The squeezing test: a tool to identify firm cement-based material's rheological behaviour and evaluate their extrusion ability

The squeezing test is used in this paper as a rheological behaviour identification tool of cement-based materials in order to evaluate the extrusion ability. Experimental flow curves are obtained for firm cement pastes and fine sand firm mortars using two different compression speeds. These tested products may be considered as frictional plastic materials. Using the proposed testing method, two important aspects are discussed. On one hand, it is shown in this paper that the mortars bulk and apparent friction factors increase with sand addition proportion. On the other hand, cement paste's apparent yield shear stress increases at low compression speed because of fluid drainage through the granular skeleton and sample hardening. Some pictures obtained after squeezing test are used to illustrate this drainage phenomenon. Finally, some mortar mix design indications are proposed according to extrusion criteria based on rheological conditions.