durability design of concrete structures enhanced by … · · 2015-05-201 annual concrete...

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Annual Concrete Seminar 2015, 29 April 2015

Durability Design of Concrete Structures Enhanced by Protective Coating in Marine Environments

Jian-Guo DAI (Dr) Associate Professor Department of Civil and Environment Engineering The Hong Kong Polytechnic University

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Outline of this presentation

1. Background 2. Importance of Protective Coating 3. Service Life Design of Marine Concrete

Structures with Protective Coating 3.1 Probabilistic theoretical model 3.2 Laboratory tests 3.3 Field tests

4. Conclusions

3 Deterioration of beams

Deterioration of slab Corrosion-induced crack

A durability failure is more often seen than a structural failure.

(Courtesy of Dr E. Kato)

Background: Steel corrosion in marine concrete structures

4 A complete loss of concrete cover.


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(Courtesy of Stephen Leung, Arap )

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Ironstone

steel cement

concrete

［high potential ］

［low potential］

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Anode Cathode Cathode Cathode Cathode

Moist concrete as an electrolyte

If anode and cathode are separated in an infinitesimal distance, then the cell is called micro-cell. If anode and cathode are separated distinctly from each other, then the cell is called macro-cell.

Background: Macro-cell and micro-cell corrosion

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Background: volumetric expansion due to oxidation o

Fe

Fe 2 O 3

FeO Fe 3 O 4

Fe(OH) 2

Fe(OH) 3

Fe(OH) 3 .3H 2 O

Volume (cm Volume (cm 3 3 ) ) 1 0 2 3 4 5 6 7

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Propagation stage

Acceleration stage

Appe

aran

ce o

f det

erio

ratio

n

Service period

Stru

ctur

al p

erfo

rman

ce Corrosion initiation

Initiation of corrosion crack

Aesthetics problem; Interfering of the third part

Increasing loss of serviceability and safety

D C A B

C

Evolution of steel corrosion in marine concrete structures

Pay here? Pay here?

Deterioration stage

Initiation stage

Source: 港湾の施設の維

持管理技術マニュアル

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Importance of protective coating

青岛胶州湾大桥: 100 years http://news.163.com/11/0701/04/77RO0CH00001124J.html

杭州湾大桥: 100 years http://www.lyzn.com/Zhejiang/Class100/20143.html

港珠澳大桥：１２０ years http://finance.people.com.cn/n/2013/1202/c1004-23718232.html

Service life extension purpose

11 Difficulty in maintenance


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Re-deterioration after repair

Patching area


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Initiation

Propagation

Acceleration

Deterioration

H2o

Preventive maintenance is very important!

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MLWL

MHWL

MLWL-1m

Marine atmosphere Splash zone

Tidal zone

Submerged zone

Below the sea bottom

Protective coating method

Cathodic protection


Example: durability design concept in case of steel piles.

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Typical protective coating

1. Topical sealer

2. Penetrating sealer

1.1 Continuous film: e.g. epoxy

1.2 Thick coating: e.g. shotcrete

2.1 Pore-blocking treatment: e.g. sodium sil

2.2 Pore-lining treatment: e.g. silane

Bertolini et al. (2004)

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Durability design of surface protected concrete structures: Theoretical modeling

Code of Practice for Structural Use of Concrete 2013: Prescriptive design approach

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Durability design of surface protected concrete structures: Theoretical modeling ( ) ( )0,

21, 0 xC

tDxerfCtxC +

⋅

−=

( ) ( )[ ] ( )72 1015.3log47.814.05.4log ×+−+= CWCWD

( ) ( )[ ] ( )72 1015.3log74.58.135.19log ×+−−= CWCWD

where C(x, t) = chloride ion content at the depth of x (cm) and at time t (years) (kg/m3) C0 = chloride ion content on the concrete surface (kg/m3) D = apparent diffusion coefficient of chloride ions (cm2/year) erf = error function C(x,0) = content of initially included chloride ions (kg/m3)

2

2 ),(),(x

txCDt

txCap ∂∂

=∂

∂

Performance-based approach: e.g. JSCE2012

Splash zone Distance from the coast (km) Near the coastline 0.1 0.25 0.5 1.0

13.0 9.0 4.5 3.0 2.0 1.5

for ordinary Portland cement

for blast-furnace slag cement

C0

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Threshold concentration

Steel reinforcement

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表面处

理层

2

2

1 xCD

tC

∂∂

=∂∂

10 hx <<

2

2

2 xCD

tC

∂∂

=∂∂

21 hxh <<

∑∞

=

−+=1

20 )exp()(

nnnn txfACC λ

+<<−−

<<=

21122122

11

11

},/)(cos[)/cos()/sin(0 ),/sin(

)(hhxhDhhx

DhDh

hxDxxf

nn

n

n

n λλ

λλ

0 10 20 30 40 500

1

2

3

氯离子浓度

(混凝土质量百分比) %

氯离子扩散深度（m m ）

有限元式（

Chl

orid

e co

ncen

trat

ion

Depth (mm)

FEM Equation

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( ) ( )Pr ,f tP t C x c t C= = ≥


Probabilistic approach

e.g., Duan et al. (2005) Duan, A., Dai, J.G. and Jin, W.L. (2015), Probabilistic Approach for Durability Design of Concrete Structures in Marine Environment, ASCE, Journal of Materials in Civil Engineering, 27, Special Issue on Sustainable Materials and Structures, A4014007.

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Durability design of surface protected concrete structures Theoretical model Variable Mean COV Distribution

D2 6×10-6

mm2/s 0.20 Log-normal

C0 2.0% 0.30 Log-normal h1 7.72mm 0.21 Log-normal h2 61.49mm 0.16 Normal n 0.25 0.20 Normal

Ct 0.5% —— Constant

0 20 40 60 80 1000

20

40

60

80

100

腐蚀概率（

%）

时间（年）

Dc

Dc/2 Dc/5 Dc/10 Dc/15 Dc/20

腐蚀概率：90%

Time (year)

Pf=

Freq

uenc

y

Concrete cover thickness

Cor

rosi

on

prob

abili

ty(%

)

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Durability design of surface protected concrete structures: Laboratory tests

Surface impregnation

Dai, J.G., Akira, Y., Wittmann, F. H. , Yokota, H. and Zhang, P. (2010), Water Repellent Surface Impregnation for Extending the Service Life of RC Structures in Marine Environment: the role of cracks, Cement and Concrete Composites, 32(2): 101-109.

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Durability design of surface protected concrete structure: Laboratory tests

ASTM C1585-04 Standard Test Method for Measurement of Rate of Absorption of Water by Hydraulic Cement Concretes

0 200 400 600 8000

3

6

9

12

15

18

21

毛细吸水量

（g）

时间（s0.5）

65-8-0 65-8-1 65-8-2

Wat

er a

bsor

ptio

n (g

)

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Charge passed (c) >4000 2000～

4000 1000～2000 100～1000 <100

Chloride ion penetrability High Moderate Low Very low Negilible

0 60 120 180 240 300 360

4

5

6

7

电流

（mA）

时间（分）

B7 B8 B19

ASTM C1202-12 Standard test method for electrical indication of concrete’s ability to resist chloride ion penetration

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Seawater Immersion Tests (e.g. NT BUILD 43: Accelerated Chloride Penetration)

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0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.00.0

0.3

0.6

0.9

1.2

1.5

氯离

子浓

度

(混凝

土质

量百

分比

）%

氯离子扩散深度（m m ）

B26-2

0 5 10 150.0

0.1

0.2

0.3

0.4

氯离

子浓

度

(混

凝土

质量

百分

比) %

氯离子扩散深度 (m m )

试验值回归值

45-1-2

Scanning electron microscope (SEM) analysis

Potentiometric titration method

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Sea water

Evaluation of surface protected cracked concrete

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Non-treated concrete (with cracks) （by means of neutron

radiography）

Contact time with water: 0 min 1 min 30 min

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Contact time with water: 0 h 2 h 48 h

Surface protected concrete (with cracks) （by means of neutron

radiography）

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0.1mm

0.2mm

0.4mm

Non-treated concrete (with cracks)

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0.1mm

0.2mm

0.4mm Surface protected concrete (with

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Durability design of surface protected concrete structure: Field tests Long-term

exposure Accelerated

test

Field exposure site in Port and Airport Research

Institute, Japan

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Durability design of surface protected concrete structure: Field tests

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Surface protected

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Shenzhen West Governmental Port (深圳西部政府码头)

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Durability of marine concrete structures is a very important issue. For a 120-year service life design, supplementary protective measures for concrete is deemed necessary based on a preventive maintenance strategy.

Conclusions

Probabilistic performance-based approach is needed for use to predict the service life of surface protected marine concrete structures.

Appropriate methods are needed for deployment to evaluate both laboratory and field performance of surface protected concrete to obtain reliable input parameters for durability design.

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Thank you for you attention.

Jian-Guo Dai at [email protected] Associate Professor Department of Civil and Environmental Engineering The Hong Kong Polytechnic University

durability design of concrete structures enhanced by … · · 2015-05-201 annual concrete...

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