effect of addition of superabsorbent polymers (sap) … of addition of superabsorbent polymers (sap)...
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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