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TRANSCRIPT
Maria Cruz Alonso
MISURARE E «MONITORARE» LA DURABILITA:
Predictive monitoring systems for rebar corrosion
assesment in aggressive environments
DURABILITY IN THE SERVICE LIFE OF THE STRUCTURES
• What are the aims for the service life of a structure? Identification of the exposure site aggressiveness (Std. classification) Recommendations from codes & standard for durability designIdentification of damage expectances Service life estimation length at project design
• When a structure should be monitored?Who takes the decisionAdditional monitoring measures during the service life
• How to select the most suitable monitoring system? Location of the structure and structure typologyMonitoring length and time scale Durability of structure vs. durability of the monitoring system
• What expectances of the owner from monitoring system?
Why rebar corrosion is a risk in service life of structures?
Alkaline Cover
Passive layer
En
vir
on
me
nt
CO2
Clˉ
En
vir
on
me
nt
CO2
Clˉ
Clˉ Clˉ
Pas
sive
laye
ral
tera
rio
Passive layer
Bro
ken
pas
sivi
typ
itti
ng
En
vir
on
me
nt
CO2
Clˉ
Dap
En
vir
on
me
nt
CO2
Clˉ
Dap Cl crit
Parameters to monitor service life of concrete structures
REBAR MONITORING
•Corrosion potential• Corrosion rate
CONCRETE MONITORING
• Electrical resistivity• pH changes• Cl content
CHANGES IN CONCRETE AND REBAR OCCUR DUE TO AGGRESSIVES ENTRANCE
Density Plot (Normal (Gauss))-Cl-
0.21 0.30 0.40 0.49 0.58 0.68 0.77 0.87 0.960.00
0.28
0.55
0.83
1.11
1.38
1.66
1.94
2.21
2.49
2.77Relative Frequency
Import Data ( Cl Total)
Density Plot (Normal (Gauss))-Cl-
0.21 0.30 0.40 0.49 0.58 0.68 0.77 0.87 0.960.00
0.28
0.55
0.83
1.11
1.38
1.66
1.94
2.21
2.49
2.77Relative Frequency
Import Data ( Cl Total)
Density Plot (Normal (Gauss))-Cl-
0.21 0.30 0.40 0.49 0.58 0.68 0.77 0.87 0.960.00
0.28
0.55
0.83
1.11
1.38
1.66
1.94
2.21
2.49
2.77Relative Frequency
Import Data ( Cl Total)
Density Plot (Normal (Gauss))-Cl-
0.21 0.30 0.40 0.49 0.58 0.68 0.77 0.87 0.960.00
0.28
0.55
0.83
1.11
1.38
1.66
1.94
2.21
2.49
2.77Relative Frequency
Import Data ( Cl Total)
Density Plot (Normal (Gauss))-Cl-
0.21 0.30 0.40 0.49 0.58 0.68 0.77 0.87 0.960.00
0.28
0.55
0.83
1.11
1.38
1.66
1.94
2.21
2.49
2.77Relative Frequency
Import Data ( Cl Total)
Density Plot (Normal (Gauss))-Cl-
0.21 0.30 0.40 0.49 0.58 0.68 0.77 0.87 0.960.00
0.28
0.55
0.83
1.11
1.38
1.66
1.94
2.21
2.49
2.77Relative Frequency
Import Data ( Cl Total)
Density Plot (Normal (Gauss))-Cl-
0.21 0.30 0.40 0.49 0.58 0.68 0.77 0.87 0.960.00
0.28
0.55
0.83
1.11
1.38
1.66
1.94
2.21
2.49
2.77Relative Frequency
Import Data ( Cl Total)
Density Plot (Normal (Gauss))-Cl-
0.21 0.30 0.40 0.49 0.58 0.68 0.77 0.87 0.960.00
0.28
0.55
0.83
1.11
1.38
1.66
1.94
2.21
2.49
2.77Relative Frequency
Import Data ( Cl Total)
• Monitoring with surface electrodes Periodic measurements• Monitoring with embedded electrodes Periodic vs. continuous (remote)
Sensor durability
stablecorrosiononset
Initiation period ends with
corrosion onset: ti = ttransp + tdep
Concrete monitoring of durability through embedded sensors
pH change
Electrical resistivity Segui Y. et al, mat &
struct (2017)
IETcc-CSIC
Blumentritt, 2008
Fiber optic
SMARTBOX(Giatec)
Segui Y. et al, mat & struct (2016)
Ag/ClAg
UPV
• Advantages : Possibility of periodic or continuous monitoring.
• Limitations: Need to know the life expectances of the sensor respect the
service life of the structure, pH and Cl sensors lack of market availability
Cl content
Active corr. Passive corr.
Wet sponje
voltmeter
Concrete cover
Referenceelectrode
-400 mV -200mV
On-site Ecorr
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
S1
S2
S3
S4
S5
S6
S7
S8
>-260<-250 >-400 <-400
Concrete monitoring from surface sensors / Periodic
On-site-
Rebar corrosion assessment with surface sensors/ Periodic
Direct connection of the rebar
- mapping
Ecorr- mapping
A
V
Re
= 2a Re
Electrodes
Concrete
Commercial equipment available
Rebar corrosion assessment from surface sensors / Periodic
Direct connection of the rebarEcorr/icor/
GCOR-8 (Geocisa) GALVAPULSE (German instruments)
x1/t1 =v1
Cross section or radio loss (PX = attack penetration) per unit of time (t) & unit of
total Surface (2rL)
Px = 0.0116 Icorr . t
Commercial equipment available
Icorr on embedded probes
Ecorr
Duffó et al.
Galvanic sensorINESSCOM (UPV)
INESSCOM (UPV)
ElectronicTongue
Multisensors
Remote data collection
CORROSOMETER 650c(Cosasco systems)
CONCRETE MULTI-DEPTH (Cosasco systems)
Rebar corrosion assessment from embedded sensors /Continuous
Commercial equipment availability
No market availability
Direct on the rebar
• What expectances of the owner from monitoring? Reassesment of service life prediction respect to design Identification of damage, location severityIdentification of optimal time for maintenance measures Take corrective measures in structure and in monitoringsystem
Need of multidisciplinary analyses of performance:• Rebar corrosion especialisation• Structural background performance• Electronic and data base management
DURABILITY IN THE SERVICE LIFE OF THE STRUCTURES