An adequate rheological characterization of cement-based formulations is absolutely necessary, in order to develop cement extrusion technology, by the use of non-traditional testing methods specifically developed for this purpose. Indeed, current rheological methods proposed for fresh concrete, mortars and pastes are applicable to highly flowable mixes, but it is not possible to use them for the characterization of dense, cohesive and very dry compositions (such as the cement mixes used for extrusion). The rheological test methods which have been proposed in the last ten years for cohesive cement-based compositions were initially developed for traditional materials (plastics, rubber, clays, soils and metals); in this case, the complexity of the cement chemistry is to be taken into account. In this paper, some useful test methods adopted for the rheological characterization of cement-based compositions for extrusion will be described, and some examples of characterization results will also be reported.
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