Analysis of Moisture Flow in Porous Building Materials Using X-ray Radiography

Tine van Besien

Staf Roels

Jan Carmeliet

Laboratory for Building Physics, Department of Civil Engineering

Analysis Moisture Phenomena

- weighing of samples

- moisture profiles --> destructive way

- -ray attenuation technique

- NMR-technique

...

Non-destructive methods:

--> measure point wise, interpolation time domain necessary

X-ray Radiography

)exp(0 oodry dII

)exp(0 wwoowet ddII

)exp( wwdry dI

)exp(w

owdrywet

dwII

)exp( wwdrywet dII

o

ww

o

ww

d

d

V

Vw

dry

wet

ow

w

I

I

dw ln

Resolution

dryw

ww IdR

11ln

Function of:

- material

- energy of the source

- sample thickness

calibration measurements

0

1

2

3

4

0 0.05 0.1

sample thickness d (m)

-ln(I/

Io)

waterceramic brickcalcium silicate plate

eq

Attenuation coefficients

0)(

d

ERw

w

w

w

woptd

1ln

0

2

4

6

8

10

12

14

0 0.005 0.01 0.015 0.02 0.025 0.03

sample thickness d (m)

reso

lutio

n R

w (

kg/m

³)

increasing energy

CERAMIC BRICK

50 keV

60 keV

85 keV

d opt

0

1

2

3

4

5

0 0.05 0.1 0.15 0.2 0.25

sample thickness d (m)

reso

lutio

n R

w (

kg/m

³)

increasing energy

CALCIUM SILICATE

70 keV

100 keV

85 keV

d opt

Experiments

- determination of moisture profiles

- redistribution of hydrophobic agent in material

- cracks

- heterogeneous materials

1D

2D

-100

0

100

200

300

400

500

600

700

800

900

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07

distance (m)

mo

istu

re c

on

ten

t (k

g/m

³)

Redistribution water-repellent

-5.00E-03

0.00E+00

5.00E-03

1.00E-02

1.50E-02

2.00E-02

2.50E-02

15 25 35 45 55 65 75 85

Aerated concrete

Crack in Brick Sample

Crack in Calcium Silicate sample

ProblemsUnstable source

-6.00E-01

-5.00E-01

-4.00E-01

-3.00E-01

-2.00E-01

-1.00E-01

0.00E+00

1.00E-01

2.00E-01

1 21 41 61 81 101

121

141

161

181

201

221

241

261

281

301

321

341

361

381

401

421

441

461

481

501

521

541

561

581

601

621

641

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0 100 200 300 400 500 600 700

-0.01

0

0.01

0.02

0.03

0.04

0.05

150 200 250 300 350 400 450 500

Reflections?

-2.00E-02

0.00E+00

2.00E-02

4.00E-02

6.00E-02

8.00E-02

1.00E-011 14 27 40 53 66 79 92 105

118

131

144

157

170

183

196

209

222

235

248

261

274

287

300

313

326

339

352

365

378

391

404

417

430

443

456

469

482

495

Combination

-0.05

0

0.05

0.1

0.15

0.2

0 100 200 300 400 500 600

Future experiments- water penetration through hydrophobic treated crack

- drying of crack