The earthquake and tsunami of 26 December 2004 caused the infrastructure in Aceh’s West Coast region to be submerged by seawater and to require the rehabilitation and reconstruction. The infrastructure that was submerged in the tsunami might experience a decrease in strength due to corrosion attack and would unexpectedly collapse if an earthquake occurs even on a small scale. This study was conducted to examine the corrosion risk level of the infrastructures in Aceh’s West Coast region, Indonesia, which submerged by the 2004 tsunami. Three locations were chosen for the study, i.e., Suak Ribee, Ujong Kalak, and Padang Seurahet. The assessments were carried out in 2014 and 2015. Three to four columns in each of the buildings were selected for the assessment. The half-cell potential technique method which refers to ASTM C876 was used to obtain and analyze the assessment data. The results of the assessment show that the electrical potentials on the surface of concrete for the buildings which submerged by the tsunami were range between -100 and -450 mV (vs. Cu/CuSO4) and categorized into low to high corrosion risk level. Meanwhile, the electrical potentials for new buildings range between (-100) and (-350) mV which indicated low to medium corrosion risk. Hence, the corrosion actively occurred in the areas having medium to high corrosion risk. Also, it was found that the corrosion risk level for the building tends to increase by increasing time. Therefore, the prevention and/or rehabilitation is necessary for stopping the corrosion, and so the premature failure of the building might be avoided.
The West Aceh region is vulnerable to catastrophic earthquakes [
To avoid the possibility of a sudden failure of the infrastructures, especially in the regions hit by the 2004 tsunami in West Aceh, corrosion assessment must be done to determine the level of corrosion risk of reinforced concrete infrastructures, and it is important to be performed periodically. Hence, this study aims to conduct an assessment in order to determine corrosion risk level of reinforced concrete buildings in West Aceh region. For this study, the half-cell potential technique is used by obtaining electrical potential on the surface of the concrete.
The half-cell potential technique is a nondestructive test widely used to monitor and determine the corrosion of reinforced concrete infrastructures [
Criteria for corrosion risk levels with referring to ASTM C876 [
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1 | > (-200) | > (-100) | > (+120) | > (-80) | Low (10% risk of corrosion) |
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2 | (-200)– (-350) | (-100)– (-250) | (+120) – (-30) | (-80) – (-230) | Intermediate corrosion risk |
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3 | < (-350) | < (-250) | < (-30) | < (-230) | High ( >90% risk of corrosion) |
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4 | < (-500) | < (-400) | < (-180) | < (-380) | Severe corrosion |
Comparison of half-cell potential technique result to the actual corrosion in the previous result [
Electrical potential measurement with half-cell potential technique.
This assessment was carried out in the region hit by the 2004 tsunami, especially West Aceh Regency. Three locations were selected in the regions, i.e., Suak Ribee (Objects I and III), Padang Seurahet (Object II), and Ujung Kalak (Object IV).
The first study was conducted in August 2014 and the second in June 2015. Two reinforced concrete buildings that submerged by the tsunami (Objects I and II) and two new buildings built after the 2004 tsunami (Objects III and IV) were selected in this study. The locations of the buildings/objects can be seen in Figure
The locations of the reinforced concrete building for the study.
(a) Rebar locator (profometer 5+) and (b) SCRIBE DHC digital half-cell meter.
Then, for every building, at least three columns were selected to be measured to their corrosion potential. On each column, the location of the reinforcement was determined with the rebar locator. Then, a grid was constructed on the surface of the column corresponding to the location of the reinforcement. The four buildings are shown in Figures
Buildings submerged by the tsunami: (a) Objects I and (b) Object II.
New buildings: (a) Objects III and (b) Object IV.
Next, the four buildings were assessed for their corrosion risk levels. Every column for buildings to be assessed was shown in Figures
Schematic sketch for (a) Object I and (b) Object II.
Schematic of column position of (a) Object III and (b) Object IV.
(a) Measurement of the location of steel reinforcement and (b) potential corrosion measurement of the column.
The potential corrosion data which were obtained on the reinforced concrete structure were mapped using the software VisIt-2.7.3. The software is an open source. It used to generate color contour represented potential values on the columns of the building.
Figure
The potential distribution on each column of Object I for 2014 and 2015.
Referring to Table
The increasing of corrosion risk level of the columns was consistent with the previous study conducting the half-cell potential mapping in Banda Aceh city, Indonesia [
The potential distribution on the column for the previous study in Banda Aceh city, Indonesia: (a) indicating an increase of corrosion risk and (b) indicating repassivation [
Another assessment result for infrastructure submerged by the 2004 tsunami was given in Figure
The potential distribution on each column of Object II for 2014 and 2015.
Using the criteria in Table
The phenomenon that the corrosion worsened by increasing time can be confirmed by looking at Figure
The visual of a column of Object II for (a) 2014 and (b) 2015.
Moreover, the potential distribution for one of the infrastructures built in the tsunami-affected area (Object III) was shown in Figure
The potential distribution on each column of Object III for 2014 and 2015.
The potential values on the columns of Object III might be categorized into low to intermediate corrosion risk level by referring to the criteria in Table
Furthermore, by conducting a visual inspection, it was found that there was a difference on the condition between the column directly facing the sea and the column facing the opposite direction of the sea as seen in Figure
The visual of a column of Object III for (a) directly facing to the sea and (b) facing to the opposite of sea.
The potential distribution for the last infrastructures was shown in Figure
The potential distribution on each column of Object IV for 2014 and 2015.
Based on the criteria in Table
By comparing the assessment results of the 2014 and 2015 data, a tendency of increasing the negativity of corrosion potential values is shown. This means that the corrosion actively occurred on the reinforcing steels. Furthermore, this shows that the new structures built in the tsunami-affected area would be susceptible to corrosion attack indicated by its intermediate corrosion risk level. These results were consistent with assessment results conducted around Banda Aceh city [
The corrosion risk assessment based on ASTM C876 has been conducted for four infrastructures in West Aceh Regency, Aceh Province, Indonesia. The results show that some parts of the structures were already at intermediate to high corrosion risk level. The structures that submerged by the 2004 tsunami show the tendency at higher risk than the structures built after the 2004 tsunami. However, these structures are also already at intermediate corrosion risk level. This indicated that the corrosion actively occurs for all infrastructures. Hence, the rehabilitation and/or protection is necessary to be carried out in order to prevent the corrosion worsening and so the premature failure might be avoided.
The data used to support the findings of this study are available from the corresponding author upon request.
The authors declare that they have no conflicts of interest.