Rheological Estimation of Flowing Mortar with a Superplasticizer

The fluidity of self compacting concrete is influenced by the fluidity of the composed mortar. This paper discusses the rheological estimation of the fluidity of high-flowing mortars with superplasticizers. The character of fine aggregates is considered the most effective factor on mortar fluidity. The applicability of the viscosity equation proposed by Mori and Ototake for condensed suspension liquids to highly-flowing mortar is discussed. Mortars were tested with different volume concentration of fine aggregate-suspended in highly-flowing paste. The result from rheological test using a Brookfield type viscometer indicated good agreement with the equation. Provided that the fluidity of the mortar behaves as a Bingham fluid, it can be estimated by plastic viscosity and yield value. These rheological tests were applied to two types of highly-flowing mortars composed of self compacting concrete mixtures ranging from 60 to 70 cm of slumping flow value. The effects of fine aggregate fluctuated with differences in water content, sand content and sand grading of the basic mortar. Test results showed that the character of the sand remarkably affects the fluidity of highly-flowing mortar.