The Rheological Characteristics of SFRSCC with PFA and GGBS

CONCRETE RHEOLOGY

CONCRETE WORKABILITY

CORRELATION

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

0 1 2 3 4 5 6 7 80

2

4

6

8

10

12

Speed (rev/s)

Tor

que

(N/m

)

Slope = h

T = To + ANb

g

Linear approximation of Hershel-Bulkley model

0 1 2 3 4 5 6 7 80

2

4

6

8

10

12

Shear strain rate, γ

Shea

r str

ess,

τ

Slope = µ

τ = τo + Kγn

τo

Linear approximation of Hershel-Bulkley model

Mix Design and Testing Sequence

  REF REF  REF

ComponentSeries 1 (kg/m3)

Series 2 (kg/m3)

Series 3 (kg/m3)

CEM II/A-L 580 406 290Limestone filler 20 20 20GGBS - - 290PFA - 174 -Fine aggregate 1020 1020 1020Coarse aggregate 630 630 630Superplasticiser (Glenium 27) 12.5 12.5 12.5Stabiliser (RheoMatrix 100) 78 78 78Water 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 o5 (kg/m3) o o o10 (kg/m3) o o o15 (kg/m3) o o o20 (kg/m3) o o o25 (kg/m3) o o o30 (kg/m3) o o o     

       

SequenceRegime-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 TWT2 Slump flow Slump flow Slump flow3 L-box L-box L-box4 J-ring J-ring J-ring

Hershel-Bulkley Curve Fitting

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

0

1

2

3

4

5

6R² = 0R² = 0R² = 0

SCC-1, 15 min

Polynomial (SCC-1, 15 min)

SCC-1, 45 min

Polynomial (SCC-1, 45 min)

SCC-1, 75 min

Polynomial (SCC-1, 75 min)

Hershel-Bulkley, 15 min

Hershel-Bulkley, 45 min

Hershel-Bulkley, 75 min

Speed (rev/s)

Tor

que

(N/m

)

Effect of PFA and GGBS on Rheology and workability

0 5 10 15 20 25 300

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

SFRSCC

SFRSCC with PFA

SFRSCC with GGBS

Steel fibre content (kg/m3)

Rheolo

gic

al para

mete

r, g

0 5 10 15 20 25 300

1

2

3

4

5

6

7

SFRSCC

SFRSCC with PFA

SFRSCC with GGBS

Steel fibre content (kg/m3)

Rheolo

gic

al para

mete

r, h

0 5 10 15 20 25 300

10

20

30

40

50

60

70

80

SFRSCCSFRSCC with 30% PFASFRSCC with 50% GGBS

Steel fibre content (kg/m3)

7-D

ay s

trength

(N

/mm

)

STD: 1.3

STD: 1.08STD: 1.5

Empirical and Rheological Parameters

0 10 20 30 40 50 60 700

0.2

0.4

0.6

0.8

1

1.2

f(x) = − 0.0290657251388758 x + 1.09101341644886R² = 0.829717455591301

SCC-1 to SCC-21, 15 min

SCC-1 to SCC-21, 30 - 65 min

J-ring, step of blocking (mm)

L-b

ox b

lock

ing

ratio

(H

2/H

1)

CV = -2.132

0 0.5 1 1.5 2 2.5 3 3.5500

550

600

650

700

750

800

f(x) = − 35.4682188203232 x + 734.669158742188R² = 0.21517400976868

SCC-1 to SCC-20, 15 min

Linear (SCC-1 to SCC-20, 15 min)

Rheological parameter, g

Slu

mp

flow

spr

ead

(mm

)

CV = -9.98

2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 70

2

4

6

8

10

12

f(x) = 0.614155144502876 x + 0.836509601156264R² = 0.30281072967086

SCC-1 to SCC-20, 15 min

Linear (SCC-1 to SCC-20, 15 min)

Rheological parameter, h

Slu

mp

flow

, t50

0 tim

e (s

ec)

CV = 1.0

Empirical and Rheological parameters

0 5 10 15 20 25 30 350

0.2

0.4

0.6

0.8

1

1.2

f(x) = − 0.0272018128551079 x + 1.0984591157247R² = 0.899463415391305

J-ring, step of blocking (mm)

L-b

ox b

lock

ing

ratio

(H

2/H

1)

CV = -1.043

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0600

620

640

660

680

700

720

740

SCC-14

SCC-21

f(x) = − 43.0242709698268 x + 730.885232433187R² = 0.796421966228956

Rheological parameter, g

Slu

mp-

flow

spr

ead

valu

e (m

m)

CV = -4.571

1.5 2 2.5 3 3.5 4 4.50

1

2

3

4

5

6

7

SCC-14

SCC-21f(x) = 1.62751162621118 x − 0.679462981188106R² = 0.834719873080687

Slump-flow, t500 time (sec)R

heol

ogic

al p

aram

eter

, h

CV = 0.7172

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

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