Rheological model for self consolidating concrete

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► We correlate results from the slump-flow test including final diameter, time to 50 cm and time to final diameter to dynamic segregation.

► Segregation was determined by measuring the radial aggregate distribution.

“Prediction of Creep, Shrinkage and Temperature Effects in Concrete Structures.” ACI 209R-92, Re-approved 1997, Farmington Hills, MI.

“Standard Prac- tice for Selecting Proportions for Normal, Heavyweight, and Mass Concrete.” ACI 211.1R-91, Re-approved 2002, Farmington Hills, MI.

“Self- Consolidating Concrete.” Emerging Technologies Series (ETS), ACI 237R-07, Farmington Hills, MI.

“Effect of Coarse Aggregate Charac- teristics on Lateral Pressure Exerted by Self-Consolidating Concrete.” ACI Materials Journal, V.

This paper presents the development of a rheological model for self-consolidating concrete (SCC).

The developed model is based on the paste rheology criteria, which include minimum apparent viscosity, minimum flow, and optimum flow-viscosity ratio to achieve self-consolidating concrete with satisfactory segregation resistance and deformability.

Many studies have recently been performed to understand and optimize the pumping process and identify the main differences between pumping of conventional vibrated concrete and self-consolidating concrete (SCC).

Depending on their rheological behaviour, these pastes will be used later to study the stability of coarse aggregates.

The major aim of this paper is to show that empirical tests such as spread and flow time are suitable to characterise the rheological behaviour of cement pastes instead of more complex ones. viscosity and shear yield stress, are well correlated with empirical test results in the range of flowable mixes.

“Variation of Formwork Pressure with Thixotropy of Self-Consolidating Concrete.” ACI Materials Journal, Vol.

“Ultra-High Per- formance Fiber-Reinforced Concretes.” Groupe de travail BFUP, Paris, France.

Pumping of concrete is the fastest and most efficient way to place concrete inside a formwork.

In the past, several practical guidelines were developed to optimize concrete mix designs, to predict pumping pressure or to optimize the layout of pumping circuits [].

In many cases, the concrete undergoes a large shear rate in the pipe, thus (re-)dispersing cement particles.

This is expected to be the main cause of the observed decrease in plastic viscosity, V-Funnel flow time and pumping pressure resulting from increased flow rate or pumping time.

This kind of concrete is of great interest and has gained wide use especially in the case of difficult casting conditions such as heavily reinforced sections.

From a rheological point of view, the use of a Viscosity Enhancing Admixture (VEA) along with an adequate superplasticizer content enables to ensure high deformability and stability.

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