1. Influence of Addition Time of
Superplasticizer on Rheological Properties
of Self-Consolidating Cement Paste
Azadeh Asghari
Cookeville 2014, July 9-11
5th Advances in cement-based Materials

2. Goals of Research Project
l Robustness is the ability of SCC to maintain fresh properties
due to small changes in the content of ingredients of the
mixture.
l Main problem of practical application of SCC is robustness.
l The project aims to understand the influence of the mixing
procedures and Addition sequence on the robustness of
SCC-mixtures.
l The robustness mainly be investigated by means of
rheology, specific parameters investigated are:
-Mixing energy, by varying mixing time and mixing speed.
-Addition time of the superplasticizer

3. Outline
l Goals of Research
Project
l Rheometer
l Concrete Rheology
l Mix Designs
l Mixing Procedure
l Plastic Viscosity
l Conclusions

4. Rheometer
l The Anton Paar MCR 302 Rheometer
l With Coaxial Cylinder
l Control Temperature at 23 degree
Pre-sheared to eliminate thixotropy

5. Concrete Rheology
l Rheology is defined as the science of deformation matter.
l Concrete rheology measurements are typically expressed in terms
of the Bingham model, which is a function of:
– Yield stress: the minimum stress to initiate or maintain flow (related to
slump)
– Plastic viscosity: the resistance to flow once yield stress is exceeded
(related to stickiness)
The Bingham Model
Slope= plastic viscosity

6. Mix Designs
l Powder Mix Design (Reference) 1.5 liter:
l VMA Mix Design (Reference) 1.5 liter:
Cement type I/II
(g)
Lime Stone Filler
(g)
Water
(g)
SP1
(g)
W/C W/P
1210.8 1210.8 665.9 5.2 0.55 0.275
Cement
type I/II
(g)
Silica
Fume
(g)
Fly Ash
C
(g)
Water
(g)
SP2
(g)
VMA
(g)
W/C W/P
1443.3 50.4 499.3 759.4 9.690 1.250 0.53 0.38

7. Mix Designs
l VMA Mix without VMA
l VMA Mix with different type of SP
l VMA Mix without FA & SF (replaced by volume
of cement)
l VMA Mix with Limestone filler without FA & SF
(Replaced by volume of Limestone filler)

8. Mixing Procedure of Addition time of SP
During first
1 minutes
After
2minutes
30sec
100% of SP
50% of SP
0% of SP 100% of SP
50% of SP
0% of SP
With Water After Water

9. Outline
l Goals of Research Project
l Concrete Rheology
l Rheometer Procedure
l Mix Designs
l Mixing Procedure
l Plastic Viscosity
For Powder-type and VMA-type at Different Addition time of SP
Presence of VMA
Type of SP
Presence of Silica Fume & Fly Ash
Presence of Limestone Filler
l Conclusions

10. Plastic Viscosity
Viscosity at different addition time of SP
Mix design 1
VMA Mix
Powder Mix
Change of water
equivalent 10 l /m3

11. Plastic Viscosity
Presence of VMA
∆=0.084 ∆=0.074

12. Plastic Viscosity
Type of SP
∆=0.076
∆=0.074

13. Plastic Viscosity
Presence of Silica Fume & Fly Ash
∆=0.084
∆=0.085

14. Plastic Viscosity
Presence of Lime stone Filler
∆=0.074 ∆=0.045

15. Plastic Viscosity
Viscosity at different addition time of SP
Mix design 1
VMA Mix
Powder Mix
Change of water
equivalent 10 l /m3

16. Conclusions
l Robustness is a significant problem slowing down the
application of SCC. The variations in rheological
properties of SCC-cement pastes were investigated by
changing the addition time of SP.
l For the VMA-type mix design studied, the rheological
parameters are more sensitive to the addition time of
SP, relative to a variation in water, while for the
Powder-type mix design the opposite is observed.
l Tests indicated that the limestone filler has a more
significant role, compared to the presence of VMA, the
type of SP and the use of silica fume and fly ash.

17. Questions??
More info? aaz85@mst.edu