Rheological behavior of mortars under different squeezing rates

• Published in: Cement and concrete research Vol. 39; no. 9; pp. 748 - 753
• Main Authors: Cardoso, Fábio A., John, Vanderley M., Pileggi, Rafael G.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.09.2009; Elsevier
• Subjects: Applied sciences; Buildings. Public works; Concretes. Mortars. Grouts; Exact sciences and technology; General (composition, classification, performance, standards, patents, etc.); Materials; Mortar (E); Rheology (A); Squeeze flow; Rheology (A); Mortar (E); Squeeze flow; Squeezing; Mortar; Air content; Rheology; Construction materials; Water content; Experimental study; Concrete compaction
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/j.cemconres.2009.05.014

In the present work the squeeze flow technique was used to evaluate the rheological behavior of cement-based mortars containing macroscopic aggregates up to 1.2 mm. Compositions with different water and air contents were tested at three squeezing rates (0.01, 0.1 and 1 mm/s) 15 and 60 min after mixing. The mortars prepared with low (13 wt.%) and usual water content (15 wt.%) presented opposite behaviors as a function of elapsed time and squeezing speed. The first lost its cohesion with time and required higher loads when squeezed faster, while the latter became stiffer with time and was more difficult to be squeezed slowly as a result of phase segregation. Due to the increase of air content, the effects of this compressible phase became more significant and a more complex behavior was observed. Rheological properties such as elongational viscosity and yield stress were also determined.