2010 International Concrete Sustainability Conference, Dubai, UAE 1 American University in Dubai A School of Engineering Infrastructure Sustainability and Assessment Center Evaluation of Service Life of Reinforced Concrete Structures in the Middle East By MEDRC
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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
2010 International Concrete Sustainability Conference, Dubai, UAE 2
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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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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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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