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NANOSCALE MEASUREMENTS OF CEMENT HYDRATION DURING THE
INDUCTION PERIOD
Jeffrey S. SchweitzerDepartment of Physics
University of Connecticut
Storrs, Ct, USA
2nd International Symposium on Nanotechnology in Construction
Bilbao, Spain November 2005
Collaborators
• Richard A. Livingston, FHWA• Claus Rolfs, Hans-Werner Becker, Ruhr Universität
Bochum, Germany• Stefan Kubsky, Synchrotron SOLEIL, Saint-Aubin, Gif-
sur-Yvette CEDEX, France • Timothy Spillane, University of Connecticut• Marta Castellote Armero, Paloma G. de Viedma, IETcc
(CSIC), Madrid, Spain• Walairat Bumrongjaroen (University of Hawaii)• Supaluck Swatekititham (Chulalongkorn University)
Study of the Induction Period
• The details of the kinetics of the cement curing reactions are not known
• The reactions appear to be initiated at the grain surfaces
• Hydrogen plays a key role in the reaction process
• Studying the change in hydrogen concentration as a function of depth and time will provide insight into the reactions
0.1 1 10 100
HY
DR
AT
ION
PR
OD
UC
TS
PORTLAND CEMENT
FREE WATER
LOG TIME (days)
1.0
0.8
0.6
0.4
0.2
IND
UC
TIO
NP
ER
IOD
RE
AC
TIO
N P
RO
GR
ES
S
(Alp
ha)
0.80.60.40.20.0
W/C =0.4
after GLASSER et al. (1987)
FR
EE
WA
TE
R
IND
EX
0.0
0.2
0.4
0.6
0.8
1.0
MA
SS
PE
RC
EN
T
Nuclear Resonant Reaction Analysis (NRRA)
• Use of a narrow resonance (~ 1 keV) permits good spatial resolution
• Use of inverse kinematics (a 15N beam) provide large dE/dx, which improves spatial resolution
• A well isolated resonance provides the ability to have deep probing of the sample (~ 2-3 microns)
• All of these are provided by the 6.4 MeV
15N(p,)12C reaction
Resonance cross section
6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 710-1
100
101
102
103
104
105
Energy (MeV)
dd 1H(15N,)12C
Pellet Preparation
• Pure triclinic C3S powder
• Pressed into 13 mm dia. ring molds
• Fired at 1600 ºC to fuse upper surface
• Epoxied to stainless steel backing or with no backing
• Stored under nitrogen until used
Sample Preparation
• Saturated Ca(OH)2 Solution ( pH=12.5)
• Isothermal (10, 20 or 30 °C )
• N2 Purge of solution
• Specimens removed sequentially at
specified times
• Hydration stopped using methanol rinse
• Specimens dried to 10-6 Torr vacuum
Measurements
• Typical scan takes about one hour
• Chamber vacuum < 10-6
• Use of two beam charge states to cover complete energy range to 11 MeV
• Only background in gamma-ray spectrum is from cosmic rays
• Beam-line cold trap minimizes carbon buildup
Beam Energy Resolution
0
0.5
1
1.5
2
Cou
nts/c
harg
e
6.38 6.39 6.4 6.41 6.42 6.43 6.44 6.45 6.46
Beam Energy (MeV)
Slit Gain = 2.3
Slit Gain = 1.2
0 2 4 6 8 10 12
0
100
200
300
400
500
600
700
10°C, 4 Hours Beam Energy = 6.446 MeV
Co
un
ts
Gamma Ray Energy (MeV)
Time Progression
0.0 0.5 1.0 1.5 2.0 2.5
0
10
20
30
40
6 8 10 126 7 8 9 10 11 120.0
0.5
1.0
1.5
2.0
2.5
3.0
Depth (m)
Data, 30 oC, 0.25 Hours
Data, 30 oC, 0.50 Hours
H C
on
cen
trati
on
(m
mo
l/cm
3 )
Beam Energy (MeV)
Cts
/Ch
arg
e
6.4 6.5 6.6 6.7 6.8 6.9 7.00.0
0.5
1.0
1.5
2.0
2.5
3.0
Typical Scan at Early Times
0.0 0.5 1.0 1.5 2.0 2.5
0
10
20
30
40
6 8 10 126 7 8 9 10 11 120.0
0.5
1.0
1.5
2.0
2.5
3.0
Depth (m)
Data, 30 oC, 0.25 Hours
H C
on
cen
trati
on
(m
mo
l/cm3 )
Beam Energy (MeV)
Cts
/Ch
arg
e
6.4 6.5 6.6 6.7 6.8 6.9 7.00.0
0.5
1.0
1.5
2.0
2.5
3.0
C3S at 30 oC
0.0 0.5 1.0 1.5 2.0 2.5
0
10
20
30
40
6 8 10 126 7 8 9 10 11 120.0
0.5
1.0
1.5
2.0
2.5
3.0
Depth (m)
Data, 30 oC, 0.25 Hours
Data, 30 oC, 0.50 Hours
Data, 30 oC, 0.75 Hours H C
on
cen
trati
on
(m
mo
l/cm
3 )
Beam Energy (MeV)
Cts
/Ch
arg
e
6.4 6.5 6.6 6.7 6.8 6.9 7.00.0
0.5
1.0
1.5
2.0
2.5
3.0
Temperature Dependence of Induction Time
10
20
30
3.20 3.25 3.30 3.35 3.40 3.45 3.50 3.55 3.600.0
0.5
1.0
1.5
2.0
2.5
3.0
t = CeEa/RT
C = 8.1x10-13 hrE
a= 69± 4 kJ/mol
R = 0.998
ARRHENIUS PLOT OF INDUCTION TIMES
LN
(IN
DU
CT
ION
TIM
E),
Hrs
RECIPROCAL TEMPERATURE, 1000/T (K-1)
Data Linear Fit
0.0 0.5 1.0 1.5 2.0 2.5
0
10
20
30
40
6 8 10 126 7 8 9 10 11 120.0
0.5
1.0
1.5
2.0
2.5
3.0
Depth (m)
Data, 30 oC, 0.75 Hours Gaussian Peak Constant Diffusion Constant Fit Baseline
H C
on
ce
ntr
ati
on
(m
mo
l/c
m3 )
Beam Energy (MeV)
Cts
/Ch
arg
e
6.4 6.5 6.6 6.7 6.8 6.9 7.00.0
0.5
1.0
1.5
2.0
2.5
3.0
D=1.5 X10-10 cm2/s
Hydrogen Profile Pre-breakdown
0.0 0.5 1.0 1.5 2.0 2.5
0
10
20
30
40
6 8 10 126 7 8 9 10 11 120.0
0.5
1.0
1.5
2.0
2.5
3.0
Depth (m)
Data, 30 oC, 0.75 Hours Gaussian Peak Constant Diffusion Constant Fit Baseline
H C
on
cen
trati
on
(m
mo
l/cm
3 )
Beam Energy (MeV)
Cts
/Ch
arg
e
6.4 6.5 6.6 6.7 6.8 6.9 7.00.0
0.5
1.0
1.5
2.0
2.5
3.0
D=1.5 X10-10 cm2/s
Hydrogen Profile Post-breakdown
0.0
0.5
1.0
1.5
2.0
2.5
3.00.0 0.5 1.0 1.5 2.0 2.5
6 7 8 9 10 11 120
10
20
30
40
Data, 30 oC, 2 Hours
Constant Diffusion Constant Fit Baseline
Depth (m)
D=8.4X10-12
cm2/s
Beam Energy (MeV)
6.4 6.5 6.6 6.7 6.8 6.9 7.00.0
0.5
1.0
1.5
2.0
2.5
3.0
Cts
/Ch
arg
e
H C
on
ce
ntr
ati
on
(m
mo
l/c
m3 )
0.0
0.5
1.0
1.5
2.0
2.5
3.00.0 0.5 1.0 1.5 2.0 2.5
6 7 8 9 10 11 120
10
20
30
40
Data, 30 oC, 2 Hours Constant Diffusion Constant Fit Baseline
Depth (m)
D=8.4X10-12 cm2/s
Beam Energy (MeV)
6.4 6.5 6.6 6.7 6.8 6.9 7.00.0
0.5
1.0
1.5
2.0
2.5
3.0
Cts
/Ch
arg
e
H C
on
cen
trati
on
(m
mo
l/cm
3 )
H Concentration with Retarder and Accelerator
6 7 8 9 10 11 120
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
H, G
am
ma
Co
un
ts
10 mmol/L Sucrose, 24 hrs I M Calcium Chloride, 1.5 hrs
Beam Energy, MeV
Comparison of Profiles
6 7 8 9 10 110.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
6 7 8 9 10 110.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
6.0 7.0 8.0 9.0 10.0 11.00.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
C3S Accelerated (1.0 hr)
MeV
Cts
/Charg
e C
ts/C
harg
e C
ts/C
harg
e
C3S Retarded (1.25 hr)
C3S Normal (1.25 hr)
Comparison with Belite
6 7 8 9 10 110.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
6 7 8 9 10 110.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
6.0 7.0 8.0 9.0 10.0 11.00.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
C3S Accelerated (1.0 hr)
MeV
Cts
/Charge
Cts
/Charge
Cts
/Charge
Belite (1.25 hr)
C3S Normal (1.25 hr)
Time Dependence of Belite Hydration Profiles
6.0 6.5 7.0 7.5 8.0 8.5 9.0
0.0
0.5
1.0
1.5
2.0
2.5
3.012.5 hr
11.25 hr10 hr8.75 hr
7.5 hr6.25 hr
5 hr3.75 hr
2.5 hr
1.25 hrUnhydrated, Rinsed
Unhydrated
Belite
Cts
/Ch
arg
e
MeV
Highly Accelerated
6 7 8 9 10 11
-500
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
6500
Cts
/Cha
rge
MeV
6 Hr 5 Hr 4 Hr 3 Hr 2.5 Hr 2 Hr 1.5 Hr 0.75 Hr
C3S, 30 C, 1 M CaCl
2
6 7 8 9 10 11-500
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
6500
Cts
/Charg
e
MeV
6 Hr 5 Hr 4 Hr 3 Hr 2.5 Hr 2 Hr 1.5 Hr 0.75 Hr
C3S, 30 C, 1 M CaCl
2
Lightly Accelerated
6 7 8 9 10 11-500
0
500
1000
1500
2000
2500
3000
3500
4000
4500
Y A
xis
Title
X Axis Title
3.5 Hr 3.0 Hr 2.5 Hr 2.0 Hr 1.5 Hr 1.0 Hr 0.5 Hr
C3S, 30 C, 20mmol/L CaCL
2
Figure 5: Hydration profiles for C3A at various times. The 0 minute sample was nothydrated, but was treated with methanol and then stored in the vacuum with the others.
6.50 6.75 7.00 7.25 7.500
2
4
6
8
10
Th
ou
san
d C
ou
nts
Beam Energy, MeV
Min 0 5 10 20 30 40
C3A Hydration, 10ºC
Ternary Diagram of Glass CompositionTernary Diagram of Glass Composition
Na2O+K2O0 10 20 30 40 50 60 70 80 90 100
SiO2+Al2O3+Fe2O3
0
10
20
30
40
50
60
70
80
90
100
CaO
0
10
20
30
40
50
60
70
80
90
100
1.28
2.06 1.86 1.65
0.79
0.290.330.45
3.0 1.0 0.33
Glass Hydration ProcedureGlass Hydration Procedure
• Saturated Li(OH)2 Solution ( pH=12)
• N2 purge to prevent carbonation• Specimens removed at 72 hours• Hydration stopped using methanol rinse• Specimens dried in 10-6 Torr vacuum
NRRA Results of FF SeriesNRRA Results of FF Series
6.5 7.0 7.5 8.0 8.50
2000
4000
6000
8000
10000
12000
14000
Synthetic FF Fly Ash Glass Hydration, 24ºC 72 hrs, pH 12 LiOH Solution
C
ou
nts
Beam Energy, MeV
F1 F2 F3
NRRA Results of Low-Ca CFNRRA Results of Low-Ca CF
6.5 7.0 7.5 8.0 8.50
1000
2000
3000
4000
5000
6000
7000
8000
C
ou
nts
Beam Energy, MeV
C2 C3 C4
Synthetic CF Fly Ash Glass Hydration, 24ºC 72 hrs, pH 12 LiOH Solution
NRRA Results of High-Ca CFNRRA Results of High-Ca CF
6.5 7.0 7.5 8.0 8.50
1000
2000
3000
4000
5000
6000
7000
8000
C
ou
nts
Beam Energy, MeV
C1 C5
Synthetic CF Fly Ash Glass Hydration, 24ºC 72 hrs, pH 12 LiOH Solution
Future Research
• Effects of Al2O3, Fe2O3 in alite
• Effect of time-varying solution chemistry
• Effects of accelerators & retarders
• Relationship between surface layers and time of initial set
• Effects of cement storage conditions, i.e. “dusting”
Conclusions• NRRA is a powerful technique for understanding cement hydration
and it can determine induction period with a precision of 4 minutes or 2%
• Spatial resolution on the order of 2-3 nm can be achieved
• A surface layer is formed during the induction period for C3S but not for C2S
• Induction period determined by mechanical breakdown of surface layer ~ 10-20 nm thick.
• Hydration involves concentration-dependent diffusion process
• Further work is needed to determine the affects of accelerators and especially of retarders, and to understand hydration of other cement components
Recommended