Effect of addition of superabsorbent polymers

(SAP) on rheological properties of fresh cement-

based mortars

M.Sc. Egor Secrieru, Prof. Dr.-Ing. Viktor Mechtcherine

Regensburg, 06.03.2013

Fakultät Bauingenieurwesen, Institut für Baustoffe, Prof. Dr.-Ing. Viktor Mechtcherine

22. Kolloquium und Workshop, Rheologische Messungen an

mineralischen Baustoffen

TU Dresden, Institut für Baustoffe, M.Sc. Egor Secrieru 2/15

Mostly cross-linked polyelectrolytes

Water absorption:

- max. water absorption ca. 1500 g/g

- commercial SAP ca. 50 – 300 g/g

- in high-ionic solutions mostly < 30 g/g

SAP before water absorption SAP after water absorption Raw SAP (particle ca. 200 µm)

Superabsorbent Polymers as internal curing-agent

Superabsorbent polymers (SAP)

TU Dresden, Institut für Baustoffe, M.Sc. Egor Secrieru

-2

0

2

4

6

8

0 7 14 21 28

Corrugated

tubes

Instrumented

ring test

Free and restrained autogenous

shrinkage (AS) examination

Free AS of UHPC

Residual tensile stresses of UHPC

Tensile

str

ess [

MP

a]

Time [d]

Additon of SAP and

extra IC water mitigates

susceptibility to cracking

related to AS

Str

ain

x 1

0³

[µm

/m]

Time after final set [d]

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0 7 14 21 28

F-S.4.07

F-R F.07-1 (less SP)

F-R

F.07-2

F-S.4.07

Tensile

str

ess [

MP

a]

S

train

x 1

0³

[µm

/m]

Internal Curing of HPC

3/15

TU Dresden, Institut für Baustoffe, M.Sc. Egor Secrieru 4/15

REF FC1.2 FC1.2-S FC1.2-S-W

0

250

500

750

1000

1250

1500

0 7 14 21 28

Freeze-thaw cycles [-]

Ma

teri

al lo

ss

[g/m

²] REF

FC1.2

FC1.2-S

FC1.2-S-W

FC1.2-S-W

0

1

2

3

4

5

6

0 1 2 3 4 5

Strain [%]

Str

ess [M

Pa]

Enhancing Frost Resistance and More

SHCC with SAP

TU Dresden, Institut für Baustoffe, M.Sc. Egor Secrieru

Coarse Coarse

Two chemically distinct SAPs: SAP-B and SAP-D

Fine

SAP-B SAP-DC SAP-DF

5/15

Superabsorbent polymers

TU Dresden, Institut für Baustoffe, M.Sc. Egor Secrieru

SAP absorption behaviour

in a syntehtic pore fluid

0

10

20

30

40

50

0 15 30 45 60 75 90

Absorp

tion [g/g

]

Time [min]

Particle size distribuition of

different SAP samples

Superabsorbent polymers

0

2

4

6

8

10

0 500 1000 1500 2000D

iffe

rential V

olu

me [%

]

Particle Diameter [μm]

DC

B

DF

6/15

TU Dresden, Institut für Baustoffe, M.Sc. Egor Secrieru

0

100

200

300

400

500

0 2 4 6 8 10

Shea

r str

ess [

Pa

] Shear rate [1/s]

τ0

μ

Continuous shear rate test

Unit cell

Rotor

HAAKE MARS II rheometer

Rheological equipment

7/15

TU Dresden, Institut für Baustoffe, M.Sc. Egor Secrieru

Measuring profile for the rheometer

Testing procedure

8/15

Segment Type Time [s] Further settings

0 Lift 5 Lift control: rotor to the measurement position

1 Osc-Time 30 Oscillation-time test, τ = 0 Pa, f = 1.0 Hz

2 Osc-As 150 Oscillation amplitude test, τ = 1÷400 Pa, f = 1.0 Hz, 40 steps

3 CS-RT 30 Controlled shear stress recovery test, τ = 0 Pa, 30 steps

4 CR-RS 40

5 CR-Time 30

6 CR-RS 40

TU Dresden, Institut für Baustoffe, M.Sc. Egor Secrieru

Mortar mixes

9/15

Group A

High SP content

Group B

High SP content

Silica fume

A_RefMix_0.30 for 1 m3 [kg]

Cement CEM I 42.5 R 776.0

Water 232.7

Aggregate 0/2 1300.0

SP Glenium 51 1.4 wt-% bwoc 10.9

B_RefMix_0.30 for 1 m3 [kg]

Cement CEM I 42.5 690.0

Silica fume Elkem 971 10 % bwoc 69.0

Water 227.5

Aggregate 0/2 1300.0

SP Glenium 51 2.0 wt-% bwoc 13.8

TU Dresden, Institut für Baustoffe, M.Sc. Egor Secrieru 10/15

Preliminary tests with SAP-DC

Yield stress Plastic viscosity

0

15

30

45

60

75

90

0 20 40 60 80 100

Pla

stic V

iscosity [P

a·s

]

Time [min]

0

5

10

15

20

25

30

0 20 40 60 80 100Y

ield

Str

ess [P

a]

Time [min]

A_0.30DC_0.35

A_RefMix_0.30

A_0.20DC_0.35

A_0.15DC_0.35

TU Dresden, Institut für Baustoffe, M.Sc. Egor Secrieru 11/15

0

10

20

30

40

0 20 40 60 80 100

Pla

stic V

iscosity [P

a·s

]

Time [min]

A_0.50B_0.35

A_0.40B_0.35

A_RefMix_0.30

A_0.30B_0.350

20

40

60

80

100

120

0 20 40 60 80 100Y

ield

Str

ess [P

a]

Time [min]

Preliminary tests with SAP-B

Yield stress Plastic viscosity

TU Dresden, Institut für Baustoffe, M.Sc. Egor Secrieru

Effect on plastic viscosity

12/15

Group A mortars

Changes in ref. to mix A: B: SP↑+silica fume

0

10

20

30

40

50

0 20 40 60 80 100

Pla

stic V

iscosity [P

a·s

]

Time [min]

A_0.20DC_0.35

A_0.20DF_0.35

A_RefMix_0.30

A_0.40B_0.35

0

10

20

30

40

50

0 20 40 60 80 100P

lastic V

iscosity [P

a·s

]

Time [min]

B_0.20DF_0.35

B_0.20DC_0.35

B_RefMix_0.30

B_0.40B_0.35

Group B mortars

TU Dresden, Institut für Baustoffe, M.Sc. Egor Secrieru 13/15

0

10

20

30

40

0 20 40 60 80 100Y

ield

Str

ess [P

a]

Time [min]

B_0.20DF_0.35

B_RefMix_0.30

B_0.40B_0.35

B_0.20DC_0.35

0

10

20

30

40

0 20 40 60 80 100

Yie

ld S

tress [P

a]

Time [min]

A_0.20DF_0.35

A_RefMix_0.30

A_0.20DC_0.35

A_0.40B_0.35

Effect on yield stress

Changes in ref. to mix A: B: SP↑+silica fume

Group A mortars Group B mortars

TU Dresden, Institut für Baustoffe, M.Sc. Egor Secrieru

Prominent rheological effect of SAP

Distinct absorption-desorption behaviour of SAP-D and SAP-B

Influence of grain size distribution

Summary

14/15

TU Dresden, Institut für Baustoffe, M.Sc. Egor Secrieru

Acknowledgements

15/15