1. OBJECTIVE
The consequences of applying different shear rates, after a
rest period, on the rheological properties of cement paste
with SCC consistency has been investigated during
pumping. Determining the rheological properties of cement-
based materials has enabled significant advancement in
different aspects of concrete science, including mix design,
fresh properties and placement. In some cases, e.g.
intensive mixing and pumping, concrete is subjected to
large shear rates that effect rheological properties of
concrete.
BACKGROUND
• Due to the complex composition of concrete, its fresh
properties depend on the shear history.
• Shear rate values of 30 to 60 s-1, in bulk SCC, have
been reported during pumping. whilelayer, formed near
the pipe wall has significantly lower viscosity and the
shear rate in this layer would be several 100 s-1.
• Reological properties are expected to be largely
influenced by pumping or shearing.
METHODS
Mix design for 1.5 L
• Ternary binder:
25% class C fly ash, 2.5% silica fume
• SP (PCE) adjusted for mini SF = 330 mm
Testing Procedure
Influence of Applied Maximum
Shear Rate on Rheological
Properties of Cement-Paste
with SCC Consistency
Azadehalsadat Asghari, Dimitri Feys
Department of Civil, Architectural and Environmental Engineering, Missouri University of Science &
Technology, Rolla, MO, United States
RESULTS
Raw Data
Rheological tests on cement paste with SCC consistency have revealed that the pre-shear has a significant effect
on the rheological properties. From the raw data extracted by Anton Paar MCR 302 Rheometer, it can be
concluded that:
• By increasing the maximum applied shear rate, both the plastic viscosity and yield stress decrease.
• The yield stress value at a pre-shear of 12.5 s-1 is approximately 21% larger than the corresponding yield
stress value at 100 s-1, while a difference of 34% is observed for the viscosity.
I
Fit with Infinite Shear Data Fit with Log Function
SUMMARY
Rheological tests on cement paste with SCC consistency
have revealed that the pre-shear has a significant effect on
the rheological properties. From the results and analysis, it
can be concluded that:
• The yield stress and plastic viscosity decrease
significantly with increasing shear rate applied during the
pre-shear period. This can be attributed to the additional
dispersion the particles undergo when increasing the
applied shear rate.
• Applying a decreasing exponential function, based on
infinite shear rheological properties was deemed
adequate to fit the data, but hindered the repeatability of
the results.
• Logarithmic functions, with the yield stress or viscosity
value at a pre-shear of 100 s-1 as reference, fit the data
well and result in good repeatability.
ACKNOWLEDGEMENTS
The authors would like to acknowledge the RE-CAST Tier-
1 UTC for the financial support and the center for
infrastructure of engineering studies (CIES) at Missouri
S&T for the technical support of this project.
100s-1
50s-1
25s-1
12.5s-1
0.9
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
0 20 40 60 80 100
RelativeYieldSress(-)
Applied Pre-Shear (s-1)
YS R1
YS R2
YS R3
YS R4
 
 B
Ae
  1,00
 
 D
pp Ce
  1,
0.9
1.1
1.3
1.5
1.7
1.9
2.1
0 20 40 60 80 100
RelativePlasticViscosity(-)
Applied Pre-Shear (s-1)
PV R1
PV R2
PV R3
PV R4











100
log1100,00
 
A











100
log1100,
 
App
0.9
0.95
1
1.05
1.1
1.15
1.2
1.25
1.3
0 20 40 60 80 100
RelativeYieldSress(-) Applied Pre-Shear (s-1)
YS R1
YS R2
YS R3
YS R4
0.9
1
1.1
1.2
1.3
1.4
1.5
0 20 40 60 80 100
RelativePlasticViscosity(-)
Applied Pre-Shear (s-1)
PV R1
PV R2
PV R3
PV R4
• Quantifying the influence of the different pre-shear on
the plastic viscosity and yield stress by represent the
results by a simple set of parameters,
• Applying Two types of functions (decreasing
exponential and logarithmic) to normalized data.
• Normalizing the yield stress and viscosity values by
their extrapolated values at infinite shear rate for the
exponential curves,
• Normalizing the yield stress and viscosity values by
the respective value at 100 s-1 shear rate for the log
curves.
In polymer rheology: zero shear
and infinite shear viscosity
Fit with log functions, relative
to properties at 100 s-1
0
10
20
30
40
50
60
70
80
90
100
29 31 33 35 37 39
AppliedShearRate(S-1)
Time after cement-water contact (min)