DETERMINATION OF RHEOLOGICAL PARAMETERS OF LIME PASTES WITH CONSIDERATION OF THE WALL-SLIP EFFECT

The rheological measurements of the lime pastes were performed with use of the coaxial rotational viscometer Haake Viscotester Vt550, with different sensor systems. Obtained pseudo-curves of flow tau (gamma(p)) indicated a non-Newtonian behavior of lime pastes, which required the correction to the actual flow curves tau (gamma). The corrected flow curves, for the same water-to-lime ratios W/L, but measured with different sensor systems do not coincide with each other, throughout the range of concentrations tested. This indicates the occurrence of the wall-slip effect. Therefore correction of flow curves was performed, according to Kiljanski method [1989], to obtain a one flow curve for two different sensor systems. The approximation of flow curves was carried out with use of the tri-parametric Herschel-Bulkley model. An evaluation of the error in the determination of rheological parameters without taking into account the wall-slip effect was performed.