Problems of Concrete Structures and Effort toward ... · Problems of Concrete Structures and Effort...

Problems of Concrete Structures and Effort toward Durability Design in

Thailand

BySomnuk Tangtermsirikul, D.Eng.

ProfessorSchool of Civil Engineering and Technology

Interesting Statistics about Concrete in Thailand

World Cement Consumption

0200400600800

10001200

Consumption (million tons)

1994 1995 1996 1997 1998 1999 2000

Year

Others Americas Europe Asia

Cement Consumption in Asia

581.0

99.6

72.348.0 17.8

China India Japan Korea Thailand

Year 2000Unit : Million tons

Top 5 Countries

Cement Production in Asia

750.0

110.0

72.056.0 35.0

China India Japan Korea Thailand

Year 2003Unit : Million tons

Top 5 Countries

Per capita consumption in Thailand in 2004

Cement + Fly ash : about 450 - 500 kgConcrete : about 1 m3

Growth : about 10-15% or more from 2003

Some World Recordsin Thailand

Klong Tha Dan Dam– Highest amount of RCC utilization

5.5 million m3

– Highest amount of RCC placing in 1 day 15,000 m3

Fly Ash– Highest effective utilization in concrete

80% of total fly ash production

KhlongKhlong Ta Dan Dam Project with 5.5 million mTa Dan Dam Project with 5.5 million m33 of RCCof RCC

Consumption/Production (%)

0.0130.0330.0730.5213.33

26.6733.33

46.67

6070

84

0102030405060708090

'94 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04

*

Computed based on annual production of 3 million tonsComputed based on annual production of 3 million tons

However, those are just in term of quantity.

Still many problems regarding quality.

Central Thailand• Bangkok• Nakornsawan• Ratchaburi• Lob-Buri• Ayudtaya• Samutsongkarm• Pathum Thani

Seaside areas • Samutprakarn• Cholburi

Research area

Number of structures Percent

Central Thailand 159 87.85Seaside area 22 12.15Total 181 100.00

Environmental condition

Classification

7-year Surveys on Situation of Concrete Structures in Thailand

• Location : central and eastern parts of Thailand (different environment)

• Age of structures : from during construction until very aged ones

• Finding : Many problems on low quality structures

Problems• Construction of new structures• Already existing structures

Problems occurs in all Steps of Practice

• Analysis and Design• Materials• Construction• Protection and Maintenance

Analysis and Design Problem

Cracks

Strength design with no durability consideration

Material Problems

Self-restraint thermal crack

Use Concrete with Segregation

Drying Shrinkage

Alkali-Aggregate Reaction

Biological Degradation

Problems on Poor Construction

Plastic Shrinkage

Cracks due to Plastic Settlement

Early steel corrosion due to Carbonation

(not enough concrete cover)

Steel Corrosion(too small concrete cover)

Maintenance Problems

Chloride Induced Corrosion(Early Maintenance Program is Required)

Chloride induced Steel Corrosion

Severe Steel Corrosion due to Carbonation

Incompatible repair material

Incipient Anode Problem

Picture from SIKA (Thailand)

Improper active crack repair using epoxy mortar with low deformability

Pictures from SIKA (Thailand)

Failure of Coating

• Swelling and debonding of the coating material due to moisture behind the coat

Pictures from SIKA (Thailand)

Solution

To obtain durable structures • For New Construction

– Good Analysis and Design (new PWCP design acts)– Good Materials (new TCA material spec.)– Good Construction (?)– Good Protection and Maintenance

• For Already Existing Structures*– Monitoring, Protection, Maintenance, Repair,

Strengthening

* Not Today’s topic

Analysis and Design

Design considering long term properties(durability, creep, fatigues, ductility),

easiness of construction and maintenance

A new building acts enforcing both short term and long term properties of

structures by Department of Public Works & Urban Planning

(Effective in 2005)

Materials

Low energy consumption materials

Wastes & recycling

Proper material for certain types of construction and environment

Performance based analysis and design for concrete mix proportion

Supported by a new Specification established

by DPW&UP

0

10

20

30

0 20 40 60 80 100 120Age(year)

Val

ue o

f det

erio

ratio

n

Cholburi

0

10

20

30

0 20 40 60 80 100 120Age(year)

Val

ue o

f det

erio

ratio

n

Bangkok

Relation between value of deterioration and age of column(Steel Corrosion Problem)

Structures in Cholburi

Central Thailand• Bangkok• Nakornsawan• Ratchaburi• Lob-Buri• Ayudtaya• Samutsongkarm• Pathum Thani

Seaside areas • Samutprakarn• Cholburi

Research area

Number of structures Percent

Central Thailand 159 87.85Seaside area 22 12.15Total 181 100.00


Classification

Chloride induced Corrosion

Structures in Bangkok

Carbonation induced steel corrosion

Carbonation induced steel corrosion

Various types of Special Concretelaunched by Ready-mixed companies

- Low heat concrete- Marine concrete (Cl- and sulfate resistance)

- Sulfate resisting concrete- Frost resistance concrete - Self-compacting concrete

- etc.

Extend Service Life

How long ?

Performance Based Analysis and Design of Concrete Mix Proportion

(Computer Software for Mix Design)

At SIIT, At SIIT, ThammasatThammasat UniversityUniversity

-Workability

Performance Prediction Models for Analysis and Design of Concrete Mix Proportion

Overall Concrete Properties

Fresh Plastic Early Age Hardened Long term

-Bleeding

-Settlement

-Plastic shrink

-Setting

-Temperature

-Auto shrink

-Strength

- f’c

- ft

- fr

- Ec

− ν

Durability- Drying shrink- Cl Corrosion- Carbonation- AAR- Sulfate attack-Acid attack-Freeze-Thaw- ErosionOthers- Creep- Fatigue

Previous design practice

Examples of Computer Software for Performance Based Analysis

and Design

2001

EGAT and SIIT

For workability and strength design

A Workability Prediction Model for Fly Ash Concrete

Overall Concrete Properties

Fresh Plastic Early Age Hardened Long term

-Bleeding

-Settlement

-Plastic shrink

-Setting

-Temperature

-Auto shrink

-Strength

- f’c

- ft

- fr

- Ec

− ν

Durability- Drying shrink- Cl Corrosion- Carbonation- AAR- Sulfate attack-Acid attack-Freeze-Thaw- ErosionOthers- Creep- Fatigue

Previous design practice

-Workability

**Chemical admixtures

**Shape and porosity of powder

*

*

*

Stp

*

*

*

StaWfrγAnalytical factor

Practical factor

*Concrete temperature

**Powder content

**Unit water content

*Size and fineness of powder

**Gradation of powders and aggregate

*Maximum size and gradation of aggregate

*sand to aggregate ratio

Factors affecting consistency and workabilityFactors affecting consistency and workability

-25-20-15-10-505

10152025

0 20 40 60 80 100 120 140

Free water content (kg / m3)

Slum

p (c

m)

γ =1.1

γ =1.2

γ =1.3

γ =1.4

W0

SL = αSL(Wfr-W0)SL = αSL(Wfr-W0)

Free water

Minimum free water content required for initiating slump

Slope of slump-free water content curve

Model FormulationModel Formulation

The slope of slumpThe slope of slump--free water content curvefree water content curve•• Concrete with more paste will have higher slumpConcrete with more paste will have higher slump

0.0

0.1

0.2

0.3

0.4

1.0 1.2 1.4 1.6 1.8

γ

α

κ−γ−γ−γ−γ=α )94.1492.4374.4634.2157.3( 234SL

Effect of void content

Free Water Content in Mixture (Wfr)

SL = αSL (Wfr - W0)SL = αSL (Wfr - W0)

WWfrfr = W= Wuu -- WWrprp -- WWrara′′

Total waterTotal water

Water restricted by powdersWater restricted by powdersWWrprp = = ΣΣ ββpi pi WWpipi

Water restricted by aggregatesWater restricted by aggregatesWWrara

′′ = = ββs s ′′ WWss

′′ + + ββgg′′ WWgg

′′

Concept : water which has effect on workability is the water notrestricted by all solid particles

Water Retainability of Powders

Powder will retain more water in and at the surface of the particles when it has larger surface area, porosity and irregularity (shape). For ash-type powders, higher LOI also results in higher water retainability. Higher temperature will increase water retainability of cementitious powders like cement, fly ash, rice husk ash, etc. but affects very little on non-reactive powder like limestone powder.

Water Water RetainabilityRetainability of Fly Ashof Fly Ash

ρ

δψξ=β 53.0

41.005.0p

74.0

pS

185.0

Specific surface area of powder (Sp), cm2/g

Wat

er re

tain

abili

tyof

pow

der

0.15

0.17

0.19

0.21

0.23

0.25

0 3000 6000 9000 120000.10

0.20

0.30

0.40

0.50

0 3000 6000 9000 12000

δ = 4%

δ = 2%δ = 1%

ρ = 1.8ρ = 2.0ρ = 2.3ρ = 2.7

LOI (δ), surface area (Sp), porosity, shape factor

Specific gravity (ρ)

βp = ƒ ( porosity, surface area)

βagg′ = ƒ ( surface area)

βagg′

βagg′ = 0.0012 (Sagg) 0.92

Specific surface area of aggregate, Sagg (cm2/kg)

0 .0 0

0 .0 1

0 .0 2

0 .0 3

0 .0 4

0 .0 5

0 2 0 0 0 0 4 0 0 0 0 6 0 0 0 0 8 0 0 0 0

Water Water RetainabilityRetainability of Aggregatesof Aggregates

• More amount of cement results in more amount of void for fillable powder to fill

Additional free water due to filling effect (Additional free water due to filling effect (WWaaaa))

• Fine particles of fly ash can fill in the voids among cement particles, driving out some additional free water

WWfrfr = W= Wuu -- WWrprp -- WWrara′′ + + WWaaaa

water(Waa)

Cement

Cement Cement

Spherical particles(lubricating)

Fillable particles(Filling)

Vfill = F x VcVfill = F x Vc

• Filling ability depends on– Size : smaller fills easier – Shape : spherical fills easier– Content : more filler content (in this case fly

ash is considered as filler) results in more possibility to fill (but not beyond the capacity of voids among cement).

Filling Ability

0.00

0.03

0.06

0.09

0.12

0.15

0.5 1.0 1.5 2.0 2.5 3.0

R'

Fr = 0.05

r = 0.10

r = 0.25

r = 0.35

r = 0.05

r = 0.10

r = 0.25

r = 0.35

0.00

0.10

0.20

0.30

0.40

0 1 2 3 4 5

R'

FLimestone Powder

Fly Ash

a)Rexp(69.025.0F

′−=

25.0

3.3

r6.0a

1R31R

=

ψ−

+=′

Filling coefficient (F)Filling coefficient (F)

Smaller size

-2 0

-1 5

-1 0

-5

0

5

1 0

1 5

2 0

2 5

0 2 0 4 0 6 0 8 0 1 0 0 1 2 0 1 4 0

Free water content, W fr (kg/m3)

Slum

p (c

m)

γ=1.4

γ=1.3

γ=1.1

γ=1.2W 0

α

W0 = ƒ( Seff )WW00 = = ƒƒ(( SSeffeff ))

SL = αSL (Wfr - W0)SL = αSL (Wfr - W0)

Minimum Free Water Content Required for Initiating slump (W0)

Seff = ηa Sagg + ηp SpowSeff = ηa Sagg + ηp Spow

(Spow) x ηp ƒ(Sagg)

Seff

Effective surface areaEffective surface area

Coarse aggregates

Fine aggregates

Powder particles

Powder particles contact on aggregate surface

Aggregate contacts can be disturbed by powder particles

(Sagg) x ηa ƒ(Vpow)

0

20

40

60

80

0 1 2 3 4 5 6Seff ( x 107 cm2/m3)

W0 (

kg/m

3 )

W0 = 8 x 10 –5 (Seff) 0.76W0 = 8 x 10 –5 (Seff) 0.76

Lubrication Effect

Air bubbles and spherical or semi-spherical properties of fly ash particles can introduce lubrication to other solid particles in the concrete mixture. This effect reduces friction among the solid particles and then reduces Wo.

Lubrication of Lubrication of interparticleinterparticle frictionfriction

W0′ = WoL

Spherical particles - fly ash- Air bubbles

Solid particle

pa LLL,tCoefficiennLubricatio ×=

Lubrication coefficient of air bubbles

Lubrication coefficient of powder

Solid particle

Solid particle

84.0SV1054.3exp81.1L

ta

air7a −

××=

Lubrication coefficient of air bubblesLubrication coefficient of air bubbles

Air bubbleAggregate

AggregateAggregate

Surface area of airSurface area of air

Surface area of aggregatesSurface area of aggregatesLLaa

Volume of airVolume of air0.5

1.0

1.5

2.0

2.5

0.0 1.0 2.0 3.0 4.0 5.0 6.0

ta

air

SV

aφ

0.1

0.2

0.3

0.4

0.1 0.2 0.3 0.4

Tested Vair/Vp

Pred

icte

d V

air/

Vp

VinsolT-28303A

ϕ= Loi,,

bw,VfV pasteair

1

1.1

1.2

1.3

1.4

1.5

0 1 2 3 4 5 6R

L r = 0.15r = 0.25r = 0.35r = 0.15r = 0.25r = 0.35

1.0

1.1

1.2

1.3

1.4

0 1 2 3 4 5 6 7R

L ψ = 1 .4

ψ = 1 .3

ψ = 1 .2

ψ = 1 .1

ψ = 1 .0

Spherical particles(lubricating)

Cement

Cement Cement

Fillable particles(Filling)

L = 1 + (1.4 - ψ) (2.27 r 1.79) R (-0.93 r + 0.98)L = 1 + (1.4 L = 1 + (1.4 -- ψψ) (2.27 r ) (2.27 r 1.791.79) R ) R ((--0.93 r + 0.98)0.93 r + 0.98)

Lubrication coefficient of cement replacing powderLubrication coefficient of cement replacing powder

VerificationsVerifications

0

5

10

15

20

25

0 5 10 15 20 25

Tested Slump (cm)

Pred

icte

d Sl

ump

(cm

)

Loi = 1.24%

Loi = 4.24%

Loi = 7.60%

Comparison between the predicted and tested slump of concrete

containing various type of powder


containing various type of powder


containing various type of fly ash


containing various type of fly ash

0

5

10

15

20

25

0 5 10 15 20 25

Tested Slump (cm)

Pred

icte

d Sl

ump

(cm

)

Fly AshLimestone PowderRice Husk Ash

05

1015202530

0 5 10 15 20 25 30

Tested slump (cm)

Pred

icte

d sl

ump

(cm

)

Comparison between the predicted and tested slump of concrete with the application of air entraining agent

Comparison between the predicted and tested slump of concrete with the application of air entraining agent

Use of Water-reducing Efficiency and Setting Time for Time-Dependent Slump

Prediction

Use of WaterUse of Water--reducing reducing Efficiency and Setting Time Efficiency and Setting Time for Timefor Time--Dependent Slump Dependent Slump

PredictionPrediction

By

Somnuk Tangtermsirikul, D.Eng.

Water Reducing Efficiency (ϕ') of WRA

75

90

180

paste

40

quantity of water required to produce a flow diameter of 180 mm with 0.5% dosage of WRA

quantity of water required to produce a flow diameter of 180 mm without WRA

woa

wa

WW1' −=ϕ

Water Reducing Efficiency (ϕ') of WRA

Initial Setting time of cement with WRA

• The normal consistency and the initial setting time were determined in accordance with ASTM C 187-98 and C 191-99.

• The dosage of WRA was selected at 0.5% by weight of cement, which is the same dosage as the test for water-reducing efficiency

Verifications for Naphthalene

0

5

10

15

20

25

0 50 100 150

Time (min)

Slum

p (c

m)

T est (WRE=0.5%)Model (WRE=0.5%)Test (WRE = 0.8%)Model (WRE=0.8%)Test (WRE=1.0%)Model (WER=1.0%)

0

5

10

15

20

25

0 50 100 150

Time (min)

Slum

p (c

m)

T est (w/b=0.4)

Model (w/b=0.4)

Test (w/b=0.5)

Model (w/b=0.5)

0

5

10

15

20

25

0 50 100 150

Time (min)

Slum

p (c

m)

T est (w/b=0.4)

Model (w/b=0.4)

Test (w/b=0.5)

Model (w/b=0.5)

WRA = 0.5% (No fly ash)WRA = 0.5% (No fly ash) WRA = 0.5% (20% fly ash)WRA = 0.5% (20% fly ash)

W/b = 0.4 (No fly ash)W/b = 0.4 (No fly ash)

Verifications of Lignosulfonate

0

5

10

15

20

25

0 50 100 150

Time (min)

Slum

p (c

m)

T est (LignoII)

Model (LognoII)

Test (LognoIII)

Model (LognoIII)

0

5

10

15

20

25

0 50 100 150

Time (min)

Slum

p (c

m)

T est (LignoII)

Model (LognoII)

Test (LognoIII)

Model (LognoIII)

(No fly ash)(No fly ash)

(20% fly ash)(20% fly ash)

Mixture:

γ = 1.2, W/b = 0.5

WRA = 0.5%

Mixture:

γ = 1.2, W/b = 0.5

WRA = 0.5%

Verifications of Polycarboxylic

0

5

10

15

20

25

0 50 100 150

Time (min)

Slum

p (c

m)

T est (PolyIII)

Model (PolyIII)

Test (Poly II)

Model (PolyII)

0

5

10

15

20

25

0 50 100 150

Time (min)

Slum

p (c

m)

T est (PolyIII)

Model (PolyIII)

Test (Poly II)

Model (PolyII)

Mixture:

γ = 1.2, W/b = 0.4

WRA = 0.5%

Mixture:

γ = 1.2, W/b = 0.4

WRA = 0.5%

(No fly ash)(No fly ash)

(20% fly ash)(20% fly ash)

Fly Ash I

0

5

10

15

20

0 5 10 15 20

Test Slump (cm)

Pred

icte

d Sl

ump

(cm

)

init ial30 min60 min90 min120 min

Fly Ash II

0

5

10

15

20

0 5 10 15 20

Test Slump (cm)Pr

edic

ted

Slum

p (c

m)

init ial30 min60 min90 min120 min

Verification of Initial and Time dependent Slump of Fresh Concrete

(No admixtures, Normal temperature)

Verification of Slump Loss of Fresh Concrete(No admixtures, High temperature)

0

5

10

15

20

0 5 10 15 20

Test Slump (cm)

Pred

icte

d Sl

ump

(cm

)

0 min30 min60 min90 min120 min

A Compressive Strength A Compressive Strength

Prediction Model Prediction Model

for Fly Ash Concretefor Fly Ash Concrete

MODEL FORMULATIONMODEL FORMULATION

( )cf ' 28 daysCompressive strength at 28 days

( )c cf ' t (t) f '(28 days)= φ ⋅Compressive strength at any ages

Strength ratio for obtaining compressive strength at other ages

c

c

f '( t )( t )f '(28 days)

φ =

fc’(28 days) = α1log(CaOeff) + α2fc’(28 days) = α1log(CaOeff) + α2

Relationships among w/b, Relationships among w/b, CaOCaOeffeff, and f, and fcc’’(28 days)(28 days)

for Conventional Concretefc'( 28 days), MPa

0

10

20

30

40

50

60

70

1.9 2.1 2.3 2.5log (CaOeff)

w/b = 0.30w/b = 0.40w/b = 0.50

Effective Calcium Oxide Content in BindersEffective Calcium Oxide Content in Binders

)CaO(%

)CaO(%

f

f

e1

e1κ−

κ−

+

−=ϕ

Effectiveness of calcium oxide in fly ashEffectiveness of calcium oxide in fly ash

( ) ( )100

WCaO%WCaO%CaO ffcc

eff×⋅ϕ+×

=

effective unit calcium oxide content in concrete (kg/meffective unit calcium oxide content in concrete (kg/m33))calcium oxide content in cement (% by weight)calcium oxide content in cement (% by weight)calcium oxide content in fly ash(% by weight)calcium oxide content in fly ash(% by weight)cement content in concrete (kg/mcement content in concrete (kg/m33))fly ash content in concrete (kg/mfly ash content in concrete (kg/m33))

CaOCaOeffeff%%CaOCaOcc%%CaOCaOff

WWccWWff

==========

3.07fS0.0048 0.0245

3000 κ = +

Effectiveness of Fly AshEffectiveness of Fly Ash

cm2gcm2/gcm2/gcm2/g

Effectiveness of fly ash, ϕ

0.0

0.5

1.0

1.5

0 5 10 15 20 25 30CaOf

2600 410046007800

Ψ

−+=

3.31R31'R

c

p

SS

R = 25.0r6.0a =

Filling Effect of Fly Ash on fFilling Effect of Fly Ash on fcc´(28 days)(28 days)

in which

F = Filling CoefficientR = Specific surface areaSc = Specific surface area of cement

Sc = Specific surface area of filling powderr = replacement ratio of fly ashΨ = Shape factor

((TangtermsirikulTangtermsirikul, et al., 2001), et al., 2001)

Filling coefficient, F

0.00

0.05

0.10

0.15

0.20

0.25

0.0 1.0 2.0 3.0 4.0Specific surface area ratio, R

air-classified, r = 0.10air-classified, r = 0.20ground, r = 0.10ground, r = 0.20

Filling Effect of Fly Ash on fFilling Effect of Fly Ash on fcc’’(28 days)(28 days)

fc’(28 days) = α1log(CaOeff) + λF. α2

fc’(28 days) = α1log(CaOeff) + λF. α2

Filling Effect of fly ash on fFilling Effect of fly ash on fcc’’(28 days)(28 days)

cm2/g

cm2/g

F = 0.13F = 0.13F = 0.00F = 0.00

fc'( 28 days), MPa

0

10

20

30

40

50

60

70

1.9 2.1 2.3 2.5log (CaOeff )

fineness = 7800 fineness = 2600

Denser particle packing of binders

Denser particle Denser particle packing of packing of bindersbinders

Filling Effect of fly ash on y-intercept of the curvelog(CaOeff) - fc’(28 days), 1/λF

Filling Effect of Fly Ash on fFilling Effect of Fly Ash on fcc’’(28 days)(28 days)

F 4.91 1 3.24

11 (0.25 ) tan (357F )− −λ =

+ Ψ

ΨΨ = 1.05= 1.05ΨΨ = 1.20= 1.20

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0.00 0.05 0.10 0.15 0.20 0.25Filling Coefficient, F

air-classified fly ashground fly ash

Effect of ratio of paste to void volume Effect of ratio of paste to void volume

55.059.0 )b/w(74.1opt +=γ

void

paste

VV

=γ

χγ , Effect of γ on fc'(28 days)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2γ

w/b=0.40

w/b=0.60

3.68 2.21opt opt

1.12opt

optopt

1 [10.64(w / b) 2.38] ( ) ;

[11.97(w / b) ] ( )1 ;

7.57 exp[1.83( )]γ

− + ⋅ γ − γ γ ≤ γ

χ = ⋅ γ − γ− γ > γ + γ − γ

Highest fc’(28 days)Highest fc’(28 days)

Higher strength pasteHigher strength pasteLower strength pasteLower strength paste

Smaller Smaller reductionreduction

Effect of LOI of Fly Ash Effect of LOI of Fly Ash

paste

LOIVV

=η

100)/WLOI(%

100)/WLOI(%

V ffucfLOI

ρ×≈

ρ×=

LOI in fly ash nonLOI in fly ash non--reactive part in concretereactive part in concrete

CaOf = 1.58%CaOf = 14.01% CaOf = 23.64%

χLOI, Effect of LOI of fly ash on fc′(28 days)

0.7

0.8

0.9

1.0

1.1

0.000 0.005 0.010 0.015η

1.66LOI f1 155.75 [exp( 0.15 CaO )]χ = − − ⋅ η

This effect is not serious for highThis effect is not serious for high--CaOCaO fly ashfly ash

Effect of Entrained Air Effect of Entrained Air

air contentair content air contentair content

pastepaste

aggregatesaggregates

paste

airVV

=ξ

Same air content Same air content BUTBUT gives different effect on fgives different effect on fcc´(28 days)(28 days)

Effect of Entrained Air Effect of Entrained Air

χair, Effect entrained air on fc’(28 days)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.00 0.10 0.20 0.30Vair/Vpaste

1.70air 1 2.35χ = − ξ

2828--DAY COMPRESSIVE STRENGTH MODEL DAY COMPRESSIVE STRENGTH MODEL

F 4.91 1 3.24

11 (0.25 ) tan (357F )− −λ =

+ Ψ

for Conventional Concrete

3.68 2.21opt opt

1.12opt

optopt

1 [10.64(w / b) 2.38] ( ) ;

[11.97(w / b) ] ( )1 ;

7.57 exp[1.83( )]γ

− + ⋅ γ − γ γ ≤ γ

χ = ⋅ γ − γ− γ > γ + γ − γ

1.66LOI f1 155.75 [exp( 0.15 CaO )]χ = − − ⋅ η

1.70air 1 2.35χ = − ξ

2.07 1wr 1 (3.52 0.27) (0.005(w / b) ) tan (3.90 )− −χ = + Ω − ⋅ ⋅ ν

c 1 eff f 2 LOI wr airf ' (28days) [ log(CaO ) ] γ= α + λ ⋅α ⋅χ ⋅χ ⋅χ ⋅χ

Concrete containing Concrete containing original fly ashoriginal fly ash

Verifications for Conventional Concretes ModelVerifications for Conventional Concretes Model

Fineness = 2600 cm2/g Fineness = 4100 cm2/g Fineness = 4600 cm2/g

Predicted Strength (MPa)

0

10

20

30

40

50

60

0 10 20 30 40 50 60Tested Strength (MPa)

-15%

+15%


0

10

20

30

40

50

60


-15%

+15%


0

10

20

30

40

50

60


-15%

+15%


0

10

20

30

40

50

60


-15%

+15%


0

10

20

30

40

50

60


+15%

-15%


0

10

20

30

40

50

60


+15%

-15%


Concrete with Concrete with classified fly ash classified fly ash ((ΨΨ = 1.05)= 1.05)Concrete with Concrete with ground fly ashground fly ash ((ΨΨ = 1.20)= 1.20)


0

10

20

30

40

50

60


with classified fly ashwith ground fly ash

-15%

+15%


0

10

20

30

40

50

60


with classified fly ashwith ground fly ash

-15%

+15%


Air Entrained ConcreteAir Entrained Concrete High LOI Fly Ash ConcreteHigh LOI Fly Ash Concrete

+15%

-15%

+15%

-15%


0

10

20

30

40

50

60


LOI = 0.17%LOI = 4.50%LOI = 5.48%


0

10

20

30

40

50

60


air = 1%air = 4%air = 8%

)days28('f)t('f

)t(c

c=φStrength Ratio

Factor Effecting Strength Development of ConcreteFactor Effecting Strength Development of ConcreteSiOSiO22/CaO/CaO

w/bw/b

Filling Effect of fly ashFilling Effect of fly ash

Effect of waterEffect of water--reducing admixturereducing admixture

Compressive Strength Development ModelCompressive Strength Development ModelCompressive Strength Development Model

Verifications for the Strength Development ModelVerifications for the Strength Development ModelVerifications for the Strength Development Model

3 Days3 Days 7 Days7 DaysPredicted Strength (MPa)

0

5

10

15

20

25

30

35

40

0 5 10 15 20 25 30 35 40Tested Strength (MPa)

with original fly ashwith ground fly ashwith air -classified fly ash


0

10

20

30

40

50

0 10 20 30 40 50Tested Strength (MPa)


+15%

-15%

+15%

-15%

91 Days91 Days 180 Days180 Days


0

1020

30

40

5060

70

80

0 10 20 30 40 50 60 70 80Tested Strength (MPa)



0102030405060708090

100



+15%

-15%

+15%

-15%


365 Days365 Days


0

20

40

60

80

100



+15%

-15%


PERFORMANCE BASED PERFORMANCE BASED PREDICTION MODELPREDICTION MODEL:Temperature of Concrete:Temperature of Concrete

Total Heat Generation of Concrete

Temperature Gradient of Concrete

Temperature of Concrete

Specific Heat

Heat Conductivity

∫ ∆== TsHdtQ ρs : Specific Heatρ : Specific GravityH : Heat Generation rate per unit

volumeT : Temperature of concrete

HzT

yT

xTK

dtdTs +

∂∂

+∂∂

+∂∂

=

2

2

2

2

2

2

ρ

Heat Transfer Coefficient ( ) ( )extTTmnHTk −=+∇− .2

K : Heat conductivityH : Heat generation rate per unit volumen : Outward unit vector normal to the

surfacem : Heat transfer coefficient

Coefficient of expansion

Temperature Gradient of Concrete

Differential Expansion

Cracking Strain

Restrained Tensile Strain

Cracking

Modulus of Elasticity


C3A

Cement

Fly AshC2SC4AF

C3S

)t(Q)t(Q)t(Q)t(Q)t(Q)t(Q)t(Q)t(Q FAAFETCAETCAFCACSCSC 434323++++++=

Cumulative Heat Generation of Ettringite and MonosulphateCumulative Heat Generation of Cement CompoundsCumulative Heat Generation of Fly Ash

0102030405060708090

0 0.2 0.4 0.6 0.8 1

Time (Days)

QC

3AE

T (k

cal/k

g of

gyp

sum

)

2 % 3 % 4 %5 % 6 %

Heat Generation of Ettringite and MonosulfateFormation Reactions

0

20

40

60

80

100

0 2 4 6 8

Gypsum Content (% by weight of cement)

Qi,E

nd (k

cal/k

g of

gyp

sum

)

QC3AET,EndQC4AFET,End

QCQC33AETAET

0

5

10

15

20

25

0 0.2 0.4 0.6 0.8 1

Time (Days)

QC

4AFE

T (k

cal/k

g of

gys

um)

2 % 3 % 4 %5 % 6 %

QCQC44AFETAFET

Heat Generation of Cement

imax,ii

i wQ100

)t()t(Q ⋅⋅

α=

Degree of HydrationDegree of Hydration

020406080

100120140160180200

0 20 40 60 80 100Degree of Hydration, α i (%)

Qi (

kcal

/kg

of

the

com

poun

d)

QC3AQC3SQC4AFQC2S QCQC33S = 105 kcal/kgS = 105 kcal/kg

QCQC44AF = 85 kcal/kgAF = 85 kcal/kg

QCQC33A = 190 kcal/kgA = 190 kcal/kg

QCQC22S = 50 kcal/kgS = 50 kcal/kg

wi = wiowi = wio

wi = wio – wiET – wiMNwi = wio – wiET – wiMN

For CFor C33S and CS and C22SS

For CFor C33A and CA and C44AFAF

Heat Generation of Fly Ash

fmax,FA CaO%63.036Q ⋅+=

At max degree of At max degree of pozzolanicpozzolanic reactionreaction

Calcium Oxide in Fly AshCalcium Oxide in Fly Ash

50

60

70

80

90

100

0 10 20 30Calcium O xide Content in Fly Ash

(% by weight of fly ash)

QFA

,max

(kca

l/kg

of fl

y as

h)famax,FA

pozFA wQ

100)t(

)t(Q ⋅⋅α

=Fly Ash ContentFly Ash Content

Degree of Degree of PozzolanicPozzolanic ReactionReaction

Thermal Properties

)t(c)t(wc)t(wc)t(wc)t(wcwcw)t(c hphpfaufacucwfwssgg +++++=

( ) 0chyuc w)t(1)t(w α−= uc, ufa

hc, hfa

c(t) : specific heat of concrete at any time.ci : specific heat of i-th component of concretewi : weight of i-th component of concrete

Thermal Coefficients

Coarse aggregate

(Lime Stone)

Fine aggregate

(Sand)Water Cement Fly Ash Air Hydrated

Product *

Specific Heat (kcal/kg/ °C) 0.20 0.19 1.0 0.18 0.17 0.24 0.13

ASHRAE: American Society of Heat Refrigerating and Air Conditioning Engineering

* Back analysis

Specific Heat Model

( ) 0fapozufa w)t(1)t(w α−=

ThermocouplesThermocouples

Insulating Insulating materialmaterial

ContainerContainer

SpecimenSpecimenHot Hot waterwater

Data loggerData logger

Data LoggerData Logger Insulated ContainerInsulated Container

Apparatus for testing specific heat

Verification of Specific Heat Model

0.050.1

0.150.2

0.250.3

0.350.4

0.45

0 5 10 15 20 25 30

Time (Days)

Spec

ific

Hea

t (K

cal/k

g/o C) w/b = 0.25; r = 0 (Test)w/b = 0.40; r = 0 (Test)w/b = 0.25; r = 0 (Model)w/b = 0.40; r = 0 (Model)

0.050.1

0.150.2

0.250.3

0.350.4

0.45

0 5 10 15 20 25 30

Time (Days)

Spec

ific

Hea

t (K

cal/k

g/o C) w/b = 0.25; r = 0.3 (Test)w/b = 0.40; r = 0.3 (Test)w/b = 0.25; r = 0.3 (Model)w/b = 0.40; r = 0.3 (Model)

0.050.1

0.150.2

0.250.3

0.350.4

0.45

0 5 10 15 20 25 30

Time (Days)

Spec

ific

Hea

t (K

cal/k

g/o C)

w/b = 0.25; r = 0.5 (Test)w/b = 0.40; r = 0.5 (Test)w/b = 0.25; r = 0.5 (Model)w/b = 0.40; r = 0.5 (Model)

hphpfaufacucwfwssgg z)t(nz)t(nz)t(nz)t(nznzn)t(Z +++++=

Z(t) : conductivity of concrete at any time.Zi : conductivity of i-th component of concreteni : volume metric ratio of i-th component of concrete

Thermal Coefficients

Coarse aggregate

(Lime Stone)

Fine aggregate

(Sand)Water Cement Fly Ash Air Hydrated

Product *

Heat Conductivities (Kcal/m.day.C)

20.50 7.50 12.44 0.62 1.16 0.54 23.5

( ) 0chyuc n)t(1)t(n α−=uc

hc

* Back analysis

ASHRAE: American Society of Heat Refrigerating and Air Conditioning Engineering

Thermal Conductivity Model

Thermal Conductivity Test

Thermal conductivity of w25r0. Thermal conductivity of w40r0.

Verification of Thermal Conductivity Model

0

5

10

15

20

25

0 5 10 15 20 25 30

Time (days)

Ther

mal

Con

duct

ivity

(kca

l/m/d

ay/o C)

Test

Model0

5

10

15

20

25

0 5 10 15 20 25 30

Time (days)

Ther

mal

Con

duct

ivity

(kca

l/m/d

ay/o C)

Test

Model


*Temperature Gradient of Concrete*

Temperature of Concrete

Specific Heat

Heat Conductivity

∫ ∆== TsHdtQ ρs : Specific Heatρ : Specific GravityH : Heat Generation rate per unit

volumeT : Temperature of concrete

HzT

yT

xTK

dtdTs +

∂∂

+∂∂

+∂∂

=

2

2

2

2

2

2

ρ

Heat Transfer Coefficient ( ) ( )extTTmnHTk −=+∇− .2

K : Heat conductivityH : Heat generation rate per unit volumen : Outward unit vector normal to the

surfacem : Heat transfer coefficient

Input interface for temperature calculation

Input interface for Input interface for temperature calculationtemperature calculation

Output interface for temperature calculationOutput interface for temperature calculationOutput interface for temperature calculation

Verification by Adiabatic Test Results

Adiabatic temperature rise of Portland cement mixture (Suzuki et al. 1990)

0102030405060708090

100110

0 2 4 6 8

10 (Test)20 (Test)30 (Test)10 (Model)20 (Model)30 (Model) 0

102030405060708090

0 2 4 6 8

10 (Test)20 (Test)30 (Test)10 (Model)20 (Model)30 (Model)

°C°C°C°C°C°C

01020304050607080

0 2 4 6 8


Age of Paste (days)

Tem

pera

ture

(o C)

Age of Paste (days)

Tem

pera

ture

(o C)

Age of Paste (days)

Tem

pera

ture

(o C)

Total binder = 400 kg/m3



°C°C°C°C°C°C

°C°C°C°C°C°C

Verification by Adiabatic Test Results

Adiabatic temperature rise of blend cement mixture with 20 % fly ash replacement (Suzuki et al. 1990)

0

20

40

60

80

100

0 2 4 6 8


0

20

40

60

80

100

0 2 4 6 8


010

20304050

6070

0 2 4 6 8


Age of Paste (days)

Tem

pera

ture

(o C)

Age of Paste (days)

Tem

pera

ture

(o C)

Age of Paste (days)

Tem

pera

ture

(o C)




°C°C°C°C°C°C

°C°C°C°C°C°C

°C°C°C°C°C°C

Verification of the Program

Temperature rise in a footing (38.4×8.4×4.75 m)

0102030405060708090

0 5 10 15 20

Time (Days)

Tem

pera

ture

(o C

)

Test

Model(adiabatic)

(actual)

Autogenous Shrinkage Model

Concrete as a 2Concrete as a 2--Phase MaterialPhase Material

= + =

Concrete Aggregate phase Paste phase Concrete as 2-phase material

na np

εconc εconcεpεa

Paste phase undergoes shrinkage

Aggregate phase resists the shrinkage

Equilibrium Condition

Strain Compatibility

0)pa()ap(i =−σ+−σ=σ∑

concpara ε=ε=ε

474.04 )cf(1005.1pE ××=

concVaV

an =

Model for aggregate restraintModel for aggregate restraint

Model for paste of concreteModel for paste of concrete

Stress-Strain Relationiii E ε×=σ

ap

appoconc EE

)n1(E

+

−⋅⋅ε=ε

Model for Paste ShrinkageModel for Paste Shrinkage((εεp0p0))

CementFly Ash

Principle of Principle of ModellingModelling

)t()t()t( )t( expphy,aschem,asas ε−ε+ε=ε

save

sphy,as E

)t(r)t(A2 )t( ⋅γ

=ε

Capillary Surface Capillary Surface Tension StressTension Stress

( ))t(mE

)t(mD)t(mC

)t(mB )t(mA (t)

FAFA

S2CS2CS3CS3C

AF4CAF4CA3CA3Cchem,as

α⋅⋅+

α⋅⋅+

α⋅⋅+

α⋅⋅+

α⋅⋅=ε

Effect of Types of Cement on Effect of Types of Cement on AutogenousAutogenous Shrinkage of PasteShrinkage of Paste

0

200

400

600

800

1000

1200

1400

0 10 20 30 40 50 60

Age (days)

Aut

ogen

ous

Shrin

kage

(mic

ron)

C3

C1

C5

Type 1

Type 3

Type 5

Effect of Fineness of Cement on Effect of Fineness of Cement on AutogenousAutogenous Shrinkage of PasteShrinkage of Paste

0

300

600

900

1200

1500

1800

0 10 20 30 40 50 60Age (days)

Aut

ogen

ous

Shrin

kage

(mic

ron)

3190

5570

7430 (Blaine)

Effect of Water to Binder Ratio on Effect of Water to Binder Ratio on AutogenousAutogenous Shrinkage of PasteShrinkage of Paste

0

200

400

600

800

1000

1200

1400

0 10 20 30 40 50 60

Age (days)

Aut

ogen

ous

Shrin

kage

(mic

ron) 0.25

0.30

0.40

0

200

400

600

800

1000

0 10 20 30 40 50 60

Age (days)

Aut

ogen

ous

Shrin

kage

(mic

ron)

Effect of Curing Temperature on Effect of Curing Temperature on AutogenousAutogenous Shrinkage of PasteShrinkage of Paste

T = 40

T = 25

Effect of Type of Fly Ash (SOEffect of Type of Fly Ash (SO33 content) on content) on AutogenousAutogenous Shrinkage of PasteShrinkage of Paste

0

200

400

600

800

1000

0 10 20 30 40 50 60

Age (days)

Aut

ogen

ous

Shrin

kage

(mic

ron)

0.15%

1.58%

Effect of Fly Ash Content on Effect of Fly Ash Content on AutogenousAutogenous Shrinkage of PasteShrinkage of Paste

-200

0

200

400

600

800

1000

1200

0 10 20 30 40 50 60

Age (days)

Aut

ogen

ous

Shrin

kage

(mic

ron)

30%

0%

50%

Model for Aggregate RestraintModel for Aggregate Restraint(E(Eaa))

Concept :

Stress is transferred at the aggregate contacts

Density Function For Contact AngleDensity Function For Contact AngleΩ (θ)

θ0 π π4 2

θ

∫π

=θθΩ/2

0

1.0 d)(

)2sin( )( θ=θΩ

θσ⋅µ=θ c f

θω⋅′=θσ cE c

Constitutive Relation for Normal DirectionConstitutive Relation for Normal Direction

25 cmkgf105.2 ×

Stress in Direction Parallel to Contact PlaneStress in Direction Parallel to Contact Plane

contact surface before deformation

ƒθ

Coefficient of Coefficient of Contact Friction of AggregatesContact Friction of AggregatesRegarding Effect of Water LubricationRegarding Effect of Water Lubrication

For Coarse AggregateFor Coarse Aggregate24.0

gSsSwV

15.0SSD,gg

+⋅−µ=µ

For Fine AggregateFor Fine Aggregate24.0

gSsSwV

28.0SSD,ss

+⋅−µ=µ

0.36 for dry crushed limestone 0.31 for dry river sand

0.000.050.100.150.200.250.300.350.40

0.00 0.05 0.10 0.15 0.20 0.25 0.30

Vw/(Ss+Sg)

µ

crushed limestone coarse aggregate

river sand

+

⋅⋅

−−−=α 602.0

cwln497.05.05.0

max,anan

11

2

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0.00 0.20 0.40 0.60 0.80 1.00

na/na,max

α

w/b=0.25

w/b=0.30

w/b=0.40

w/b=0.50

w/b=0.60

w/b=0.70

Effect of Water Content on Effect of Water Content on Aggregate Contact AreaAggregate Contact Area

Model for Aggregate StiffnessModel for Aggregate Stiffness

(Mixtures of Coarse and Fine Aggregates)

Stress Contributed by Each MaterialsStress Contributed by Each Materials

Stress Produced by Coarse AggregateStress Produced by Coarse Aggregate

Stress Produced by Fine AggregateStress Produced by Fine Aggregate

ssgs ).n1( −σ−=σ

σg-gσs-g

σs-s

ssggggsggg .n −−−+− σ+σ=σσ=σ

Total Stress of the Combined AggregatesTotal Stress of the Combined Aggregates

ssggsga −− σ+σ=σ+σ=σ

θ⋅⋅θ⋅+θ⋅σ⋅θΩ=σ ∫π

θθθ dA)sinfcos()( /2

0)g(c)g()g(c)z(a

θ⋅⋅θ⋅+θ⋅σ⋅θΩ+ ∫π

θθθ dA)sinfcos()( /2

0)s(c)s()s(c

θ⋅⋅θ⋅−θ⋅σ⋅θΩ=σ ∫π

θθθ dA)cosfsin()( /2

0)g(c)g()g(c)y(a

θ⋅⋅θ⋅−θ⋅σ⋅θΩ+ ∫π

θθθ dA)cosfsin()( /2

0)s(c)s()s(c

)1())g(cdA)g(ocA( )g(cA ϕ−⋅α⋅φ⋅θ+=θ ∫

Effect of Particle Interference on Contact Area Effect of Particle Interference on Contact Area of Coarse Aggregateof Coarse Aggregate

α⋅φ⋅θ+=θ ∫ ))s(cdA)s(ocA( )s(cA

Particle interference caused by fine aggregate reduces the contact area of coarse aggregate

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.0 0.2 0.4 0.6 0.8 1.0

ns/ns,max

ϕ

ng/ng,max = 0

ng/ng,max = 0.9

ng/ng,max = 0.3

ng/ng,max = 1

ng/ng,max = 0.7

−×

⋅−−+×

⋅=ϕ

⋅

402.5

max,g

g

max,g

g

nn

.0241

max,s

s1-

nn

1 n

n538.8561.0exp429.0

nn15tan

016.0

max,g

g

Test and Analytical Results of Test and Analytical Results of AutogenousAutogenousShrinkage of NoShrinkage of No--Fine ConcreteFine Concrete(Effect of Coarse Aggregate Content)(Effect of Coarse Aggregate Content)

0

100

200

300

400

500

0 10 20 30 40 50 60 70 80 90 100 110

Elapsed Time (days)

Aut

ogen

ous

Shrin

kage

(m

icro

-stra

in)

T est G-40 Test G-60 Test G-80 Test G-100

G-40

G-60G-80G-100

G/Gmax

Test and Analytical Results of Test and Analytical Results of AutogenousAutogenousShrinkage of MortarShrinkage of Mortar

(Effect of Fine Aggregate Content)(Effect of Fine Aggregate Content)

0

100

200

300

400

500

600

700

800

0 10 20 30 40 50 60 70 80

Elapsed Time (days)

Aut

ogen

ous

Shrin

kage

(m

icro

-stra

in)

T est S-40 Test S-50 Test S-60 Test S-70 Test S-85

S-50S-60S-70

S-85

S-40

S/Smax

PERFORMANCE BASED PERFORMANCE BASED PREDICTION MODELPREDICTION MODEL

:Carbonation of Fly Ash Concrete:Carbonation of Fly Ash Concrete

(ii) Flow chart of the model(ii) Flow chart of the model(ii) Flow chart of the model

Input interface for carbonation

Input interface for Input interface for carbonationcarbonation

Output interface for carbonation predictionOutput interface for carbonation predictionOutput interface for carbonation prediction

0

100

200

300

400

1 10 100 1000Ages (day)

CH (k

g/m

3 of

mor

tar)

T est (r=0%)Test (r=20%)Test (r=30%)Model (r=0%)Model (r=20%)Model (r=30%)

(a) w/b = 0.4

0

100

200

300

400

0 20 40 60Replcement percentage (%)

CH (k

g/m

3 of m

orta

r)

T est

Model

(b) w/b = 0.5

0

100

200

300

400

0 20 40 60Replcement percentage (%)

CH (k

g/m

3 of m

orta

r)

T est

Model

CH in mortar specimen (Papadakis’s data)

: w/b = 0.5 and A/B = 3.0

CH in mortar specimen (CH in mortar specimen (PapadakisPapadakis’’ss data)data)

: w/b = 0.5 and A/B = 3.0 : w/b = 0.5 and A/B = 3.0

CH in mortar specimen (Author’s data) at 28 daysCH in mortar specimen (AuthorCH in mortar specimen (Author’’s data) at 28 dayss data) at 28 days

2.5 Verifications2.5 Verifications

(i) Verification of CH (i) Verification of CH (i) Verification of CH

Average CO2 concentration = 650 ppm.Average relative humidity = 70%Average temperature = 29 °C

Average COAverage CO22 concentration = 650 concentration = 650 ppmppm..Average relative humidity = 70%Average relative humidity = 70%Average temperature = 29 Average temperature = 29 °°CC

(ii) Verification of carbonation depth (real environment)

- Carbonation depth was the distance from concrete surface to center of the innermost concrete element that has the pH value less than 9

(ii) Verification of carbonation depth (ii) Verification of carbonation depth (real environment)(real environment)

-- Carbonation depth was the distance from concrete surface to cenCarbonation depth was the distance from concrete surface to center ter of the innermost concrete element that has the pH value less thaof the innermost concrete element that has the pH value less than 9n 9

(a) 6 months

0

5

10

15

20

25

0 20 40 60Replacement of fly ash (%)

Car

bona

tion

dept

h (m

m)

T est (w/b=0.4)Test (w/b=0.5)Test (w/b=0.6)Model (w/b=0.4)Model (w/b=0.5)Model (w/b=0.6)

(b) 12 months

0

5

10

15

20

25


Car

bona

tion

dept

h (m

m)


(c) 18 months

0

5

10

15

20

25


Car

bona

tion

dept

h (m

m)


(iii) Verification of carbonation depth (accelerated environment)(iii) Verification of carbonation depth (iii) Verification of carbonation depth (accelerated environment)(accelerated environment)

0

5

10

15

20

25

30

0 10 20 30 40Replacement of fly ash (%)

Car

bona

tion

dept

h (m

m)

T est (w/b=0.5)Test (w/b=0.6)Model (w/b=0.5)Model (w/b=0.6)

0

10

20

30

40

0 10 20 30 40

Predicted carbonation depth (mm)

Test

carb

onat

ion

dept

h (m

m)

Sulpapha et al. 2003

Atis 2002

Author's

Average CO2 concentration = 4%Average relative humidity = 55%Average temperature = 40 °C

Average COAverage CO22 concentration = 4%concentration = 4%Average relative humidity = 55%Average relative humidity = 55%Average temperature = 40 Average temperature = 40 °°CC

CO2 concentration Sulapha = 6.0 %Atis = 4.7 %Author’s = 4.0 %

COCO22 concentration concentration SulaphaSulapha = 6.0 %= 6.0 %AtisAtis = 4.7 %= 4.7 %AuthorAuthor’’s = 4.0 %s = 4.0 %

3. Mix Design of Concrete Subjecting to Carbonation 3. Mix Design of Concrete 3. Mix Design of Concrete Subjecting to Carbonation Subjecting to Carbonation

0

200

400

600

800

1000

60 70 80 90 100

Relative humidity (%)

CO

2 Con

cent

ratio

n (p

pm)

Proposed Three Zones based on Severity of Environment

Severe

Moderate

Low

Cement only

0

20

40

60

80

100

0.40 0.50 0.60 0.70

water to binder ratio

Cove

r thi

ckne

ss (m

m)

30 years

50 years75 years

100 years

30% FA (2a)

0

20

40

60

80

100

120

0.40 0.50 0.60 0.70

water to binder ratio

Cove

r thi

ckne

ss (m

m)

30 years

50 years75 years

100 years

Design Chart for Severe Environment

PERFORMANCE BASED PERFORMANCE BASED PREDICTION MODELPREDICTION MODEL

:Chloride induced steel corrosion:Chloride induced steel corrosion

Conceptual Service Life Model of Steel in Concrete

Initiation or maintenance free period Propagation

Cor

rosi

on le

vel

Time

Service life

Cracking of concrete

Start of steel corrosion

Limit state

Depassivation time

Corrosion rate

1

Cl-CO2

Steel

Concrete

Simulation ofChloride-Induced Corrosion of Steel in Concrete

Models :• Movement of chloride and water vapor

(Fick’s second law of diffusion)

• Chloride binding capacity

• Carbonation

• Cyclic wetting and drying

• Ion adsorption and surface condensation

• Ion exchange

• Depassivation criteria

Chloride BindingChloride Binding

Chlorides in Concrete

C-S-H from hydration of C3S , C2S

Adsorbed chlorides on the pore walls

Adsorbed chlorides on the surfaceFiner, fine and coarse aggregates

3CaO.Al2O3.CaCl2.10H2O (Calcium Chloroaluminate, Friedel’s Salt)3CaO.Fe2O3.CaCl2.10H2O (Calcium Chloroferrite)

This chloride attacksthe steel

Fixed chlorides Free chlorides

Total chlorides

2. Chlorides physically bound to the surface of hydration and pozzolanic products

By non - reactive materials

By cementitious materials

C-S-H and CAH from pozzolanic reaction

1. Chlorides chemically bound in the structure of hydration products

3. Chlorides physically bound by other hydration products; monosulfate, ettringite, etc.

Absorbed chlorides

CAH and CAFH from hydration of C3A , C4AF

Chloride binding capacity

0.000

0.100

0.200

0.300

0 20 40 60 80 100Difference of degree of hydration during

submersion period (%)

Fixe

d ch

lorid

e ra

tio, λ

C3AC4AF

Relationship between fixed chloride ratios of C3A and C4AF and their degrees of hydration

α∆×

+

=λ

10003 3

3

303

121AC.

AC,fix

e.

.

α∆×

+

=λ

10033 4

4

303

600AFC.

AFC,fix

e.

.

AFCorAC 43α∆ Paste is denser. Less amount of C3A and

C4AF to catch chlorides.(Low fixed chloride ratio)

fix

α∆,

0.26

0.14

Relationship between fixed chloride content of hydrated products and total chloride content

50

572100020 3190010037013500930 .

c

tot

totC).b/w.(fix

F.C

Ce.

.b/w.tot

×

+

×

+

+×−=φ

×−×−

w/b=0.3

0w/b=0.40

w/b=0.50

totC

More amount of chlorides in pore.

More fixed chloride content

0.00

1.00

2.00

3.00

4.00

0.00 1.00 2.00 3.00 4.00

Total chloride content, Ctot

(% by wt of binder)

Fix

ed c

hlor

ide

cont

ent o

f hyd

rate

d pr

oduc

t, φ

fix (%

)Data of w/b=0.30Data of w/b=0.40Data of w/b=0.50Model of w/b=0.30Model of w/b=0.40Model of w/b=0.50

∑×φ=− )t(MFixCl eproductsfixbindingphysicalby

Program of Chloride Binding Capacity

Calculation:

Total Cl- = [Ci ]- [Cf ] * V

Free Cl- is known from Expressed Pore Solution

So, Fixed Cl- = Total Cl- - Free Cl-

Chloride binding capacity = Fixed Cl- / Total Cl-

Final Cl- concentration, [Cf], ppM

End of submersion at time T

Initial Cl- concentration, [Ci ], ppM

Experimental Setup of Chloride Binding CapacityStart of submersion at time Ts

Disk specimens

Saltwater, volume V

Mix Designation

End of submersion,Date of expression

Curing period

Submersion period

Date of casting Start of submersion

Time (days)

Cement pasteC1: Type I cement, w/c=0.30 C2: Type I cement, w/c=0.40C3: Type I cement, w/c=0.50C4: Type III cement, w/c=0.40C5: Type V cement, w/c=0.40

Cement - fly ash pasteCement+Fly Ash A (Low calcium)FA1: Type I cement + Fly ash A (30%), w/c=0.40 FA2: Type I cement + Fly ash A (50%), w/c=0.40 FA3: Type I cement + Fly ash A (70%),w/c=0.40Cement+Fly Ash B (High calcium)

FB1: Type I cement + Fly ash B (30%), w/c=0.40 FB2: Type I cement + Fly ash B (50%), w/c=0.40 FB3: Type I cement + Fly ash B (70%), w/c=0.40

Curing and submersion period

Curing period: 1, 7 and 28 day Submersion period: 28, 56 and 91 day

Ts T

Experiment Details

Measurement of [OH-]by pH meter

Measurement of [Cl-] by potentiometrictitration with AgNo3 solution and chloride ion selective electrode

Pore-expressed method3.00 % of Cl- for saltwater

(External Chlorides)

Model of Chloride Binding Capacity of Fine Aggregate and Finer Aggregate

0.000

0.002

0.004

0.006

0.008

0.010

0 1,000 2,000 3,000 4,000 5,000

Fix chloride ratio, φfix, (by weight)

Specific surface area, S (cm2/g)

Sand

LS2 LS3LS1

0.54745fix )S(106 −×=φ

From Plangngeon and Tangtermsiriul

0.00

1.00

2.00

0.00 1.00 2.00

CFL1CFL2CFL3CFH1CFH2CFH3

Verification of CBC Model (External Chlorides)

ts = 1, 7, 28 daysAge at start of submersion:

Submersion period: te-ts = 28, 56, 91 days

Sumranwanich et.al.

Cfix (% by wt of binder) from modelCfix (% by wt of cement) from model

Cfix (% by wt of binder) from experimentCfix (% by wt of cement) from experiment

Cement paste Cement-fly ash paste

0.00

1.00

2.00

0.00 1.00 2.00

C1C2C3C4C5

Verification of CBC Model (External Chlorides)

0.00

1.00

2.00

3.00

0.00 1.00 2.00 3.00

cement mortarfly-ash mortarconcrete

ts = 28 days

Age at start of submersion:

Submersion period:te-ts = 28, 91, 182, 365 days

Maruya et. al.

Cfix (% by wt of binder) from model

Cfix (% by wt of binder) from experiment

Mortar and concrete

0.00

1.00

2.00

0.00 1.00 2.00

cement paste

Cfix (% by wt of cement) from model

Cfix (% by wt of cement) from experiment

Cement pasteArya et. al.

ts = 2, 28, 84 daysAge at start of submersion:

Submersion period:te-ts = 28, 56, 84 days

Chloride Diffusion CoefficientChloride Diffusion Coefficient

0.0000

0.0040

0.0080

0.0120

0.0160

0 200 400 600

mortar (sur)mortar (inn)fly ash mortar (sur)fly ash mortar (inn)model: mortar (sur)model: mortar (inn)model: fly ash mortar (sur)model: fly ash mortar (inn)

Model of Time-Dependent Chloride Diffusion Coefficient)day/cm(),t(D 2

CL

5.3100

)t(n1.2ave )()t(d200 ××

For surface element;

For inner element;

Cl-

Surface element

Inner elements

Maruya and Tangtermsirikul

( )

×××−

+

= 5.35.1

ave 100)t(n)t(d2000197.0

CL

e00043.0

000012.0t,1D

+

××+× 1

bf25.0)375.0R( 3

p

×

100)t,1(CW

×

100)t,x(CW

+

××+× 1

bf25.0)375.0R( 3

p( )

×××−

+

= 5.35.1

ave 100)t(n)t(d2000184.0

CL

e00039.0

000010.0t,xD

Pore StructuresPore Structures(Average pore diameter and Total porosity)(Average pore diameter and Total porosity)

Average Pore Diameter of Paste

nm),t(dave

%),t(aveα

Effect of water to cement ratio

Effect of type of cement

nm),t(dave

%),t(aveα0

20

40

60

80

100

50 60 70 80 90 100

data: w/c=0.30data: w/c=0.40model: w/c=0.30model: w/c=0.40

0

10

20

30

40

50

50 60 70 80 90 100

data: type Idata: type IIIdata: type Vmodel: type Imodel: type IIImodel: type V

Average Pore Diameter of Paste (continued)

nm),t(dave

%),t(aveα

Effect of fly ash

Model of average pore diameter, dave(t)

( )( )( ) ( )( ) ( )

α

×+−×−++−×= 100

t92.019.0b/w5.645.219.0b/w2.8

ave

ave56.078.0

etd

−

×

−

21.0100

AC 065.03

+× 57.0

F1602

02.1c

+

×−×

−× 45.1

bf68.0

bf1

+

α×−× 2

100)t(

5.1 ave

0

10

20

30

40

50

0 20 40 60 80 100

data: f/b=0data: f/b=0.30data: f/b=0.50data: f/b=0.70model: f/b=0model: f/b=0.30model: f/b=0.50model: f/b=0.70

Total Porosity of PasteEffect of water to cement ratio

Effect of type of cement

%),t(n

%),t(aveα

%),t(n

%),t(aveα10

20

30

40

50

40 60 80 100

data: type Idata: type IIIdata: type Vmodel: type Imodel: type IIImodel: type V

0

10

20

30

40

50

50 60 70 80 90 100

data: w/c=0.30data: w/c=0.40model: w/c=0.30model: w/c=0.40

Total Porosity of Paste (continued)

Effect of fly ash

Model of total porosity, n(t)

%),t(n

%),t(aveα

( )

+

×= 4.77

bwln9.23tn

( )( ) ( )100

t2.1b/w86.0 ave43.1

e5.26

6.27α

×+× −

+×

−

×

−

21.0100

AC 065.03

+× 57.0

F1602

02.1c

+

×−× 1

bf25.0

5.0

0

10

20

30

40

50

40 60 80 100

data: f/b=0data: f/b=0.30data: f/b=0.50data: f/b=0.70model: f/b=0model: f/b=0.30model: f/b=0.50model: f/b=0.70

Chloride condensation in Chloride condensation in submerged zonesubmerged zone

Chloride Condensation in Surface LayerSurface layer Internal layers

Environment Cl-

concentration

Cl- concentration distribution

Surface Cl-concentration

Environment Cl-

concentrationSurface Cl-concentration

Environment

Surface layer Internal layersEnvironment

adsorption

>

<

Cl- concentration distributionadsorption

diffusion

diffusion ClCl--

ClCl--

ClCl--

ClCl--

Model of Time-Dependent Ion Adsorption

)t,1(Fad = Ion adsorption flux of surface element, mol/(cm2/day)

)t,1(Fad

)t,1(C B,f

where,

= Free chloride content of surface element, % by wt of binder)t,1(C B,f

Cl-

Cl-Cl-Cl-

Cl-

Cl-

Cl-Cl- Cl-

Solid phase

Liquid phase

Solid phase

Cl-

Cl- Cl-free chloride fixed chloride

( ) ( ) ( ) )t,1(C5.0b,f

05.0p

443.0ad

b,fe100

)t(n1)t,1(C35.0RB0000034.0t,1F −××+×−×××=

Rp = Paste ratio

n(t) = Porosity, %

B = Binder content (kg/m3)

Chloride condensation due to Chloride condensation due to CarbonationCarbonation

Effect of Carbonation

Non-carbonation zone

Carbonation zone

Air(CO2)


Environment Cl- concentration

diffusion

Free chloride increases

Total chloride reduces

Chloride condensation due to Chloride condensation due to effect of wetting & dryingeffect of wetting & drying

Effect of Cyclic Wetting and Drying

Wetting period, Twet

Drying period, Tdry

Pore solution

Environment Cl- concentration


Surface layer Internal layersEnvironment

Pore

Pore

Air

WaterWaterEvaporation

SaltwaterSaltwater

Capillary suction

Ion EquilibriumIon Equilibrium

0.00

0.50

1.00

0.00 5.00 10.00

[Cl-]/[OH-]

Hyd

roxy

l exc

hang

e ra

te, ψ

Mechanism of Ion Exchange

Steel

OH -Cl-

K+

Na+SO42-

Concrete

Cl- Cl- Cl-

OH- OH- OH-

Cl-Cl-

OH -OH -K+

K+

SO42- SO4

2-

SteelSteel

OH -Cl-

K+

Na+SO42-

Concrete

Cl- Cl- Cl-

OH-SO42

-

Cl-Cl-

OH -OH -K+

K+

SO42- SO4

2-

SO42

-

0.1=ψ

[ ] [ ][ ] 473.0OH/Cl235.0 −−−×=ψ

17.0=ψ

DepassivationDepassivation CriteriaCriteria

Depassivation Criteria

1. Chloride corrosion threshold• Depend on the hydroxyl concentration in pore solution• [Cl-]cr = 0.1716 [OH-] 0.7619

where, [Cl-]cr = critical chloride concentration, mol/l[OH-] = hydroxyl concentration, mol/l

2. Adequate water supplied• Optimum relative humidity is 70-80%

3. Oxygen provided

Chloride Threshold for Corrosion

0.00

0.04

0.08

0.12

0.00 0.20 0.40 0.60 0.80

[OH-] (mol/l)

[Cl-] c

r (mol/

l)

Input interface for calculation of chloride distribution (I)Input interface for calculation of chloride distribution (I)Input interface for calculation of chloride distribution (I)

Input interface for calculation of chloride distribution (II)

Input interface for calculation of Input interface for calculation of chloride distribution (II)chloride distribution (II)

Simulation of Chloride Profile of Cement-Fly Ash Mortar(Internal chloride)

Maruya and Tangtermsirikul:(Dissolving Test)cement-fly ash mortar,w/b = 0.50, f/b = 0.20ts = 28 days

Cl-

[Cl-] = 0.94 % by wt of binder

0.00

0.50

1.00

1.50

2.00

0.0 1.0 2.0 3.0 4.0 5.0 6.0

Distance from surface (cm)

Chl

orid

e co

nten

t (%

by

wt o

f cem

ent) total (model)

free (model)total (test)free (test)

0.00

0.50

1.00

1.50

2.00

0.0 1.0 2.0 3.0 4.0 5.0 6.0


Chl

orid

e co

nten

t (%

by

wt o

f cem

ent) total (model)


0.00

0.50

1.00

1.50

2.00

0.0 1.0 2.0 3.0 4.0 5.0 6.0


Chl

orid

e co

nten

t (%

by

wt o

f cem

ent) total (model)


Simulation of Chloride Penetration in Concrete (External chloride)

Maruya and Tangtermsirikul:concrete,w/c = 0.50ts = 28 days

Cl-

[Cl-] = 1.82 % of Cl-

0.00

1.00

2.00

3.00

4.00

5.00

0.0 1.0 2.0 3.0 4.0 5.0 6.0Distance from surface (cm)

Chl

orid

e co

nten

t (%

by

wt o

f cem

ent)

total (model)free (model)total (test)free (test)

0.00

1.00

2.00

3.00

4.00

5.00


Chl

orid

e co

nten

t (%

by

wt o

f cem

ent)


0.00

1.00

2.00

3.00

4.00

5.00


Chl

orid

e co

nten

t (%

by

wt o

f cem

ent)


0.00

1.00

2.00

3.00

4.00

5.00


Chl

orid

e co

nten

t (%

by

wt o

f cem

ent)


Submersion period = 28 days Submersion period = 91 days Submersion period = 182 days

Submersion period = 365 days

Effect of water to cement ratio on depassivation time

0

200

400

600

800

1,000

0.20 0.30 0.40 0.50 0.60 0.70

Water cement ratio

Dep

assi

vatio

n tim

e (d

ay)

Cement paste:Ts = 28 day

Twet = 7 day, Tdry = 7 day[Cl-] of saltwater = 0.085 mol/l

Effect of saltwater concentration on depassivation time

0

200

400

600

800

1,000

0 2 4 6Chloride concentration of saltwater (x10,000 ppM)

Dep

assi

vatio

n tim

e (d

ay)

Cement paste:Ts = 28 day

Twet = 7 day, Tdry = 7 day

Effect of depth of concrete cover on depassivation time

0

200

400

600

800

1,000

2 3 4 5 6 7 8

Depth of concrete cover (cm)

Dep

assi

vatio

n tim

e (d

ay)

Depassivation time of different environment

766

512

0

200

400

600

800

1000

1 2


Dep

assi

vatio

n tim

e (d

ay)

Subemerged in saltwater

Subemerged in saltwater &Cyclic wetting and dryingTwet = 7 day, Tdry = 7 day

[Cl-] of saltwater =0.845 mol/lw/c = 0.40

Ts = 28 day

Durability of Fly Ash Concrete under Durability of Fly Ash Concrete under Sulfate AttackSulfate Attack

Sulfate AttackSulfate Attack

CH+NS+2H CSH2 + NH (1)C4AH13+3CSH2 +14H C6AS3H32 + CH (2)C4ASH12+ 2CSH2+16H C6AS3H32 (3) C3A+3CSH2+26H C6AS3H32 (4)

1. Mechanisms of NS Attack

Sulfate AttackSulfate Attack

CH+MS+2H CSH2+MH (5)CxSyHz+ xMS+(3x+0.5y-z)H

xCSH2 + xMH+0.5yS2H (6)4MH+SH11 M4SH8.5+(n-4.5)H (7)

2. Mechanisms of MS Attack

Appropriate percent replacement of fly ash in sulfate environment

NS, Expansion

NS, Type I

0 0

0

35

00

-40

-20

0

20

40

60

80

0.40 0.45 0.50 0.55 0.60

Water to binder ratio

Perc

ent r

epla

cem

ent o

f fly

ash

, %

8.28% CaO,1.04% SO3 FA17.28% CaO,2.01% SO3 FA14.65% CaO,6.50% SO3 FA

Above the line: Better than Type I

Beneath the line: Poorer than Type I

NS, Type V

00

40

00

0

-40

-20

0

20

40

60

80

0.40 0.45 0.50 0.55 0.60Water to binder ratio

Perc

ent r

epla

cem

ent o

f fly

ash

, %

8.28% CaO,1.04% SO3 FA17.28% CaO,2.01% SO3 FA14.65% CaO,6.50% SO3 FA

Above the line: Better than Type 5

Beneath the line: Poorer than Type 5

Conclusion

To obtain durable structures • For New Construction

– Good Analysis and Design (new PWCP design acts)

– Good Materials (new TCA material spec.)– Good Construction (?)– Good Protection and Maintenance

• For Already Existing Structures*– Monitoring, Protection, Maintenance,

Repair, Strengthening

The End

Thank you for your attention

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