High durable concrete

1. 제3장
High Durability Concrete
(고내구성 콘크리트)
Presenter: Bibek Tamang
Student No.: 201715022
Kangwon National University
Reference:
• Advanced Concrete Engineering for Special Uses
(특수콘크리트공학)
• 한국콭크리트학회 편
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2. 3.1 Outline (개요)
• Concrete is the most economical and
durable material used in structures.
• Average life of concrete: 60yrs
• But, it may be reduced due to:
1. quality control in site.
2. Exposure to severe environment.
• Change in design concept of concrete,
demanding high age of concrete structures.
• So high durable concrete is needed.
• Explains how to increase
durability of concrete from 60
years to at least 100 years (with
minimum compressive strength of
600MPa) without any special
repair.
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3. 3.2 Durability Design Techniques
of Concrete Structures
(콘크리트 구조물의 내구성 설계 기법)
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4. 3.2.1 Durability Design
Specifications (시방 규정형 내구성 설계)
• Planning design period of RC structures
without affecting any durability aspect
within that period.
• Design and construction with the aim of
securing durability against deterioration
factors.
• Without require of unexpected large-scale
repairs.
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5. 3.2.1 Durability Design
Specifications
1. Durability Design Goal Setting (내구설게 목표 설정)
• Setting planned design life & deterioration level
that is not allowed within that period.
• Deterioration degree 5 should not be exceeded in
RC structures , as shown in Table.
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6. 3.2.1 Durability Design
Specifications
2. Setting Planned Durable Years
(계획 내용년수 설정)
• Under normal conditions of use and
environmental conditions, the classification
of the durable years of buildings shall be
Class I or Class II.
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7. 3.2.1 Durability Design
Specifications
3. Deterioration phenomenon (열화현상)
• Causes decrease in structural strength.
• Tolerance level in Ductile Design:
 Corrosion of reinforcing steel begins or when
corrosion crack starts to occur in concrete
(corrosion loss is about 5%).
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8. 3.2.1 Durability Design
Specifications
4. Deterioration External Forces (열화외력)
• Climatic factors, Neutralization
• Neutralization is a common factor seen in
specific areas like saltwater.
• Climatic Classification:
• Warm Zone, Cold Zone, Sub-tropical Zone
• Characterized by heat, temperature
change, humidity, rainfall.
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9. 3.2.1 Durability Design
Specifications
5. Adjusting Durable Years (내용년수 조정)
• For safe and comfortable use during
planned period,
• Short-term repair plan
[Service Life coordination to modular
coordination].
• Long-term repair plan
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10. 3.2.1 Durability Design
Specifications
6. Standard for design and construction specification
(설게，시공 시방 표준)
• Using durability design corresponding to the standard
of planned durable year and basic deterioration
external factors.
• Standard Specification for Reinforced Concrete
Construction (JASS 5)
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11. 3.2.2 Durability Design using model
(모델을 사용한 내구성 설계)
• Durability Design Procedure (JCI).pdf
• An example:
• Durability Design Procedure (Example).pdf
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12. 3.3 Required Performance and Mixing
Design of High Durability Concrete
(고내구성 콘크리트의 요구 성능과 배합설계)
3.3.1 High Strength (고강도)
• Pore size is to be reduced and for this w/c ratio is
to be reduced.
• a high-performance AE water reducing agent
capable of achieving a compressive strength of
100 MPa or more and having good workability has
been developed.
• To reduce pore size: Use of admixture having
particle size different than cement.
• Ultra-fine particles: sp. area of 200,000 cm2/g.
• High strength Aggregate
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13. 3.3 Required Performance and Mixing
Design of High Durability Concrete
3.3.2 High Durability (고개구성)
• Is characterized by:
1. Uniform concrete without defects
2. Densified structure and resistance
against penetration of deteriorating
factors.
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14. 3.3.2 High Durability (고개구성)
1. Crack Control (균열 억제)
• Since high durability concrete has a large amount of
cement, there is a great risk of cracking due to
temperature cracks or alkali-aggregate reaction due to
cement hydration heat.
• To reduce cracking, reduce adiabatic temperature,
select powder containing cement.
• For this, use low heat or medium heat Portland cement
having low hydration heat.
• Admixture like fly ash, blast furnace slag, limestone
fine powder is used.
• Use of low-alkali Portland cement with alkali amount <
3 kg/m3
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15. 3.3.2 High Durability (고내구성)
2. Protection of Reinforcement (강재의 보호)
• Reduction of protection: Carbonation &
destruction of passive film.
• Chloride ion: supplied from external
environment, or materials used (cement,
aggregate, admixture, water).
• High Durable Concrete has low carbonation
process and can suppress Chloride ion
penetration.
• Chloride ions content < 0.21 kg / m3 for high
durable concrete.
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16. 3.3.2 High Durability (고구내성)
3. Anti-freezing Property (내동해성)
• High durable should have good anti-
freezing property and relative dynamic
stiffness should be more than 100% even
after completion of 300 cycles of Freezing-
Thawing Resistance test.
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17. 3.3.3 Self-filling property
(자기충진성)
• Requires high fluidity and material separation
resistance simultaneously for self-refilling.
• For self-refilling, amount of powder, or
viscosity agent, or both should be increased.
• Select cement with high fluidity & for this
cobaltite cements with low C3A or C3AF
amount or low heat Portland cement is used.
• Belite Cement with large specific area, high
flow and high-strength is also used.
• Admixture like Silica product to improve
fluidity is also used.
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18. 3.3.4 Mixing of High Durability
Concrete (고내구성 콘크리트의 배합)
• Materials similar to high strength concrete.
• Highly soluble pozzolan materials to reduce
hydration heat, improving compactness of
hardened cement, improving fluidity.
• to reduce the amount of unit cement:
FA (Fly ash), BS (Blast furnace slag fine powder),
BSS (blast furnace slag ultra-fine powder) and SF
(silica ware) are used.
• Absolute volume of coarse aggregate:
0.28 ~0.33 m3/m3 to obtain self -filling property.
Water content < 40%
Min. air amount = 3 ~ 4%.
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19. 3.4 Durability Performance Evaluation
of High Durability Concrete
(고내구성 콘크리트의 내구성능 평가)
3.4.1 Carbonation Resistance
• better resistance to carbonation than
ordinary concrete.
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20. 3.4 Durability Performance Evaluation
of High Durability Concrete
3.4.2 Salt Penetration Resistance (염분짐투 저항성)
If tolerance salt content
(염분함유량의 허용한도) =
1.2 kg/m3,
Age of HDC = 120 ~ 240
yrs.
Age of OC = 60 yrs.
i.e. 2 ~ 4 times more.
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21. 3.4 Durability Performance Evaluation
of High Durability Concrete
• 3.4.3 Freeze-thaw resistance (동결융해 저항성)
• AIJ defines regions into 0 ~ 5 risk level,
where more than 2 means frost damage
risk zone.
• N = 10 {(90.14ln(C/W) + 0.04) θ + 3.15ln(C/W) + 1.43}
• N : Number of fracture cycles
• C/W： Reciprocal of W/C ratio，
• θ ： Minimum temperature (℃)
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22. 2.5 Application of High
Durability Concrete in Korea
(국내 고내구성 콘크리트 적용 사례)
• HDC is still not so popular in Korea, but
advanced countries have been using
concept of durability design.
• But, high-strength concrete with fck > 400
MPa are used in super high rise buildings.
• But, high-strength concrete doesn’t mean
high durability concrete. It should be under
durability design as defined by AIJ.
Required
Characteristics Test Test Conditions Criteria
Neutralization
Accelerated neutralization
test
Temp. 20℃，Rel.humidity60 %,
CO2 5 % for 26 week
less than 25 mm
Drying Shrinkage Deformation Test 6 month less than 0.7 mm/mm
Bleeding Amount Bleeding Test
-
less than 0.3 cm2
/cm2
Durability index Freezing and thawing test 300 cycles less than 85%
Required Properties of High Durability Concrete, Architectural Institute
of Japan
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24. 3.6 Conclusion (맺음말)
• High Durability Concrete:
1. Compressive Strength > 600 Mpa
2. 100 years life without maintenance and 500
years with maintenance.
• Considering Factors in High Durability Design:
1. External Deterioration Factors: Carbonation,
Frost Damage, Neutralization, etc.
2. Reducing pores in concrete with admixtures like
Silica ware, blast furnace, fly ash, etc.
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25. 발표 들어주셔서
감사합니다!
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