doi:10.3850/978-981-08-7920-4_S3-I008-cd

ABSTRACT

Results of various non-destructive tests conducted on 35-year old chemical plant exposed to corrosive chemical fumes established that distress of structure was due to chloride-induced corrosion. The influence of chloride ions on parent mortar microstructure before repair was investigated in terms of carbonation, chloride content, pH value, corrosion products and nature of distress to which structure was subjected. Depth of carbonation and presence of chloride ingression were assessed and it was confirmed that corrosion was due to chloride ingression. The plant was refurbished five years ago using M35 grade, presumably a dense and low permeable self-compacting concrete as overlay. All the exposed concrete surfaces were coated with a breathable protective material. During refurbishing, efforts were made to remove all the carbonated and chloride-induced concrete up to reinforcement level. However chlorides could still be in the parent concrete. The possibility of transportation of residual chlorides from M15 grade parent concrete to repair mortar is monitored with embedded potential and corrosion rate monitoring sensors. These sensors were embedded at strategic locations where severe corrosion andmore chloride contentwere reported before repair. The results of embedding sensors for last four years were analyzed and a perfect passive condition was found in almost all the locations.

Keywords: Chloride, Corrosion, Self-compacting concrete, Embedded sensors, Electrochemical measurements, Non destructive testing.

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