Spalling Concrete

Spalling concrete is a common issue for older buildings. It is largely caused by carbonation, a natural deterioration process. This causes the steel bars embedded in the ceiling slab to corrode, which in turn causes the concrete cover to crack and bulge. As the owner, you are responsible for the repair of any spalling concrete in your flat.

How to prevent spalling concrete

Spalling concrete is a surface maintenance problem that occurs in reinforced concrete structures. If attended to immediately, the building’s structural integrity will not be affected.

Here’s how spalling concrete can be prevented:

Paint ceilings regularly

Paint protects your ceiling and helps to prevent carbonation. Ideally, you should paint your ceiling regularly.

Seal cracks/ holes properly

Check your ceiling regularly for any holes or cracks. These should be sealed immediately to prevent moisture and carbon dioxide from entering the concrete. Similarly, seal up any holes drilled into the ceiling that are no longer in use (e.g. holes left after a ceiling fixture is removed).

Ensure sufficient ventilation

A humid environment will speed up carbonation. To reduce the humidity in moisture-prone areas such as the kitchen, toilet, and bathroom, open the windows, vents, or doors when the areas are not in use.

Repairing spalling concrete

With regular maintenance, spalling concrete within HDB flats will usually be minor and can be easy repaired. However, if the spalling concrete is left unattended over a long period, it will spread to a bigger area and weaken the building structure.

The steps below briefly show how spalling concrete is repaired. For more details, please watch this video.

Step 1: Remove the spalled concrete

• Remove the concrete at the spalled areas to expose the corroded steel bars

Step 2: Clean and paint the corroded steel bars

• Scrape and clean the exposed steel bars and use a wire brush to remove any rust
• Apply 2 coats of anti-rust paint to the steel bars

Step 3: Patch the hacked area

• Apply a bonding agent to the affected surface to ensure proper adhesion
• Patch the hacked area using polymer modified cement mortar

Step 4: Paint the area

• Paint over the patched area to match the rest of your ceiling

Removal of Loose Concrete on Ceiling

While waiting for the repairs, do remove any loose spalling concrete to prevent injury to your family members.

STEP 1 :

• You should wear a pair of protective gloves, and prepare a hammer and chisel to remove the loose concrete
• You can replace the chisel with a long flat point screw driver

STEP 2 :

• Cover the floor and protect the surroundings with thick cardboard
• Secure the ladder and climb up to remove the loosen concrete.
• Hold the affected portion of concrete and bring it down carefully

STEP 3 :

• Collect the concrete debris and dispose it safely at the bin centre

Repair Contractors

You can engage any of the following contractors to repair spalling concrete in your flat.

1) Our list only serves as a guide and is not meant to be exhaustive or an endorsement of the contractor’s performance.

2) You might want to also consult sources such as the Yellow Pages (Commercial/ Industrial Guide) before engaging a contractor.

3) You may contact the contractor during working days, Monday to Friday from 9:00am to 5:00pm.

4) If you would like to engage any of the above contractors, you will have to negotiate the price and extent of work with the contractors on a private basis.

5) You need to ensure that the contractors you engage exercise due care and diligence while carrying out the necessary repair work.