Questions about Rebar Anomalies and Maintenance in Concrete Structures

[jikewang]

Hi all,
I'm very interested in how anomalies in embedded rebars within concrete walls are detected and assessed, and would appreciate insights from professionals in this field.
I have a few key questions:

• What are the most common rebar anomalies inside concrete walls? Is rebar corrosion the main concern?
  What detection methods are typically used, electrochemical?
  
  
• Are non-corrosion anomalies also important to monitor?
  • Can rebar fracture occur in practice (e.g., due to earthquakes or severe corrosion), and is it a real concern?
  • What about bending of rebar or spacing shifts between rebars, do small deviations impact structural safety or require attention?

Any feedback would be greatly appreciated.
Thank you!

 

[LittleWheels]

I mostly want to know how much rebar is within a RC wall and at what spacing. Ferroscan surveys or GPR are the most common methods. Detailing (lap length, multiple rebar layers) can be a issue but can more difficult to determine non-destructively.

I also want to know if corrosion is occurring in older structures but that requires a combination of techniques to get reasonable confidence regarding the results. Some combination of half-cell potentials, delamination, alkalinity and chloride content surveys makes a decent start but there are other methods that can be helpful too.

Rebar fractures can certainly occur in extreme circumstances but typically there is visual evidence of that.

There are plenty of potential concerns that apply to RC walls (and other RC structures e.g. ASR, DEF, thaumasite) but that is a whole other subject.