Proceedings of the International rilem conference Materials, Systems and Structures in Civil Engineering 2016

35

International RILEM Conference on Materials, Systems and Structures in Civil Engineering 

Conference segment on Service Life of Cement-Based Materials and Structures

 

 

22-24 August 2016, Technical University of Denmark, Lyngby, Denmark 

 

cover thickness, which indicates that corrosion has not initiated yet, despite the building being 

53 years of age. 

 

 

HCP> 200mV

HCP< 300mV

200mV HCP 300mV

(cm)

(cm)

 

Figure 4: HCP measurement over Console 2 

 

Figure 5: Carbonation depth versus time

 

---

36

International RILEM Conference on Materials, Systems and Structures in Civil Engineering 

Conference segment on Service Life of Cement-Based Materials and Structures

 

 

22-24 August 2016, Technical University of Denmark, Lyngby, Denmark 

 

5.2 Comparison of estimated probability of corrosion initiation with field investigations 

Considering Tab. 3, the overall weighted probability of corrosion initiation for each console is 

estimated, and the results are given in Tab. 4. According to Tab. 4, it can be seen that the steel 

reinforcements in each console have overall less chance (about 10% - 19%) of corrosion 

initiation. In addition, it can be seen that the area which is considered as partially exposed to 

rain has 10% to 19% chance of corrosion initiation. However the area which is considered to 

be sheltered from rain has10%  chance of corrosion initiation. In this case, HCP mapping 

gives unrealistic results. In addition, the estimated probability of corrosion initiation at the age 

of  53 years, given in Figure 2, is 22.5% for the area sheltered from rain and 4% for the area 

exposed to rain. The field investigated corrosion initiation probabilities are lower than those 

for the area sheltered from rain and higher than those of the area with partial exposure to rain. 

 

Table 4: Summary of HCP measurement over consoles 

(Note: (a) area sheltered from rain and (b) area partially exposed to rain) 

 

6. Discussion and conclusion 

Carbonation can be considered as the dominant mechanism for the corrosion of reinforcement 

in residential buildings. Hence, the carbonation depths were measured in three consoles of no 

visible corrosion in a 53-year-old residential building, considering exposure to rain and 

shelter from rain. It could be seen that the measured average carbonation depth at the side 

sheltered from rain was 7 mm (X1) and that of the side partially exposed to rain was 4.5 mm 

(X2). Considering the mean values of random variables, the calculated mean carbonation 

depth is 18 mm for the side sheltered from the rain and 8.7 mm for the side partially exposed 

to rain. It could be seen that the calculated mean carbonation depths are higher than the 

measured carbonation depths. Moreover, painting of the surface may hinder the carbonation 

process, resulting in lower measured carbonation depths than expected.

 

Furthermore, the 

probability of corrosion initiation was estimated using Monte Carlo simulation; results were 

22.5% at 53 years for the area sheltered from rain. The HCP measurement at 53 years shows 

that the percentage chance of corrosion initiation for the same area is 10-19%, which is lower 

than the estimated probability of corrosion initiation. This implies that the estimated 

probability of corrosion initiation provides a good safety margin in designing the concrete 

cover.  

 

 

Half-cell potential 

(mV) (Re. Cu/CuSO4 

reference electrode) 

 

Percentage 

chance of 

corrosion 

initiation 

Frequency of occurrence of HCP value 

Console 1 

Console 2 

Console 3 

(a) (b) (a) (b) (a) (b) 

<-300 

90%  0 0 0  0  0  0 

-200 

to 

-300 

50%  0 0 0  4  0  2 

>-200 

10%  18 18 18  14  18  16 

Overall weighted probability of 

corrosion initiation 

10% 10% 10%  19%  10% 14 

% 

---

37

International RILEM Conference on Materials, Systems and Structures in Civil Engineering 

Conference segment on Service Life of Cement-Based Materials and Structures

 

 

22-24 August 2016, Technical University of Denmark, Lyngby, Denmark 

 

References 

[1]

 

Fib_bulletin_34, Model code for service life design, ISBN 978-2-88394-074-1 (2006) 

[2]

 

DuraCrete, Modeling of degradation, BRITE–EURAM-Project BE95-1347/R4-5 (1998) 

[3]

 

DuraCrete, Statistical quantification of the variables in the limit state functions, BRITE–

EURAM-Project BE95-1347/R9 (2000) 

[4]

 

Tuutti, K., Corrosion of steel in concrete. Stockholm, Sweden: Swedish Cement and 

Concrete Research Institute (1982) 

[5]

 

Fib_bulletin_59, Condition control and assessment of reinforced concrete structures 

exposed to corrosive environments (carbonation/chlorides): State of the art, ISBN 978-2-

88394-099-4 (2011) 

[6]

 

Samarakoon, S. M. S. M. K. and Sælensminde, J., Condition assessment of reinforced 

concrete structures subject to chloride ingress: A case study of updating the model 

prediction considering inspection data, Cement Concr Compos 60 (2015), 92–98 

[7]

 

Malioka, V., Condition indicators for the assessment of local and spatial deterioration of 

concrete structures, PhD thesis, Swiss Federal Institute of Technology, Zurich, (2009) 

[8]

 

ASTM C876, Standard test method for half-cell potentials of uncoated reinforcing steel in 

concrete, 03(02) (1991), 434-9 

 

 

---