screw extruders) were performed to show the potential of a vibration/extrusion coupling.