2010 International Concrete Sustainability Conference, Dubai, UAE 1
American University in DubaiyA School of Engineering
Infrastructure Sustainability and
Assessment CenterEvaluation of Service Life of Reinforced Concrete
Structures in the Middle East
By
MEDRC
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What is DurabilityDurability by definition is the ability of concrete to resist weathering action, chemical attack, and
b i hil i t i i it d i d i iabrasion while maintaining its desired engineering properties
C t i di t ti d i t tiConcrete ingredients, proportions and interaction
Placement and curing
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Concrete Sustainability and Durability• Concrete is Durable Construction Material
• Enhancing Concrete Durability• Use of Supplementary Cementing Materials (SCM)
• Extend the Structure Service Life
• Minimize maintenance
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Construction in the Middle EastFirst Generation of Construction (1970’s)
Foreign codesIgnorance of the unique environment of the regionPoor quality concreteSevere deterioration
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Concrete Durability ParametersAlkali Silica Reactivity (ASR)
Delayed Ettringite FormationDelayed Ettringite Formation
Sulphate Attack
Corrosion of reinforcing steel
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Alkali Silica ReactivityThis is caused by reaction of certain aggregates with alkali in cement to form expansive gel that eventually leads to craking
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Delayed Ettringite Formation
DEF is mainly associated with steam cured precast members.
Curing temperature higher than 70º C leads to formation of DEF cracking.to formation of DEF cracking.
Thermal effects (mass concrete)
Use of SCM
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Sulphate AttackA reaction between sulphate ions and calcium hydroxide and form gypsum and ettringite.
BRE and ACI 201 Classification in UAEBRE and ACI 201 Classification in UAE
Low w/c ration and use of SCM
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Long-Term Sulfate Attack Study (PCA)
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Corrosion
What is CorrosionDeterioration of a material as a result of reaction with its environment-M.G. Fontana
Destructive attack of a metal by chemical or electrochemical reaction with its environment-H.H. Uhling.
Metal corrode because they have a strong driving force to return to their natural state
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Requirements for Corrosion
Cathode
AnodeAnode
Electrolyte
Electrical connection between anode and cathode
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Corrosion of Steel in Concrete
Cathode and anode sites co-exist on the Steel
The steel is the conductor andThe steel is the conductor, and
Concrete acts as electrolyte
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Industrial Structures
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Marine Structures
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Corrosion damage on reinforced concrete bridge structures
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Corrosion damage and catastrophic failure in parking garages
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Why Should We Care About CorrosionWhy Should we Care about Corrosion
Safety
Conservation of Resources
Cost
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Cost of Corrosion
1995 report: • $300 Billion/yr (4.2% of the GNP)
2002 NACE Report:2002 NACE Report:• $276 Billion/yr (3.1% of the GNP)
Utilities 35%Transportation 22%pInfrastructure 16%Government 15%Production & Mfg. 13%
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Cost of Corrosion in the GCC States-20042004
Kingdom of Bahrain 0.5 B.
State of Kuwait 2.17 B.
Sultanate of Oman 1.3 B.
State of Qatar 1.1 B.State of Qatar 1.1 B.
Kingdom of Saudi Arabia 13.0 B.
U it d A b E i t 3 7 BUnited Arab Emirates 3.7 B.
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Why Should We Care About Corrosion
Middle East Durability Research Consortium
PProgram
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Service Life
Hundred-Year Service Life
Requirement in the Region
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Service Life
Service LifeThe period of time during which a structure meets or exceeds the minimum requirements set for it
Requirements limitation can be technical, functional or economical
DurabilityDurability
ASRSulfate attackCorrosion
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Kyösti TuuttiKyösti Tuutti´́s Service Life s Service Life ModelModelModelModelLoss of cross-section
End of S i Lif
LimitService Life
Corrosion Rate(µm/year)
Low-quality“covercrete”
High-quality“covercrete”
Time
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DC/dt = D. d2C/dx2
C Chloride contentC Chloride content
T time
X depth (from exposed surface)
D apparent diffusion coefficient
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Diffusion
Surface Concentration
Concentration Profile Time = t
Depth, X
Courtesy: N. Carino
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FickFick´́s Second Law Solutions Second Law Solution
C x, tx, t = C= Cs s –– ((CCss-- CCii) x ERFC (x/sqrt (Dt)) x ERFC (x/sqrt (Dt)
C h hl id i d h d iCx,t = the chloride concentration at concrete depth x and time tCs = the chloride concentration at the surface, Ci = the initial chloride concentration, D the apparent chloride diffusion coefficient (m2 2D = the apparent chloride diffusion coefficient (m2
/sec, in.2
/year), and ERFC is an error function
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Chloride Diffusion Analysis
Cl- Diffusion Coefficient PredictionResults
0.1
0.12
0.14
0.16
ncre
te)
D = m2/sCs = %Co = %
Max Cover C
Min Cover
Mean Cover0.130.02
6.10E-13
Results
0.02
0.04
0.06
0.08
Cl- (%
by
wt.
con
Threshold Cl-
Measured Data
Prediction when Corrosion initiated
0
0.02
0 10 20 30 40 50 60 70 80 90 100
Depth (mm)
Samples Best Fit
Fitted curve
x )n
ooca
snx
)tt.(.tD2
xerf(1CC −=
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Service Life
Hundred-Year Service Life
How to achieve it???
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How to Achieve it
Concrete Mix Design
Use of corrosion inhibitor and other corrosionUse of corrosion inhibitor and other corrosion preventive methods.
Construction practiceConstruction practiceCuring, surface protection, curing temperature
QA/QC proceduresQ Q p
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How to Achieve it,cont.
For Deep tunnels (inner tunnel) use of in-situFor Deep tunnels (inner tunnel), use of in-situ concrete liner and HDPE liner
Closed Monitoring of Design ParametersClosed Monitoring of Design ParametersCrack limitsConcrete cover
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MEDRC Experimental Program Selected Concrete Mix Design.
Laboratory TestsLaboratory Tests
Service Life Prediction
Field Testing Stations
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Selected Mix Designs
Mix Des. Mix 1 Mix 2 Mix 3 Mix 4 Mix 5 Mix 6OPC 400 400 400 400 136SRC 400GGBS 264MSMS
Fly Ash
TotalCement
400 400 400 400 400 400Cement
Water 200 200 200 160 160 160w/c 0.50 0.5 0.5 0.4 0.4 0.4
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Selected Mix Designs, cont.Mix Des. Mix 7 Mix 8 Mix 9 Mix
10Mix 11
OPC 400 400 400 400 136OPC 400 400 400 400 136SRC
GGBS 264 264MS 32 20 20Fly Ash 120 120 80Total 400 400 400 400 400TotalCement
400 400 400 400 400
Water 160 160 160 160 160w/c 0 40 0 4 0 4 0 4 0 4w/c 0.40 0.4 0.4 0.4 0.4
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Concrete Mixing
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Concrete Mixing
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Laboratory Testing ProgramStandard Durability tests.
ASTM G 109 Testing ProgramASTM G 109 Testing Program
Service Life Monitoring Parameters
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Standard Durability Tests
• Water Permeability, BS EN 12390/DIN 1048
• Water Absorption BS 1881-122Water Absorption, BS 1881-122
• Rapid Chloride Penetration, ASTM C 1202
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RCPT
R id Chl id bilit T tRapid Chloride permeability Test
An Acceptance Test???An Acceptance Test???
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ASTM G 109 Test
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ASTM G 109 Test
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ASTM G 109 Specimens
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Specimen Preparation
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Specimens Preparation
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Specimens Preparation
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Specimens Preparation
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ASTM G 109 Specimens
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ASTM G 109 Specimens
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Service Life Prediction Parameters
• Chloride Migration Coefficient Test NT Build 492
• Diffusion Coefficient Test NT Build 443Diffusion Coefficient Test NT Build 443
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Chloride Migration Coefficient NT 492
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Chloride Migration Coefficient NT 492
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NT Build 443 Diffusion Coefficient
• Coating specimens
• Immersion in salt solution for 35 daysImmersion in salt solution for 35 days
• Use grinded powder samples for chloride measurement and developing chloride profilemeasurement and developing chloride profile
• Curve-fitting chloride profile to Fick’s second law.
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Field Testing Stations
• Selected Concrete mixes
• Relatively large-scale specimensRelatively large-scale specimens
• Long-term marine exposure
• Corrosion activity monitoring
• Correlation with Laboratory finding
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Selected Sites
• The selected sites cover most of the ME marine exposure conditions
• Arabian Gulf exposure (Dubai)
• Dead Sea• Dead Sea
• Mediterranean Sea
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Progress Test Results
• Chloride Permeability
• Chloride Migration Coefficient-NT Build 492Chloride Migration Coefficient-NT Build 492
• Diffusion Coefficient-NT Build 443
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RCP Test Results
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Migration Coef. Vs. Diffusion Coef.
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What Is A Durability Assurance Plan ?
A management process which gives an Asset Owner confidence that the asset under construction will achieve its design life
A f l h i f ll i i hA formal mechanism for all parties in the construction process to maximize delivery of
d bl t ta durable structure
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Why Durability Assessment Planning ?
Match the design with the environmentalMatch the design with the environmental conditions, service life, construction techniques and maintenance requirements
Optimise the process of resource distribution (i.e. money, materials & time)
Provides conduit between design, construction & maintenance during service life
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ConclusionsArabian Peninsula and Gulf region is most corrosive location in the world
Corrosion is the main durability factor leads toCorrosion is the main durability factor leads to deterioration of concrete structures
Use of Quality Concrete and corrosion protection systems such as corrosion inhibitors is the key tosystems such as corrosion inhibitors is the key to achieve the required service life
MEDRC focuses on assessing and optimizing the service life of RC structures in the Middle Eastservice life of RC structures in the Middle East
This study will provide tools to the construction community in the region to achieve long lasting
tconcrete.
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Thank youشڪرًا
Questions?