Resumo

FRANCA, Marylinda Santos de; CARDOSO, Fábio Alonso  e  PILEGGI, Rafael Giuliano. Mixing behavior of mortars evaluated by rotational rheometry. Ambient. constr. [online]. 2012, vol.12, n.2, pp. 165-174. ISSN 1678-8621.  http://dx.doi.org/10.1590/S1678-86212012000200011.

The main step of mortar processing consists in mixing the powder materials with water. The addition of the liquid into the granular system promotes a set of agglomeration and dispersion phenomena, which result in variations of the forces required to shear the mortar during mixing. Previous studies demonstrated that is possible to measure the mixing energy through torque vs. time curves. The aim of this work is to evaluate the influence of mixing time on mixing and rheological behaviors of a rendering mortar. The material was mixed for different times on a rotational rheometer (17, 47, 87 and 297 s) and then submitted to 3 consecutive shear cycles. At short times, the resulting mixing energy was low and unable to break the agglomerates and to homogenize the system; hence the mortar was rheologically unstable and less fluid. On the other hand, the 297-second mixing was efficient, producing a fluid and stable mortar.

Palavras-chave : Mixing; Mortar; Rheology.