Investigating whether a correlation exists between rheology and empiricism for various steel fibre self-compacting concrete mixtures with additional cementitious additions (such as PFA and GGBS).

1. The Rheological Characteristics of SFRSCC with
PFA and GGBS
CONCRETE RHEOLOGY CONCRETE WORKABILITY
CORRELATION

2. Objectives
 Mix Design and Modelling
 Hershel-Bulkley model
 Rheological and Empirical Parameters
 Statistics
 Workability retention
 GGBS and PFA
 Rheology and Workability
 Influence of steel fibres
 Influence of time
Torque (N/m)
T = To + ANb
Slope = h
Speed (rev/s)
g
Linear approximation of
Hershel-Bulkley model
Shear stress, τ
τ = τo + Kγn
Slope = μ
Shear strain rate, γ
τo
Linear approximation of
Hershel-Bulkley model

3. Mix Design and Testing Sequence
REF REF REF
Component
Series 1
(kg/m3)
Series 2
(kg/m3)
Series 3
(kg/m3)
CEM II/A-L 580 406 290
Limestone filler 20 20 20
GGBS - - 290
PFA - 174 -
Fine aggregate 1020 1020 1020
Coarse aggregate 630 630 630
Superplasticiser (Glenium 27) 12.5 12.5 12.5
Stabiliser (RheoMatrix 100) 78 78 78
Water 215.5 215.5 215.5
Steel fibre type
Steel fibre
content
SCC-Series
1 (R 65/35)
SCC-Series
2 (R 65/35)
SCC-Series 3
(R 65/35)
0 (kg/m3) (REF) o o o
5 (kg/m3) o o o
10 (kg/m3) o o o
15 (kg/m3) o o o
20 (kg/m3) o o o
25 (kg/m3) o o o
30 (kg/m3) o o o
Sequence
Regime-1 (15 min
after addition of
water)
Regime-2 (30 - 65
min after addition of
water)
Regime-3 (65 - 95
min after addition of
water)
1 TWT TWT TWT
2 Slump flow Slump flow Slump flow
3 L-box L-box L-box
4 J-ring J-ring J-ring

4. Hershel-Bulkley Curve Fitting
R² = 0.998
R² = 0.9958
R² = 0.9645
7
6
5
4
3
2
1
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3
Torque (N/m)
Speed (rev/s)
SCC-1, 15 min
SCC-1, 45 min
SCC-1, 75 min
Hershel-Bulkley, 15 min
Hershel-Bulkley, 45 min
Hershel-Bulkley, 75 min
Poly. (SCC-1, 15 min)
Poly. (SCC-1, 45 min)
Poly. (SCC-1, 75 min)

5. Effect of PFA and GGBS on Rheology and workability
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
SFRSCC
SFRSCC with PFA
SFRSCC with GGBS
0 5 10 15 20 25 30
Rheological parameter, g
Steel fibre content (kg/m3)
7
6
5
4
3
2
1
0
SFRSCC
SFRSCC with PFA
SFRSCC with GGBS
0 5 10 15 20 25 30
Rheological parameter, h
Steel fibre content (kg/m3)
80
70
60
50
40
30
20
10
0
STD: 1.3
SFRSCC
SFRSCC with 30% PFA
SFRSCC with 50% GGBS
STD: 1.08
STD: 1.5
0 5 10 15 20 25 30
7-Day strength (N/mm)
Steel fibre content (kg/m3)

6. Empirical and Rheological Parameters
SCC-1 to SCC-21, 15 min
SCC-1 to SCC-21, 30 - 65 min
SCC-1 to SCC-21, 60 - 95 min
SCC-7, 95 min
LB = -0.0291JR + 1.091
R² = 0.8297
1.2
1
0.8
0.6
0.4
0.2
0
CV = -2.132
0 10 20 30 40 50 60 70
L-box blocking ratio (H2/H1)
J-ring, step of blocking (mm)
y = -35.468x + 734.67
R² = 0.2152
800
750
700
650
600
550
500
SCC-1 to SCC-20, 15 min
SCC-1 to SCC-20, 30 - 65 min
SCC-1 to SCC-20, 60 - 95 min
0 1 2 3 4
Slump flow spread (mm)
Rheological parameter, g
CV = -9.98
SCC-1 to SCC-20, 15 min
SCC-1 to SCC-20, 30 - 65 min
SCC-1 to SCC-20, 60 - 95 min CV = 1.0
y = 0.6142x + 0.8365
R² = 0.3028
12
10
8
6
4
2
0
0 2 4 6 8 10
Slump flow, t500 time (sec)
Rheological parameter, h

7. Empirical and Rheological parameters
SCC-1
SCC-2
SCC-3
SCC-4
SCC-5
SCC-6
SCC-7
SCC-8
SCC-9
SCC-10
SCC-11
SCC-12
SCC-13
SCC-14
SCC-15
SCC-16
SCC-17
SCC-19 SCC-18
SCC-20
SCC-21
LB = -0.0272JR + 1.0985
R² = 0.8995
1.2
1
0.8
0.6
0.4
0.2
0
CV = -1.043
0 5 10 15 20 25 30 35 40
L-box blocking ratio (H2/H1)
J-ring, step of blocking (mm)
SCC-1
SCC-21
SCC-15
SCC-2
SCC-3
SF = -43.024g + 730.89
SCC-4
SCC-5
SCC-19
SCC-6
SCC-7
SCC-8
SCC-10
SCC-9
SCC-11
SCC-12
SCC-13
SCC-16
SCC-17
SCC-18
SCC-20
SCC-14
R² = 0.7964
730
720
710
700
690
680
670
660
650
640
0.0 0.5 1.0 1.5 2.0 2.5
Slump-flow spread value (mm)
Rheological parameter, g
CV = -4.571
h = 1.6275t500 - 0.6795
R² = 0.8347
SCC-1 SCC-2
SCC-20 SCC-19
SCC-4
SCC-3
SCC-5
SCC-6
SCC-7
SCC-8
SCC-9
SCC-10
SCC-12
SCC-11
SCC-13
SCC-15
SCC-16
SCC-17
SCC-18
SCC-14
SCC-21
9
8
7
6
5
4
3
2
1
0
0 1 2 3 4 5 6
Rheological parameter, h
Slump-flow, t500 time (sec)
CV = 0.7172

8. Conclusions and Recommendations
 The rheological parameter g and h increase with an increase in SF content
 Correlation between rheology and workability
 Good correlation between L-box and J-ring (inversely related)
 Good correlation between inverted slump flow and g (inversely related)
 Good correlation between t500 time and h (positively related)
 Poor correlation between rheology and workability, 15 to 95 min.
 PFA and GGBS
 Reduction in g and an increase in h
 Retained workability

9. Recommendations
 Record idle pressures immediately after each test
 Weld steel ribs to inside of TWT bowl
 Modified Bingham model
 Fabricate a coaxial impeller arrangement for the TWT
 Torque calibration
 Expressing the parameters g and h into fundamental units
 Better control of the aggregates to evaluate the feasible use of SF
 Evaluate passing ability with J-ring