The "Weak Column" Test: 5 Warning Signs

Before you panic, look closely at the column and check for these specific symptoms.

1. Vertical Cracks (The Corrosion Sign)

What it looks like: A straight crack running up and down the length of the column.

• The Cause: This usually means the steel inside is rusting (corroding). When steel rusts, it expands and pushes the concrete cover outward, splitting it vertically.
• Is it Weak? It means the durability is compromised. If left untreated, the steel will lose its strength.

2. Horizontal Cracks (The Danger Sign)

What it looks like: A crack running sideways (left to right) across the column face.

• The Cause: DANGER. This is often a sign of "Tensile Failure" or buckling. It means the column is bending under a heavy load or a lateral force (like wind or earthquake) that it cannot handle.
• Is it Weak? Yes. A truly weak column cracks horizontally. This requires immediate attention.

3. Diagonal Cracks (The Shear Failure)

What it looks like: A crack running at a 45-degree angle, often near the top or bottom of the column.

• The Cause: This is called Shear Failure. It happens when the load is too heavy for the column's cross-section to bear, causing it to slide or snap diagonally.
• Is it Weak? Critical. Shear failure is "brittle," meaning it can happen suddenly without warning.

4. Visible Reinforcement Bars (Spalling)

What it looks like: Chunks of concrete have fallen off, exposing the rusted steel bars inside.

• The Cause: Advanced corrosion. The rust pressure has become so great that it has burst the concrete cover.
• Is it Weak? Yes. The "skin" of the column is gone, and the steel bars are now being eaten away by the air. The column's diameter is effectively reduced.

5. Crushing at the Ends

What it looks like: Small pieces of concrete are crumbling or spalling off at the very top (near the beam) or very bottom (near the floor).

• The Cause: Overloading. The column is being crushed by the weight of the floors above.

How to Be 100% Sure: Ask for Professional Help

You cannot judge concrete strength just by looking at it. To be certain, you need to ask for help from a Professional Structural Damage Inspection service.

Why hire a professional?

1. Identification: They know exactly which column is damaged and which is safe.
2. Investigation: They use scientific tools (like Rebound Hammer and UPV tests) to investigate why it failed.
3. Solution: Most importantly, they will give you the correct, engineered solution—whether it needs simple plastering, retrofitting, or strengthening.

Conclusion: Safety First

A crack in a column is your building trying to talk to you.

• Vertical hairline cracks = Maintenance Issue (Fix it soon).
• Diagonal or Horizontal cracks = Weak Column (Call an Engineer NOW).

Don't guess with your safety. If you see visible steel or deep cracks, ask a professional to investigate and provide the right solution.