QUANTIFICATION OF PORE QUANTIFICATION OF PORE QUANTIFICATION OF - - PowerPoint PPT Presentation

▶
quantification of pore quantification of pore
SMART_READER_LITE
LIVE PREVIEW

QUANTIFICATION OF PORE QUANTIFICATION OF PORE QUANTIFICATION OF - - PowerPoint PPT Presentation

Aug 18, 2023 314 likes •712 views

QUANTIFICATION OF PORE QUANTIFICATION OF PORE QUANTIFICATION OF PORE STRUCTURE CHARACTERISTICS STRUCTURE CHARACTERISTICS STRUCTURE CHARACTERISTICS FOR DETERIORATED MORTAR FOR DETERIORATED MORTAR FOR DETERIORATED MORTAR DUE TO CALCIUM

slide-1
SLIDE 1

QUANTIFICATION OF PORE STRUCTURE CHARACTERISTICS FOR DETERIORATED MORTAR DUE TO CALCIUM LEACHING BY SYNCHROTRON MICROTOMOGRAPHY QUANTIFICATION OF PORE QUANTIFICATION OF PORE STRUCTURE CHARACTERISTICS STRUCTURE CHARACTERISTICS FOR DETERIORATED MORTAR FOR DETERIORATED MORTAR DUE TO CALCIUM LEACHING BY DUE TO CALCIUM LEACHING BY SYNCHROTRON SYNCHROTRON MICROTOMOGRAPHY MICROTOMOGRAPHY

Takafumi SUGIYAMA (Hokkaido Univ.) Michael A. B. PROMENTILLA (Hokkaido Univ.) Takashi HITOMI (Obayashi Co. ) Nobufumi TAKEDA (Obayashi Co. )

slide-2
SLIDE 2

Calcium leaching Calcium leaching Degrading mechanical and Degrading mechanical and transport properties transport properties Change of pore structure Change of pore structure characteristics characteristics

Sand and Clay

Concret e

Rock

Cement it ious barrier

Bent nit e

Wast e

Material Degradation in Long Term Service Material Degradation in Long Material Degradation in Long Term Service Term Service

Radioactive Waste Repository Radioactive Waste Repository

slide-3
SLIDE 3

Development for calculation model of ion Development for calculation model of ion transport in hydrated cement system transport in hydrated cement system ( (SiTraM SiTraM in 2003) in 2003)

x C D J

j n 1 j ij i

s

∂ ∂ − = ∑

=

Ion-Ion Interaction in pore solution

Cl- OH- Na+ K+ Ca2+

Cs C0 Cb Cf

Ion-Solid Interactions

Ca2+ leaching Cl- binding

∆ΦL ∆ΦR

Membrane potential

  • + +
  • + +
  • + +
  • K+

K+ Na+ Na+ Ca2+ Cl- Cl- Cl-

Electrical double layer

Ca2+

ε τ δ Pore structure characteristic

Steady-state migration test

slide-4
SLIDE 4

Significance of pore structure characteristics for material properties Significance of pore structure Significance of pore structure characteristics for material characteristics for material properties properties

Strength Performance of Cement-based Materials Transport Properties of Cement-based Materials Pore Structure Characteristics 3D Micro-geometry Porosity, Diffusion Tortuosity

slide-5
SLIDE 5

Pore Structure Characteristics of Cement-based Materials estimated from 3D Micro-geometry using Synchrotron Microtomography

Methodology: Synchrotron microtomography

Random Walk Simulation

Application to deteriorated mortars and cement

pastes

Accelerated electrical tests for calcium leaching

slide-6
SLIDE 6

Synchrotron Microtomography Synchrotron Synchrotron Microtomography Microtomography

Bentz et al 2000, Helfen et al. 2005, Lu et al. 2006, Burlion et al. 2006, Koster 2006, Gallucci et al. 2007 SPring-8 (Japan)

  • Same principle as medical CT scan

– Creates X-ray image of ‘slice’ through object that can make 3D volume – But higher-energy, more focused Synchrotron-based X- rays (higher spatial resolution) – X-ray source is tunable, X-ray radiation is monochromatic, and X-ray beam is flat

  • Applications

Geology, Anthropology, Biology, Medicine, Engineering

・Advantage and Disadvantage

6/38

slide-7
SLIDE 7

X-ray imaging of specimen 3D reconstruction of image 3D Image processing Extraction of 3D pore space Visualization and quantification of porosity Quantification of tortuosity based on random walk simulation (RWS) Pore segmentation Pore cluster multiple labeling Mathematica program (Nakashima et al.2007) SLICE (Nakano et al., 2007) SPring-8 Pixel size = 0.5 micron 7/38

slide-8
SLIDE 8

X‐ray Scanning of Specimen

１０００μm BL47XU X-Ray source Rotating Stage Specimen

Beam energy: 15 kev 2000x1300 px CCD 1500 projections (1800 rotation)

CCD 8/38

slide-9
SLIDE 9

SLICE 400

Mortar before deterioration Mortar before deterioration

Water to cement ratio:0.5 Sand to cement ratio :2.0 Curing periods: 238days

100 µm

slide-10
SLIDE 10

Extraction of 3D image (VOI) Extraction of 3D image (VOI) Extraction of 3D image (VOI)

300 x 300 pixels in 2D 300 x 300 x 300 pixels (VOI) 150 µm Based on REV (Representative Elementary Volume) analysis

slide-11
SLIDE 11

Accelerated Electrical Method Accelerated Electrical Method Accelerated Electrical Method

Direct current voltage Anode Cathode

Cement paste

Ca

２ ＋

Ca

２ ＋

Ca

２ ＋

Ca

２ ＋

Electrode (Pt) Electrode (SUS) Ion-change water Ion-change water

Schematic diagram for accelerated electrical test Acceleration test underway using Acrylic cell

11/38

slide-12
SLIDE 12

Distribution of CaO/SiO2 ratio in cement hydrate (obtained by EPMA) Distribution of Ca Distribution of CaO O/Si /SiO O2

2 ratio in

ratio in cement hydrate (obtained by cement hydrate (obtained by EPMA) EPMA) According to Saito et al. ACI Materials J. 1999

Acceleration Acceleration test test

Inner side Inner side Surface Surface

Diffusion Diffusion test test

After 2,000days After 2,000days

Inner side Inner side Cathode side Cathode side

After 2months under 5 V/cm After 2months under 5 V/cm

2mm 2mm 8mm 8mm 6mm 6mm

slide-13
SLIDE 13

Specimens under investigation Specimens under investigation Specimens under investigation

W/C Cement Sand Chemical admixture Mortar 0.5 OPC Sieved under 210µm (S/C:2.0) Super-plasticizer Cement paste 0.5 OPC Non Viscosity agent (cellulose-ether type)

OPC: Ordinary Portland Cement JIS R5210

Non-deteriorated mortar: 30 weeks in curing Deteriorated mortar: 20weeks in curing followed by acceleration test for 13weeks Cement paste: 20weeks in curing followed by acceleration test for13weeks

13/38

slide-14
SLIDE 14

SLICE ５００

Deteriorated Mortar Deteriorated Mortar Non deteriorated Mortar Non deteriorated Mortar

150 µm SLICE ５００

slide-15
SLIDE 15

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 240 255

GSV segmented porosity

0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.010

  • norm. frequency

Porosity-Threshold dependency curve of VOI

Threshold value for segmentation

At this transition point, the segmented porosity started to increase rapidly wherein the boundary between pore and the solid matrix is most likely to be segmented as pore space.

Deteriorated Mortar Deteriorated Mortar

15/38

slide-16
SLIDE 16

Deteriorated Mortar (D.M.) Deteriorated Mortar (D.M.)

16/38

slide-17
SLIDE 17

(a) Grayscale image (b) Segmented image

(White for Solid, Black for Pore) 150μm

  • D. M.
  • D. M.

Non Non

  • D. M.
  • D. M.
slide-18
SLIDE 18

Segmented porosity, εt Connectivity

γ

Effective porosity, εe 0.39 0.98 0.38 0.04 0.51 0.02

Quantification of porosity Quantification of porosity Quantification of porosity

εt εt x γ εe

Total pore voxels Total voxels

= =

  • No. of voxels of the largest percolating pore

γ

=

18/38

Total pore voxels

slide-19
SLIDE 19

Pore Cluster Multiple Labeling

Hoshen-Kopelman Algorithm

Binary Image Matrix (Pore GSV = 0) Labeled pore clusters

255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255

2 2 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 5 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 1 4 1

19/38

slide-20
SLIDE 20

Diffusion Tortuosity and Random Walk

( ) ( ) ( )

2 2

2 r r t r dD t t ′ ′ ⎡ ⎤ = − = ⎣ ⎦

Time-dependent diffusion coefficient

  • f random Brownian motion of molecules

To probe the geometry of porous media

For 3D random walk (d =3)

MSD

) ( t D D = τ

Diffusion Tortuosity

Free space (porosity = 100 %) Pore space (restricted diffusion)

t r D

2

6 1 =

dt r d t D

2

6 1 ) ( =

20/38

slide-21
SLIDE 21

Pore structural model: Capillary model Pore space : Diffusion tortuosity

Le Tortuosity L =

L Le

  • D

Tortuosity D∞ =

MSD time,t Mean square displacement vs time

Unrestricted diffusion Restricted diffusion

( )

D t D =

( )

D t D <

closed system

  • pen

system

Unidimensional: percolating in the x-direction

1

f

τ ≥

2 f

Le L τ ⎛ ⎞ = ⎜ ⎟ ⎝ ⎠

21/38

slide-22
SLIDE 22

Time-Dependent Diffusion Tortuosity

( )

1 D t D τ =

1

Free space Closed pore Open pore

t: diffusion time

22/38

slide-23
SLIDE 23
  • 10

10 20 X

  • 10

10 20 Y

  • 10

10 20 Z

  • 10

10 X 10 Y

  • 10

10 20 X

  • 10

10 20 Y

  • 10

10 20 Z

  • 10

10 X 10 Y

  • 10

10 20 X

  • 10

10 20 Y

  • 10

10 20 Z

  • 10

10 X 10 Y

00 . 1 = τ

( )

2

40 . 2 = τ

( )

2

78 . 2 = τ

1 Le L ⎛ ⎞ = ⎜ ⎟ ⎝ ⎠ 2.40 Le L ⎛ ⎞ = ⎜ ⎟ ⎝ ⎠ ? Le L ⎛ ⎞ = ⎜ ⎟ ⎝ ⎠

23/38

slide-24
SLIDE 24

Deteriorated Mortar Deteriorated Mortar

A sample trajectory of a random walker in 3D pore space of DM

  • 200

200 400 X

  • 200

200 400 Y

  • 200

200 400 Z

  • 200

200 400 X

  • 200

200 400 Y

Percolating pore= 0.38 (98% of Porosity)

Diffusion tortuosity: 4

2 million time steps 2 million time steps 50,000 walkers 50,000 walkers 24/38

slide-25
SLIDE 25

Cement paste: Profiles for Ca and Si Cement paste: Profiles for Ca and Cement paste: Profiles for Ca and Si Si

2 10 2 2

unit：mm

2 2

Ca

２ ＋

Ca

２ ＋

de1 de2 de3

50

Ca

２ ＋

Ca

２ ＋

Sliced samples for X ray CT

5 10 15 20 25 30 1 2 3 4 5 6 7 8 9 10 D i st ance f rom cat hode ( m m )

Si O 2%

10 20 30 40 50 1 2 3 4 5 6 7 8 9 10 Di stance f rom cathode ( m m )

C aO %

25/38

slide-26
SLIDE 26

de1

SLI CE300

150 µm

slide-27
SLIDE 27

de2

SLI CE300

150 µm

slide-28
SLIDE 28

de3

SLI CE300

150 µm

slide-29
SLIDE 29

Reference OPC paste

SLI CE300

150 µm

slide-30
SLIDE 30

de1 de2 de3 OPC

Segmented pores

slide-31
SLIDE 31

RWS de1

  • 200

200 400 600

  • 200

200 400 600 X Y

  • 200

200 400 600

  • 200

200 400 600 X Y

  • 200

200 400 600

  • 200

200 400 600 Z X

  • 200

200 400 600 X

  • 200

200 400 600 Y

  • 200

200 400 600 Z

  • 200

200 400 X

  • 200

200 400 Y

2 22 10

unit：mm

2 2

Ca

２ ＋

Ca

２ ＋

de1 de2 de3

50

Ca

２ ＋

Ca

２ ＋

2 million time steps 2 million time steps 50,000 walkers 50,000 walkers 31/38

slide-32
SLIDE 32

RWS de2

  • 200

200 400 600

  • 200

200 400 600 X Y

  • 200

200 400 600

  • 200

200 400 600 Y Z

  • 200

200 400 600

  • 200

200 400 600 Z X

  • 200

200 400 600 X

  • 200

200 400 600 Y

  • 200

200 400 600 Z

  • 200

200 400 X

  • 200

200 400 Y

2 22

unit：mm

2 2

Ca

２ ＋

Ca

２ ＋

de1 de2 de3

50

Ca

２ ＋

Ca

２ ＋

2 million time steps 2 million time steps 50,000 walkers 50,000 walkers 32/38

slide-33
SLIDE 33

RWS de3

  • 200

200 400 600

  • 200

200 400 600 X Y

  • 200

200 400 600

  • 200

200 400 600 X Y

  • 200

200 400 600

  • 200

200 400 600 Z X

2 million time steps 2 million time steps 50,000 walkers 50,000 walkers

  • 200

200 400 600 X

  • 200

200 400 600 Y

  • 200

200 400 600 Z

  • 200

200 400 X

  • 200

200 400 Y

2 22

unit：mm

2 2

Ca

２ ＋

Ca

２ ＋

de1 de2 de3

50

Ca

２ ＋

Ca

２ ＋

33/38

slide-34
SLIDE 34

Cathode

1 2 3 4 5 6 1 2 3 4 5 6 7 8 9 10

CaO/SiO2

0.33 0.31 7 0.21 0.17 11 0.14 0.09 41

de1 de2 de3 Anode

εt εe τ

slide-35
SLIDE 35

Segmented porosity, εt Effective porosity, εe Diffusion tortuosity, τ 0.33 0.31 7 0.21 0.17 11 0.14 0.09 41 0.09 0.02 n/a

slide-36
SLIDE 36

Conclusions 1/2 Conclusions 1/2 Conclusions 1/2

(1) The Synchrotron Microtomography technique can provide better understanding of the microstructure change in deteriorated mortar and cement paste. (2)The segmented porosity of the deteriorated mortar was increased by approximately ten times

  • f that of non-deteriorated one. Especially the

effective porosity was increased by approximately twenty times. The diffusion tortuosity was 4 for deteriorated mortar.

slide-37
SLIDE 37

Conclusions 2/2 Conclusions 2/2 Conclusions 2/2

(3) For cement pastes as the CaO/SiO2 ratio was reduced from 3.6 to 1.8 the effective porosity was increased from 0.14 to 0.33 while the diffusion tortuosity was reduced from 41 to 7. (4) Potential applications to predict transport properties such as diffusivity and permeability are being considered.

slide-38
SLIDE 38

Acknowledgments

Assistances from Dr. Nakashima and Dr. Nakano from AIST

  • Dr. K. Uesugi and Dr. M. Uesugi from SPring‐8, JASRI