Experimental developments of the squeeze-flow test for building materials

Reference	Presenter	Authors (Institution)	Abstract
04-075	Fábio Alonso Cardoso	Cardoso, F.A.(Escola Politécnica - Universidade de São Paulo); John, V.M.(Escola Politécnica - Universidade de São Paulo); Pileggi, R.G.(Escola Politécnica - Universidade de São Paulo);	The squeeze-flow rheological technique is based on the compression of a cylindrical sample between parallel plates and is widely used to determine the flow properties of food, pharmaceuticals, composites, ceramics and other suspensions. Its geometry change during gap reduction makes the method particularly interesting for building materials, as it creates flow conditions similar to those involved in processing and application of pastes and mortars (e.g. spreading; squeezing between bricks; extrusion of cement-based materials). This work reports a summary of experimental developments on squeeze-flow for the evaluation of different building materials. The research conducted over the past decade led to the creation of the Brazilian standard test method of squeeze-flow applied to rendering and masonry mortars (ABNT NBR 15839:2010). The paper describes the possible configurations of the test (geometry set-up, velocity, displacement, roughness), the experimental procedures used for pastes (gypsum, hydrated lime, cement) and for different types of mortars (rendering, masonry, adhesive, fiber-containing). Furthermore, complementary techniques applied for the assessment of pressure evolution on the sample during flow (interfacial pressure mapping) and phase separation induced by the test (microwave drying) are presented. Examples of results showing the influence of mixing method, admixtures (air entraining and cellulose-based viscosity modifier) and mix design on the flow behaviour of mortars are discussed. Finally, it compares rheological parameters of mortars determined by squeeze-flow and by rotational rheometry.<!--[if gte mso 9]>
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