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

Resonant Reaction Depth Profiling

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

Typical Experimental Plan

Temperature Number of Pellets Time SpanoCHrs

10 10 21

20 4 5.5

30 10 2.5

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 )

Reaction zones in hydrating C3S during the induction period.

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