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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