Corrosion Risk of Patch Repaired Reinforced Concrete Elements Under Influence of Internal Chloride Ions

The durability of reinforced concrete structures is always distracted by the penetration of harmful ions such as chloride that leads to spalling, cracking and delaminating of concrete structures. To rehabilitate the deteriorated concrete structures, patching method with polymer modifier mortar (PMM) was investigated to analyze their performance under the influence of chloride ions and to predict their corrosion risk tendency. The effectiveness of patching method was assessed and compared using different repair materials, namely, OPC with W/C of 40% and PMM that were cast in prism shape specimens containing free chloride ions respectively. The substrate concrete containing 9 kg/m3 chloride ions is indicated as the reference specimen. The corrosion activities have been analyzed using visual inspection and microstructural analysis, concrete resistivity, chloride content and half-cell potential. The measurements revealed that all test specimens show initiation of corrosion attacks with the reference specimen found to have greater result as it contains chloride ions for the whole specimen. Meanwhile, repaired specimens that have partially contained chloride ions also show the corrosion attack but has less than the reference specimen. The correlation between Ca/Si ratio and free and total chloride content can explain the chloride binding in the test specimens. Moreover, the result obtained from concrete resistivity has a significant correlation between Ca/Si ratio and chloride content in the test specimens. To summarize, R-PMM specimen is revealed to be good in chloride resistance but since it shows contradiction in the corrosion risk, this phenomenon is somehow associated to the diffusivity and permeability coefficients.