Condition Assessment of Concrete Pier Shaft Segment from Bridge in Central Canada

A pier shaft segment from a semi-submerged section of a highway bridge after approximately 60 years in service was investigated using visual, non-destructive, and microscopic analysis. The bridge was exposed to hot, humid summer weather and freezing winters including ice buildup on the waterway. Deterioration mechanisms which might be occurring include delayed ettringite formation, freeze–thaw damage, and alkali-silica reaction. Reinforcement corrosion is also possible; however, it is unclear whether this section of the bridge had high exposure to chlorides. The visual analysis consisted of qualitative observations, supplemented by semi-quantitative (crack measurements) and quantitative (using the cracking index) assessment. Surface condition was poor including surface discoloration and a pockmarked appearance due to deteriorated aggregate. Cracking index values ranging from 0.4 to 7.7 mm/m were recorded due to the large width of some surface cracks. Non-destructive tests conducted included ultrasonic pulse velocity, Schmidt hammer, and surface resistivity. Cores were subsequently extracted from the pier shaft segment, some of which were selected for investigation using the damage rating index microscopy technique. Future work includes mechanical testing of extracted cores including compressive strength tests and the stiffness damage test.