Post on 04-Sep-2018
transcript
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
Environmental condition
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
Comparison between the predicted and tested slump of concrete
containing various type of powder
Comparison between the predicted and tested slump of concrete
containing various type of fly ash
Comparison between the predicted and tested slump of concrete
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%
Predicted Strength (MPa)
0
10
20
30
40
50
60
0 10 20 30 40 50 60Tested Strength (MPa)
-15%
+15%
Predicted Strength (MPa)
0
10
20
30
40
50
60
0 10 20 30 40 50 60Tested Strength (MPa)
-15%
+15%
Predicted Strength (MPa)
0
10
20
30
40
50
60
0 10 20 30 40 50 60Tested Strength (MPa)
-15%
+15%
Predicted Strength (MPa)
0
10
20
30
40
50
60
0 10 20 30 40 50 60Tested Strength (MPa)
+15%
-15%
Predicted Strength (MPa)
0
10
20
30
40
50
60
0 10 20 30 40 50 60Tested Strength (MPa)
+15%
-15%
Verifications for Conventional Concretes ModelVerifications for Conventional Concretes Model
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)
Predicted Strength (MPa)
0
10
20
30
40
50
60
0 10 20 30 40 50 60Tested Strength (MPa)
with classified fly ashwith ground fly ash
-15%
+15%
Predicted Strength (MPa)
0
10
20
30
40
50
60
0 10 20 30 40 50 60Tested Strength (MPa)
with classified fly ashwith ground fly ash
-15%
+15%
Verifications for Conventional Concretes ModelVerifications for Conventional Concretes Model
Air Entrained ConcreteAir Entrained Concrete High LOI Fly Ash ConcreteHigh LOI Fly Ash Concrete
+15%
-15%
+15%
-15%
Predicted Strength (MPa)
0
10
20
30
40
50
60
0 10 20 30 40 50 60Tested Strength (MPa)
LOI = 0.17%LOI = 4.50%LOI = 5.48%
Predicted Strength (MPa)
0
10
20
30
40
50
60
0 10 20 30 40 50 60Tested Strength (MPa)
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
Predicted Strength (MPa)
0
10
20
30
40
50
0 10 20 30 40 50Tested Strength (MPa)
with original fly ashwith ground fly ashwith air -classified fly ash
+15%
-15%
+15%
-15%
91 Days91 Days 180 Days180 Days
Predicted Strength (MPa)
0
1020
30
40
5060
70
80
0 10 20 30 40 50 60 70 80Tested Strength (MPa)
with original fly ashwith ground fly ashwith air -classified fly ash
Predicted Strength (MPa)
0102030405060708090
100
0 20 40 60 80 100Tested Strength (MPa)
with original fly ashwith ground fly ashwith air -classified fly ash
+15%
-15%
+15%
-15%
Verifications for the Strength Development ModelVerifications for the Strength Development ModelVerifications for the Strength Development Model
365 Days365 Days
Predicted Strength (MPa)
0
20
40
60
80
100
0 20 40 60 80 100Tested Strength (MPa)
with original fly ashwith ground fly ashwith air -classified fly ash
+15%
-15%
Verifications for the Strength Development ModelVerifications for the Strength Development ModelVerifications for the Strength Development Model
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
Total Heat Generation of Concrete
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
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
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
10 (Test)20 (Test)30 (Test)10 (Model)20 (Model)30 (Model)
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
Total binder = 200 kg/m3
Total binder = 300 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
10 (Test)20 (Test)30 (Test)10 (Model)20 (Model)30 (Model)
0
20
40
60
80
100
0 2 4 6 8
10 (Test)20 (Test)30 (Test)10 (Model)20 (Model)30 (Model)
010
20304050
6070
0 2 4 6 8
10 (Test)20 (Test)30 (Test)10 (Model)20 (Model)30 (Model)
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
Total binder = 200 kg/m3
Total binder = 300 kg/m3
°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
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)
(c) 18 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)
(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)
Cl- concentration distribution
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
Cl- concentration distribution
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
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
Distance from surface (cm)
Chl
orid
e co
nten
t (%
by
wt o
f cem
ent) total (model)
free (model)total (test)free (test)
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
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
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
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)
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
Environmental condition
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