Research done at Berkeley � Mathematical model using double layer theory

� Neutron diffraction of reactive aggregates

� Soft X-ray microscopy of the expansive gels

� Characterization of the ASR gel � Repair strategies

Integration with various methods X-ray microscopy

ASR Gel

Dissolution in Na(OH) Neutron Diffraction AFM

ASR Gel ASR Gel in NaOH

ASR Gel in Ca(OH)2

Use of double layer models to predict the stresses and damaged

caused by the ASR gel

Double Layer Model

Silica

Inner-sphere complex: Ca

Diffuse ion

Outer-sphere complex: Na, K

Water

Fundamental Equations

+

________

+++++

++

+

+ +

+

++

+++

+

++

+

+

_

_ _

_

+

+

+

_

+

_

+

σo

σ σ σd+d d-= +

σo σd =+ 0

σo = Surface charge σd = Diffuse layer charge

Σ ( )

Local pressure gradient the two particles and the electrolyte solution,

∇P + ρ ∇Ψ = 0 where P is pressure, ρ is the net ion charge density, and ψ is the electric potential

ρ(Ψ) = Co F exp(- F Ψ / RT) - Co F exp(F Ψ / RT) Integrating the net ion charge density:

Computation of the stress

ΔP = Co R T [exp (-Ψo / ΨD) + exp (Ψo / ΨD) - 2]

where ΔP is the difference in pressure corresponding to an electric potential Ψo (relative to the bulk electrolyte solution as datum. The potential scaling factor ΨD = R T / F = 25.69 mV at 25 oC.

Need information of surface charge density of silica and silicates at high pH

+

________

+++++

++

+

+ +

+

++

+++

+

++

+

+

_

_ _

_

+

+

+

_

+

_

+

σo

σ σ σd+d d-= +

σo σd =+ 0

σo = Surface charge σd = Diffuse layer charge

Σ ( )

Experimental Research

� Surface charge density of silica at high values of pH and ionic strength

� Surface charge density of ASR gel at high values of pH and ionic strength

Phase I: Silica

0.1

1

10

100

5.0 6.0 7.0 8.0 9.0 10.0 11.0

silica gel NaClsilica gel KClopal NaClopal KClquartz NaClquartz KCl

-σH (

C.g

-1)

pH

Pressure: opal

0

2

4

6

8

10

12

5 6 7 8 9 10 11

pressure 0.7 KCL

pressure 0.7 NaCl

pressure 0.1 NaCl

Pres

sure

(MPa

)

pH

Phase II: ASR Gel

From the galleries

ASR Gel

Surface charge

0

0.2

0.4

0.6

0.8

1

9.50 10.0 10.5 11.0 11.5

-σH (

C.m

-2)

pH

An Important Result

0.01

0.1

1

6.00 7.00 8.00 9.00 10.0 11.0 12.0

-σH (

C.m

-2)

pH

Silica gel

0.01

0.1

1

6.00 7.00 8.00 9.00 10.0 11.0 12.0

-σH (

C.m

-2)

pH

ASR gel

Computation of stress

0

3

6

9

12

10 10.5 11 11.5

Pres

sure

(MPa

)

pH

References �  Monteiro, P. J. M., Kejin Wang, Garrison Sposito, Marcia C. dos Santos and W. Pacelli de

Andrade, “Influence of Mineral Admixtures on the Alkali-Aggregate Reaction,” CCR Journal, V27 N12: 1899, (1997).

�  M. Prezzi, Monteiro, P. J. M., and G. Sposito, “Alkali-Silica Reaction - Part 2: The Effect of Chemical Additives,” ACI Journal, JAN-FEB, V95 N1:3-10, (1998).

�  Monteiro, P.J.M., Wang, K., Sposito, G., dos Santos, M.C., and de Andrade, W. P., A Reply to Discussion of the Paper "Influence of Mineral Admixtures on the Alkali-Aggregate Reaction", CCR Journal, Vol. 28, No. 8, p.1195, 1998.

�  Rodrigues, F.A., and P.J.M. Monteiro, Sposito, G., "Surface Charge Density of Silica in Water-Acetone Mixtures," Journal of Colloid and Interface Science, Vol. 211, p. 408, 1999.

�  Rodrigues, F.A., Monteiro, P.J.M. and Sposito, G., "The Alkali-Aggregate Reaction: The Surface Charge Density of Silica and its Effect on the Expansive Pressure," CCR Journal, Vol. 29, p. 527, 1999.

References �  Rodrigues, F. A., P.J.M. Monteiro and G. Sposito, A Reply to Discussion of the Paper, “The alkali-

aggregate reaction: the surface charge density of silica and its effect on the expansive pressure” Cement and Concrete Research, V30(N3):503-504, (2000)

�  Rodrigues, F. A., P.J.M. Monteiro, and G. Sposito, “The alkali-silica reaction: the Effect of monovalent and bivalent cations on the surface charge of opal,” Cement and Concrete Research, V31, 1549-1552, 2001.

�  F. A. Rodrigues, , P. J. M. Monteiro, and G. Sposito A Reply to Discussion of the Paper “The Alkali-silica Reaction: The Effect Of Monovalent And Bivalent Cations On The Surface Charge Of Opal, Cement and Concrete Research, 933-934, 2003.

�  K. Shomglin, L. Turanli, H. -R. Wenk, P. J. M. Monteiro and G. Sposito The effects of potassium and rubidium hydroxide on the alkali–silica reaction, Cement and Concrete Research, Volume 33, Issue 11, November 2003, Pages 1825-1830

Phase III: Effect of admixtures

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

9.50 10.0 10.5 11.0 11.5

NaCl(NaCl+CaCl2)(NaCl+acetone)(NaCl+LiCl)

-σH (

C.m

-2)

pH

Microstructure: X-ray microscopy

ASR Gel

Dissolution in Na(OH)

Microstructure: X-ray microscopy

E. Kurtis, Monteiro, P. J. M., J. Brown, and W. Meyer-Ilse, “Imaging of ASR Gel by Soft X-ray Microscopy,” CCR journal, V28 N3:411-421, (1998).

In presence of saturated Ca(OH)2solution

E. Kurtis, Monteiro, P. J. M., J. Brown, and W. Meyer-Ilse, “Imaging of ASR Gel by Soft X-ray Microscopy,” CCR journal, V28 N3:411-421, (1998).

Effect of LiCl

0.7M NaOH + 0.1M LiCl solution scalebar = 1µm

Dissolution and the formation of a relatively small amount of repolymerized gel Lithium is known to stabilize colloids and to prevent gelling

Effect of LiCl

lithium may promote the aggregation of relatively larger (but still colloidal) silicate particles

Alkali-Aggregate Reaction

� Problematic siliceous aggregate are easy to identify but it is very challenging to characterize reactive silicate aggregates.

� The use of extinction angle is not reliable test

Scientific question:

How does amount of deformation in the aggregate affect its reactivity?

Our approach: Use neutron diffraction experiments

Materials

In an interesting location in the earthquake zone of Santa Rosa near Los Angeles, we collected granodiorite, mylonite, phylonite, and ultramylonite with the same chemistry but different amount of deformation.

� Prof. Rudy Wenk and I collecting the rocks

Ultramylonite

Granite Pyllonite

Deformation

Deformation

TEM: granite

15K

TEM: Mylonite

H.-R. Wenk, P.J.M. Monteiro and K. Shomglin, Relationship between aggregate microstructure and concrete expansion. A case study of deformed granitic rocks from the Santa Rosa Mylonite Zone, JOURNAL OF MATERIALS SCIENCE, Volume: 43, 1278-1285, 2008.

TEM: Phyllonite

20K

TEM: Formation of sub-grains

37K

TEM: Formation of sub-grains

59K

Determination of deformation in reactive aggregate

Texture Analysis – Quartz

Monteiro, P.J.M., K. Shomglin, H.R. Wenk and Nicole P. Hasparyk, “Effect of Aggregate Deformation on the Alkali-Silica Reaction,” ACI Materials Journal, V98 (N2): 179-183, Mar-Apr 2001.

Expansion

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 5 10 15 20 25 30 35

ultramylonite

granite

phyllonitemylonite

Exp

ansi

on (%

)

Time (day)

Note: all rocks had the same chemical composition

Deformation

Expansion tests

� The ASTM C 1260 expansion tests indicate that mortar expands increasingly when made with granite, mylonite, phyllonite, and ultramylonite respectively

Mortar Bar Expansion

0.00

0.20

0.40

0.60

1 1.5 2 2.5 3

14 days30 days

Exp

ansi

on (

%)

Multiples of Random Distribution Quartz 10(-1)2

Granodiorite

Mylonite

Phyllon ite

deformation

Texture Analysis – Biotite

Monteiro, P.J.M., K. Shomglin, H.R. Wenk and Nicole P. Hasparyk, “Effect of Aggregate Deformation on the Alkali-Silica Reaction,” ACI Materials Journal, V98 (N2): 179-183, Mar-Apr 2001.

Mortar Bar Expansion

0.00

0.20

0.40

0.60

0 5 10 15

14 days30 days

Exp

ansi

on (

%)

Multiples of Random Distribution Biotite 001

GranodioriteMylonite

Phyllon ite

Deformation

Effect of Grain Size

0.00

0.20

0.40

0.60

0.001 0.01 0.1 1 10

14-days30-days

Exp

ansi

on (%

)

Grain Size (mm)

Granodiorite

Mylonite

Phyllonite deformation

Conclusions

� There is a significant correlation between expansion and the development of foliation, and accompanying reduction in grain size.

�  The results suggest that the alkali-silica reaction depends on more factors than simply the crystallinity of quartz.

Conclusions

� Deformed granitic rocks provide a good system to quantify these parameters.

� Texture analysis of these rocks indicated that there is a quantitative relationship between the degree of deformation and reactivity

� STRUCTURE OF ALKALI SILICATE GEL BY TOTAL SCATTERING METHODS

Pair distribution function

( )dQ

QrQrQSQ

QfQfrG X

o

jiX

sin)(42

)()()(

0

23 ∫

∞

= πρπ

Where SX(Q) the structure factor and ρo=N/V is the atomic number density

Testing Methods

� High-energy x-ray diffraction measurements on beamline 1-ID at the Advanced Photon Source, Argonne National Laboratory.

� Incident beam energy of 100.0 keV. � Two-dimensional GE amorphous silicon area detector

The measured and background corrected x-ray intensity

0 5 10 15 20 25 300

100

200

300

10 15 20 25 30

15

20

25

N

orm

aliz

ed x

-ray

inte

nsity

Q (Å-1)C. Benmore and Monteiro P.J.M., The structure of alkali silicate gel by total scattering methods, Cement and Concrete Research, Volume 40, Issue 6, 2010, Pages 892-897.

Comparisons with MD (I) �  Thanks to Profs. Kirkpatrick and Kalinichev for

sharing their data. �  The persistence of a distorted kanemite-like

structure is in good agreement with the MD simulation.

�  The PDF measurements are consistent with MD predictions that it is energetically unfavourable for the water to penetrate the interlayer volume in significant quantity.

Comparisons with MD (II) � Our results show no distinct preferred

orientational correlations beyond ~10Å

X-ray differential distribution function D(r)

0 2 4 6 8-4

0

4

8

Si-O2

O-H inter.

K-O2

Si1-Si2

O1-O2, K-O1

O-H

bon

d

D(r

)

r (Angstrom)

Si-O bond

A local structural model of the amorphous alkali silicate gel

C. Benmore and Monteiro P.J.M., The structure of alkali silicate gel by total scattering methods, Cement and Concrete Research, Volume 40, Issue 6, 2010, Pages 892-897.

Where is the water?

� Due to the lack of long range ordering in this material we suggest that water molecules probably reside in pores surrounding these kanemite-like fragments as well as within the layers themselves.