Frost resistance and nano-structure change of C-S-H of ...

Frost resistance and nano-structure

change of C-S-H of concrete

subjected dry-wet cycles

2010.11.11 in Dalian, China

1

Yukio HAMA Muroran Institute of Technology

Simulation model for durability design

Permeability

Performance prediction system

Mechanism of frost deterioration

Mixture Materials

Neutralization

1. Introduction

2

Weathering condition

Pore structureDiagnosis

technique

Equivalent cycles to ASTM C666 A

Temperature Humidity

Frost damage

Evaluation of environmental condition

Moisture in concrete

Simulation model for durability design

Permeability

Performance prediction system

Mechanism of frost deterioration

Mixture Materials

Neutralization

1. Introduction

3

Weathering condition

Pore structureDiagnosis

technique

Equivalent cycles to ASTM C666 A

Temperature Humidity

Frost damage

Evaluation of environmental condition

Moisture in concrete

2. Degradation of Frost Resistance by Aging

Outline of experimentConcrete Specimens : Total 43 kinds

High Fluidity Concrete : 24 kinds

(W/B=32〜50%, Air content=2 and 4.5%)

High Strength Concrete : 7 kinds

(W/C=28〜37%, Air content=1〜5%)

Normal Strength Concrete : 12 kinds

4

Normal Strength Concrete : 12 kinds

(W/C=45〜55%, Air content=2〜6%)

Curing condition before freeze/thaw test

a. 2 weeks in water

b. Outdoor exposure (exposure period : 7 to 12 years)

Freezing and Thawing Test : ASTM C666 A method

60

80

100HPC

HSC

NSC

Durability factors before and after outdoor exposure


Dura

bil

ity

fac

tor

(Aft

er e

xp

osu

re)

5

0

20

40

60

0 20 40 60 80 100

Durability factor

(Before exposure : 2 weeks in water)

Dura

bil

ity

fac

tor

(Aft

er e

xp

osu

re)

Durability factor

(Before exposure:2weeks in water)

60

80

100

HPC

HSC

NSC

After exposure

60

80

100

Relationship between air content and durability factor


Dura

bil

ity

fac

tor

Dura

bil

ity

fac

tor

6

0

20

40

0 1 2 3 4 5 6 7

Air content (%)

0

20

40

0 1 2 3 4 5 6 7

Air content (%)

HPC

HSC

NSC

Before exposure

Dura

bil

ity

fac

tor

Dura

bil

ity

fac

tor

Air content (%) Air content (%)


The frost resistance of non-AE HPC is often evaluated to be

excellent when the drying condition is approx. 20C.

In the actual outdoor environment,

However

7

In the actual outdoor environment,

the frost resistance may be degraded by aging.

Why

micro-cracks ?

pore structure ?

nanostructure in C-S-H ?

10-6 10-310-9 10-0

nm µm mm m

Frost

resistanceMicro

cracksPore

structuresNanostructuresCIF


8

Degradation Mechanism of Frost Resistance by Aging

Adolphs & Setzer

structures CIFMicroscope

MIP

Under water weighing

NMR,

H2O sorption

ESW model

Nanostructures of CSH Pore structures Micro cracks

3. Effects of Drying and Wetting Cycles

W/C Air s/a

Unit weight

(kg/m3) SP AE

(％) (％) W C S G (C×％） (C×％）

2N 0.25 1 39.3 175 700 623 968 1.3 1*

2A 0.25 4 36.1 175 700 543 968 1.3 0.2*

5N 0.5 1 48.9 175 350 919 968 0.6 0

5A 0.5 4 46.6 175 350 839 968 0.6 0.4

Outline of experiment

Mixture of Concrete

5A 0.5 4 46.6 175 350 839 968 0.6 0.4

*：Air reduce agent

9

Air Spacing factor* Slump Slump Flow Compressive Strength

（％）（µm）（cm）（mm） at 14days （MPa）

2N 0.8 728 － 670×705 93.1

2A 4.1 323 － 770×730 87.7

5N 1.8 741 11.5 － 41.5

5A 3.1 373 19.2 － 68.5

* : ASTM C 457 The linear traverse method

Basic Properties of Concrete

Curing condition

Water curing Air curing or Dry-wet cycles

I 2 weeks at 20oC Air curing for 3months at 20

oC

Curing Conditions before Freeze / Thaw (CIF Test)


10

M 2 weeks at 20oC 12 dry-wet cycles of air curing for 5 days at 50

oC

and water curing for 2days at 20oC

S 2 weeks at 20oC 12 dry-wet cycles of air curing for 5 days at 80

oC

and water curing for 2days at 20oC

0

20

40

60

80

100

120

RDM (%)

5N－I5N－M5N－S

0

20

40

60

80

100

120

RDM (%)

5A－I5A－M5A－S

Change of RDM with freeze-thaw test (CIF test)


11

0

0 20 40 60

Number of freeze/thaw cycles

0

0 20 40 60


0

20

40

60

80

100

120

0 20 40 60

RDM (%)


2N－I2N－M2N－S

0

20

40

60

80

100

120

0 20 40 60

RDM (%)


2A－I2A－M2A－S

0

20

40

60

80

100

120

RDM (%)

5N－I5N－M5N－S

0

20

40

60

80

100

120RDM (%)

5A－I5A－M5A－S

Relationship between RDM and water uptake


12

-1.0 -0.5 0.0 0.5 1.0

Water uptake (%)

0

-1.0 -0.5 0.0 0.5 1.0Water uptake (%)

0

20

40

60

80

100

120

-1.0 -0.5 0.0 0.5 1.0

RDM (%)

Water uptake (%)

2N－I2N－M2N－S

0

20

40

60

80

100

120

-1.0 -0.5 0.0 0.5 1.0

RDM (%)

Water uptake (%)

2A－I2A－M2A－S

2000

2500

3000

surface scaling ( g/m

2)

I

M

curing condition

64668

Surface scaling by freeze-thaw test (CIF test)

I M S


13

0

500

1000

1500

2000

5N 5A 2N 2A

surface scaling ( g/m

kind of concrete

M

S

Specimens after CIF test (5N)

Crack observation by the microscope

The number of micro-cracks crossed on traverse line was counted under a microscope at

50 times magnification modified ASTM C457 (Linear traverse method)

250

300

350

Degree of cracking

I M S

curing condition


0

50

100

150

200

250

5N 5A 2N 2A

Degree of cracking

(point/m)

Concrete type

I M S

14

0.00

0.01

0.02

0.03

0.04

0.05

0.06

pore volume (cc/g) 5N－I

5N－M

5N－S

0.00

0.01

0.02

0.03

0.04

0.05

0.06

Pore volume (cc/g) 5A－I

5A－M

5A－S

Total pore volume by MIP


15

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.001 0.01 0.1 1 10 100 1000

Pore volume (cc/g)

Pore diameter ( µm)

2N－I

2N－M

2N－S

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.001 0.01 0.1 1 10 100 1000

pore volume (cc/g)

Pore diameter (µm）

2A－I

2A－M

2A－S

0.001 0.01 0.1 1 10 100 1000

pore diameter (µm)0.001 0.01 0.1 1 10 100 1000

Pore diameter (µm)

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.001 0.01 0.1 1 10 100 1000

Pore volume (cc/g)

5N－I

5N－M

5N－S

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.001 0.01 0.1 1 10 100 1000

Pore volume (cc/g)

5A－I5A－M5A－S

Pore size distribution by MIP


16

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.001 0.01 0.1 1 10 100 1000

pore volume (cc/g)

Pore diameter (µm)

2N－I

2N－M

2N－S

0.001 0.01 0.1 1 10 100 1000

Pore diameter (µm)

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.001 0.01 0.1 1 10 100 1000

Pore volume (cc/g)

pore diameter (µm)

2A－I

2A－M

2A－S

0.001 0.01 0.1 1 10 100 1000

Pore diameter (µm)

Drying and wetting

Micro-cracks developed at aggregate-matrix interfaces.

Water uptake during freeze-thaw cycles increased.


Micro-cracks developed at aggregate-matrix interfaces.

Pore structure became coarser.

Why ?

17

Experiment procedure

Water

20°C 4w35W20

40 mm

Cement Paste (OPC,W/C=0.35)

Sample name

Dry Wet

80 mm

20°C 1d

4. Frost Resistance and Nano-structure Change of C-S-H

18

Water

20°C 2w

Air

30°C 5d

Air

50°C 5d

Air

50°C 4w

Water

20°C 2d

Water

20°C 2d

4 cycles35DW30

35DW50

35D50

160 mm

40 mm

4 cycles

Dry Wet

Test methods

Item Method

Cracking during environmental

changes

RDM

(flexural vibration methods)

Frost resistanceRILEM CIF test

(RILEM TC 176-IDC, 2004)

Mercury Intrusion Porosimetry (MIP)


19

Pore size distributionMercury Intrusion Porosimetry (MIP)

(Micromeritics Auto-pore 9200)

Total pore volume and

true densityUnder-water weighing

Specific surface area

(BET,ESW)

H2O sorption isotherm

(BEL Japan, BELSORP 18 PLUS-T)

Silicate anion structure29Si NMR MAS

(Bruker, Biospin Avance 400)

60

80

100

120

RD

M （％） 35W20

35DW3035DW5060

80

100

120

RD

M （％） 35W20

35DW3035DW50

Micro-cracks during environmental changesMicro-cracks during environmental changes

Micro-cracks !


20

0

20

40

0 4 8 12 16 20 24 28

Test duration of environmntal change(days)

RD

M

35DW5035D50

Dry D Wet W W WD D D

0

20

40

0 4 8 12 16 20 24 28

Test duration of environmntal change(days)

RD

M

35DW5035D50

Dry D Wet W W WD D D

Micro-cracks !

SpecimenMicro-

cracks

Frost

resistance

35W20 No cracks Excellent

35DW30 Cracks Excellent

35DW50 Cracks Poor

-10

-8

-6

-4

-2

0

2

4

-7 0 7 14 21 28Test duration (days)

Wa

ter

up

tak

e r

ate

（％）

35W2035DW3035DW5035D50

Capillary

suction

Freezing

& Thawing

-10

-8

-6

-4

-2

0

2

4

-7 0 7 14 21 28Test duration (days)

Wa

ter

up

tak

e r

ate

（％）

35W2035DW3035DW5035D50

Capillary

suction

Freezing

& Thawing

Water uptakeWater uptake Micro-ice-lens pump 4. Frost Resistance and Nano-structure Change of C-S-H

21

35D50 Cracks Poor

0

20

40

60

80

100

120

0 4 8 12 16 20 24 28 32 36 40 44 48 52 56Number of freeze/thaw cycles

RD

M （％）

35W2035DW3035DW5035D50

0

20

40

60

80

100

120

0 4 8 12 16 20 24 28 32 36 40 44 48 52 56Number of freeze/thaw cycles

RD

M （％）

35W2035DW3035DW5035D50

Test duration (days)Test duration (days)

RDMRDM

Micro-cracks

Frost damage

Micro structure ?

0.00

0.02

0.04

0.06

0.08

0.10

1 10 100 1000 10000 100000

Cu

mu

lati

ve p

ore

vo

lum

e (

cm

3/g

)

35W20

35DW30

35DW50

35D50

0.00

0.02

0.04

0.06

0.08

0.10

1 10 100 1000 10000 100000

Cu

mu

lati

ve p

ore

vo

lum

e (

cm

3/g

)

35W20

35DW30

35DW50

35D50

Total pore volume by MIP (8nm ≤ D)

35W2035W20 < 35DW3035DW30 < 35DW5035DW50 < 35D5035D5035W2035W20 < 35DW3035DW30 < 35DW5035DW50 < 35D5035D50


22

1 10 100 1000 10000 100000

Pore diameter (nm)

0.00

0.05

0.10

0.15

1 10 100 1000 10000 100000

Pore diameter (nm)

dV

/dlo

gD

(cm

3/g

·µm

)

1 10 100 1000 10000 100000

Pore diameter (nm)

0.00

0.05

0.10

0.15

1 10 100 1000 10000 100000

Pore diameter (nm)

dV

/dlo

gD

(cm

3/g

·µm

)

Peak diameter

10nm 100nm

Coarsening pore structure

Dry/Wet or Dry

35W2035W20 < 35DW3035DW30 < 35DW5035DW50 < 35D5035D5035W2035W20 < 35DW3035DW30 < 35DW5035DW50 < 35D5035D50

Specimen

Apparent

density

ρap (g/cm3)

Apparent

specific

volume

vap (cm3/g)

True

density

ρtr (g/cm3)

True specific

volume

vtr (cm3/g)

Total pore

volume

Vtotal (cm3/g)

35W20 1.72 0.581 2.34 0.427 0.154

35DW30 1.71 0.583 2.41 0.415 0.168

35DW50 1.76 0.568 2.50 0.400 0.169

35D50 1.79 0.560 2.56 0.390 0.169

0.60.6 Dry/Wet or Dry


23

0.0

0.2

0.4

0.6

35W20 35DW30 35DW50 35D50

Specimens

Vo

lum

e o

f p

ore

or

soil

d (

cm3/g

)

(Vtotal - VHg):

d < 8 nm *1

VHg:

d > 8nm *2

vtr: True

specific volume

of C-S-H in

hcp *3

Po

reS

oli

d

0.0

0.2

0.4

0.6

35W20 35DW30 35DW50 35D50

Specimens

Vo

lum

e o

f p

ore

or

soil

d (

cm3/g

)

(Vtotal - VHg):

d < 8 nm *1

VHg:

d > 8nm *2

vtr: True

specific volume

of C-S-H in

hcp *3

Po

reS

oli

d

by MIP

Dry/Wet or Dry

make denser C-S-H

shrunk!

coarsening pore

structure

nanostructure?

Kamada 、1996

20

40

60

80

100

120

CIF耐久性指数

W/C=0.35

W/C=0.55

35W20 (CIF耐久性指数108)

35DW30 (99)

35D50 (22)35DW50 (15)

0.02（cc/g)

0.02（cc/g)


24

0

20

0 0.02 0.04 0.06 0.08 0.1 0.12

細孔直径40～2000nmの細孔量（cc/g)

35D50 (22)35DW50 (15)

55W20 (14)55DW30 (10)

55DW50 (6)

Kamada 、1996

Change of micro structure

by W/C and age


by W/C and age


by drying and wetting


by drying and wetting

Degradation of frost resistance In this study

29Si MAS NMR

O

O

SiO44－ tetrahedron

Q0

Q3

Q1

un-hydrated

cement

silicate anion silicate anion chain

Q1Q2

Bridging structure


25

ＳＳＳＳｉｉｉｉ O

O

O

Qn: number of coordination

Q1 Q1

Q3

Qn

Q3

Q1

Q1

Q2

dimer

n = 0 - 4Q2

Q1 Q1Q2

chain

0%

50%

100%

35W20 35DW30 35DW50 35D50

Rel

ativ

e p

eak

in

ten

sity

(%

)

Q0

Q1

Q2P

Q2CaSilicate anion structure of C-S-H （Klur et al.1998）

Ca Ca Ca Ca Ca

H+Q1 Q2CaQ2p

Ca Ca Ca Ca Ca

Ca2+ Q2i

Q2Ca; -85ppmQ2i; -84ppmQ2p; -82ppm

CaO layer

Silicate chain

Q1; -79ppm


26

35W20 35DW30 35DW50 35D50

-120-100-60

(ppm)

-80

Q1

39.6

-79.5

Q2p

19.5

-82.1

Q2Ca

22.0%

-85.5 ppm

Q0

18.9

-72.6

35W20

-120-100-60

(ppm)

-80

Q1

45.0

-80.0

Q2p

18.8

-83.6

Q2Ca

23.8%

-86.5 ppm

Q0

12.3

-72.7

35DW30

-120-100-60

(ppm)

-80

Q1

34.6

-80.1

Q2p

20.0

-83.3

Q2Ca

31.2%

-86.4 ppm

Q0

14.2

-72.9

35DW50

-120-100-60

(ppm)

-80

Q1

15.8

-79.5

Q2p

16.4

-81.8

Q2Ca

55.9%

-85.5 ppm

Q0

11.9

-73.2

35D50

Q2Ca

2Ca2i2p1

Dry/Wet or Dry at 50°C

Polymerization of C-S-HPolymerization of C-S-HCa Ca Ca Ca

Q1

Q2Ca

Q2p

Ca Ca CaCa Ca Ca

Q1

Q2Ca

Q2p

29Si NMR & Pore

0.05

0.10

0.15

0.20

Po

re v

olu

me

（cm

3/g

)

35W20

35DW5035DW30 35D50

Vtotal : under water weighing

VHg : M I P (8nm ≤D)

0.05

0.10

0.15

0.20

Po

re v

olu

me

（cm

3/g

)

35W20

35DW5035DW30 35D50

Vtotal : under water weighing

VHg : M I P (8nm ≤D)

2.2

2.3

2.4

2.5

2.6

2.7

Tru

e d

ensi

ty o

f C

-S-H

in

hcp

,

ρtr

（g

/cm

3)

35W20

35DW50

35DW30

35D50

ρtr = 1/vtr

(a)

2.2

2.3

2.4

2.5

2.6

2.7

Tru

e d

ensi

ty o

f C

-S-H

in

hcp

,

ρtr

（g

/cm

3)

35W20

35DW50

35DW30

35D50

ρtr = 1/vtr

(a)


27

0.00

30 40 50 60 70 80

Relative peak intensity of Q2total by 29

Si MAS NMR

0.00

30 40 50 60 70 80


Si MAS NMR

Polymerization of C-S-H

Coarsening pore of 8nm≤ D

Shrinkage or aggregation

2.2

30 40 50 60 70 80


Si MAS NMR

0.35

0.40

0.45

30 40 50 60 70 80


Si MAS NMR

Tru

e sp

ecif

ic v

olu

me

of

C-S

-H

in h

cp ,

vtr

（cm

3/g

)

35W20

35DW50

35DW30

35D50

vtr = 1/ρtr

(b)

2.2

30 40 50 60 70 80


Si MAS NMR

0.35

0.40

0.45

30 40 50 60 70 80


Si MAS NMR

Tru

e sp

ecif

ic v

olu

me

of

C-S

-H

in h

cp ,

vtr

（cm

3/g

)

35W20

35DW50

35DW30

35D50

vtr = 1/ρtr

(b)

H2O sorption isotherm

2

4

6

8

　ad

sorb

ed,

nad

s (m

mo

l/g

)

35W2035DW3035DW5035D50

2

4

6

8

　ad

sorb

ed,

nad

s (m

mo

l/g

)

35W2035DW3035DW5035D50 Dry/Wet or Dry

decrease of H2O

adsorbed


28

0

0 0.2 0.4 0.6 0.8 1

Relative pressure （P/Ps）

H2O　

0

0 0.2 0.4 0.6 0.8 1

Relative pressure （P/Ps）

H2O　

further analysis by ESW model (Adolphs & Setzer, 1996)

ESW Φ (Excess Surface Work)

adsorbed

-6

0

0 2 4 6 8

H2O adsorbed nads (mmol/g)E

SW

Φ (

J/g

)

35W2035DW3035DW5035D50

(a)

n mono

-6

0

0 2 4 6 8

H2O adsorbed nads (mmol/g)E

SW

Φ (

J/g

)

35W2035DW3035DW5035D50

(a)

n mono

S1: at mono-layer

S2: at multi-layer

Sn: specific surface area calculated from reciprocal slope

ESW model


29

4

6

8

10

0 2 4 6 8H2O adsorbed, nads (mmol/g)

ln|∆

µ|

35W2035DW30

35DW5035D50

(b)

mono-layer multi-layer

S2

S1

-12

mono

4

6

8

10

0 2 4 6 8H2O adsorbed, nads (mmol/g)

ln|∆

µ|

35W2035DW30

35DW5035D50

(b)

mono-layer multi-layer

S2

S1

-12

mono

Dry/Wet or Dry

decrease of S2

layered structure

100

150

Sp

ecif

ic s

urf

ace

area

by

O)

(m2/g

)

S1100

150

Sp

ecif

ic s

urf

ace

area

by

O)

(m2/g

)

S1

polymerization & Sn


30

0

50

30 40 50 60 70 80 9029

Si MAS NMR Q2 total peak

Sp

ecif

ic s

urf

ace

area

by

ES

W (

H2O

) (m

S2

0

50

30 40 50 60 70 80 9029

Si MAS NMR Q2 total peak

Sp

ecif

ic s

urf

ace

area

by

ES

W (

H2O

) (m

S2

35W20（20℃水中）

基本ユニット

表４－４より，

　(Q2Ca+Q2i)/Q1=1

　重合度 = 4

（ａ）

Globule

シリケートアニオン鎖

Q1 Q2Ca

CaO層

0.73nm

（Jennings8), 2000 より一部転記）

LD C-S-H

LD C-S-HGlobule

Globule

【【【【Before Drying】】】】

JenningsJennings


31

約6 nm

Q1 Q2CaQ2i

r ≒ 1 nm

Globule

N2吸着，

毛細管凝縮可約20 nm

層状構造を持たない

Jennings’s Colloid ModelJennings’s Colloid Model

Results of NMRResults of NMR

Modified Colloid Model

considering

Nanostructure of C-S-H

Modified Colloid Model

considering

Nanostructure of C-S-H

35D50（50℃乾燥）

表４－４より，

　(Q2Ca+Q2i)/Q1=4.5

　重合度 = 11

（b）

重合で形成されたGlobule

重合で形成された基本ユニット

重合後のC-S-Hの概念図

0.73nm

重合で形成されたLD C-S-H

Coarsening

pore structure

Coarsening

pore structure

Development

layered structure

Development

layered structure

【【【【After Drying】】】】


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約4 nm

N2吸着による

毛細管凝縮なし。水銀圧入可約20 nm

層状構造

ｂ軸

a軸

Modified Colloid Model considering Drying EffectModified Colloid Model considering Drying Effect

Polymerization

of C-S-H

Polymerization

of C-S-H

Coarsening pore

structure

Coarsening pore

structure

Polymerization

of C-S-H

Polymerization

of C-S-H

Development

layered structure

Development

layered structure

Dry/Wet or Dry (Aging)

Development layered structure

Polymerization of C-S-H


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Shrinkage or Aggregation of C-S-H

Coarsening pore structure

Degradation of frost resistance

5. Conclusions

1. Drying and wetting cycles or drying deteriorated the frost resistance .

2. The deterioration of frost resistance is attributed to coarsening of the pore structure and not to micro-crack formation.

3. The true density of the C-S-H in HCP became denser by drying-wetting cycles or drying, that is to say the C-S-H shrunk, that correlates to the coarsening the pore structure.

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4. 29Si-NMR shows that polymerizations of silicate anion structures of C-S-H in HCP progress with drying-wetting or drying.

5. The ESW model for H2O sorption isotherm shows that the specific surface area at multi-layer decreases with polymerizations.

6. The deterioration of frost resistance of HSC after outdoor exposure is probably affected by the change in nanostructure of C-S-H in HCP subjected to drying condition.

Thank you for your attention !

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Thank you for your attention !

Frost resistance and nano-structure change of C-S-H of ...

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