UK-China Science BridgeRemote Monitoring of Corrosion Activity Remote Monitoring of Corrosion Activity

of Concrete at Hangzhou Bay Bridgeof Concrete at Hangzhou Bay Bridge

Introduction Exposure SiteIntroduction Exposure Site

Concrete structures in marine environments experience deteriorationcaused by reinforcement corrosion due to external salts, freeze-thaw,

Hangzhou Bay Bridge is one of the longest trans-oceanic bridge in the world; Length 35.6 kmcaused by reinforcement corrosion due to external salts, freeze-thaw,

repeated wetting and drying cycles, abrasion due to wave impacts andbiological attack. In general, corrosion of reinforcement caused due to carbonation,

oceanic bridge in the world; Length 35.6 km Aggressive environment with tidal variations up to

9m height and waves travel at 30 kmph The exposure site located underneath the service In general, corrosion of reinforcement caused due to carbonation,

chloride ingress and leaching account for more than 50% of thereported cases in concrete structures. The environmental factors that influence the deterioration mechanisms

The exposure site located underneath the servicecentre and hotel built at the mid-length of thebridge Three different types of concrete C30, C40 and The environmental factors that influence the deterioration mechanisms

are moisture, temperature, wind, carbon dioxide and salts from the seawater. FINAL STAGE

It is essential to

Three different types of concrete C30, C40 andHPC exposed at four different levels viz.,Atmosphere zone, Splash zone, Tidal zone andSubmerged zone

Deg

ree

of D

eter

iora

tion

Initiation period Active period

Initiation of

It is essential tocontinuously monitor theperformance of concretestructures right from the

Submerged zone

Deg

ree

of D

eter

iora

tion

Time Service life

Initiation ofdeterioration

Propagationof deterioration

Changes ofmaterial properties

structures right from theconstruction phase tothe end of service life ofthe structure

Results and ConclusionsSensor Technique and Monitoring System

Time Service life

Monitor and Test

Results and ConclusionsSensor Technique and Monitoring SystemEarly age concrete

4

5

80mm50mm30mm10mmty

(k

ΩΩ ΩΩ-c

m)

C30

4

5

80mm50mm30mm10mmty

(k

ΩΩ ΩΩ-c

m)

C40

4

5

80mm50mm30mm10mmty

(k

ΩΩ ΩΩ-c

m)

HPC

Early age concrete

The integrated sensor probe consists of threedifferent sensors viz. 2-pin electrical resistancesensor array, temperature sensor and corrosion

0

1

2

310mm

ectr

ical

Res

istiv

it

0

1

2

310mm

ectr

ical

Res

istiv

it

1

2

310mm

ectr

ical

Res

istiv

it

sensor array, temperature sensor and corrosionsensor. The electrical resistivity or conductivity measured at

different depths in the cover zone of concrete can 00 20 40 60 80 100

Time (hrs)

Ele 0

0 20 40 60 80 100

Time (hrs)

Ele 0

0 20 40 60 80 100

Time (hrs)

Ele

The electrical resistivity changes monitored for C30, C40 and HPC concrete shows three different phases associated to the setting characteristics of concrete

different depths in the cover zone of concrete canbe related to early age properties of concrete suchas rate of hydration, setting characteristics, micro-structure formation and long-term changes in shows three different phases associated to the setting characteristics of concrete

and pore structure formation in the concrete The prolonged increase in electrical resistivity observed for HPC concrete clearly

shows the influence of slow pozzolanic reaction by the mineral admixtures viz.

structure formation and long-term changes intransport properties of concrete in the cover zone

The temperature sensors placed in fourdifferent depths helps in monitoring the shows the influence of slow pozzolanic reaction by the mineral admixtures viz.

Flyash and GGBS in the concrete mix The spatial distribution of electrical resistivity was able to monitor the influence of

curing, which resulted in lower resistivity values at the 10 mm depth in comparison to resistivity at 80 mm depth

different depths helps in monitoring thethermal gradients in concrete The surrounding environmental data

monitored using weather station in

8 )) ))

C40 - Level4

8 )) ))

C30 - Level4

8 )) ))

HPC - Level4

Concrete exposed to marine environment (atmosphere zone)comparison to resistivity at 80 mm depth

monitored using weather station incombination with the electrical resistivity,temperature and corrosionmeasurements help in predicting the

2

3

480 mm50 mm30 mm10 mm

tivity

Rat

io (

ρρ ρρt/ ρρ ρρ

28

2

3

480 mm50 mm30 mm10 mm

tivity

Rat

io (

ρρ ρρ t/ ρρ ρρ

28

2

3

480 mm50 mm30 mm10 mm

tivity

Rat

io (

ρρ ρρt/ ρρ ρρ

28

measurements help in predicting theremaining service life of the concretestructure The monitoring control system installed at Hangzhou bay bridge can be

remotely operated from QUB, Belfast

0

1

0 20 40 60 80

Time (Days)

Ele

ctric

al R

esis

t

0

1

0 20 40 60 80

Time (Days)

Ele

ctric

al R

esis

t

0

1

0 20 40 60 80

Time (Days)

Ele

ctric

al R

esis

t

remotely operated from QUB, Belfast The corrosion activity data and weather conditions at the bridge are

automatically transmitted to a central PC at QUB through cloud computing.Time (Days)Time (Days) Time (Days)

The electrical resistivity changes at 10mm depth from the surface for C30, C40 and HPC concrete increases with time and fluctuates in response to the diurnal variations in external temperature and moisture conditions.

Weather

Station

variations in external temperature and moisture conditions.

AcknowledgementsElectrical resistivity

Temperature sensors Monitoring

Station

Remote

PCCloud

computing AcknowledgementsThe authors would like to acknowledge the financial support from Engineering and Physical Sciences Research Council of UK through project grant EP/G042594/1and EP/G02152X/1. The support provided by bridge authority at Hangzhou Bay Corrosion

Electrical resistivity

sensors

computing

Srinivasan S, Basheer PAM, Mao J, Jin W -L, McCarter W.J,

and EP/G02152X/1. The support provided by bridge authority at Hangzhou Bay Bridge is greatly acknowledged..

Corrosion

Sensors

Srinivasan S, Basheer PAM,Queen’s University Belfast, UK

Mao J, Jin W -L,Zhejiang University, China

McCarter W.J,Herriot-Watt University, UK