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


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



Step 2: Clean and paint the corroded steel bars


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Step 3: Patch the hacked area


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Step 4: Paint the area


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Removal of Loose Concrete on Ceiling


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
















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We specialise in the professional repair of spalling concrete issues.
Spalling Concrete Prevention
Spalling Concrete Inspection
Perform initial inspection to assess condition of spalling concrete on ceilings and walls
Professional Rectification
Employ professional standards to spalling concrete repair method to preserve safety and structural integrity
Regular Maintenance
Perform regular maintenance of compromised concrete surfaces to prevent onset of spalling concrete issues
About Spalling Concrete
Especially in older buildings, spalling concrete is a prevalent surface maintenance issue. It is suggested that repair be done as soon as spalling concrete is observed as it can cause passerby risk.

A natural deterioration method called carbonation is mainly triggered by spalling concrete. This triggers corroding of the steel bars inserted in the ceiling slab, causing cracking and bulging of the concrete cover.

In reinforced concrete structures, spalling concrete is usually a surface maintenance issue. It does not impact the structural integrity of the construction if attended to immediately.

Spalls may appear as the rebar was exposed and humidity and water started rusting the rebar or as the concrete joints were improperly constructed. The concrete extends as the weather changes, causing it to spin, leading to further deterioration. One method that can avoid spilling of concrete is to apply a healthy water sealant to the completed surface to avoid water from entering the concrete.


Spalls can also be avoided if the concrete is carefully managed and suitable techniques are used when poured, such as providing adequate concrete cover (embedding) of the rebar and placing joints at the right locations and the right distances. Always pay special attention to the edges and corners of exposed concrete as specified by the structural engineer to ensure adequate concrete cover. The concrete mix is another important factor to consider, as the surplus water content can also lead to spalling.


Spalling Concrete Repair

Usually, spalling concrete within HDB flats will be minor with periodic maintenance and can be easily repaired. If the spalling concrete is left unattended for a long time, however, it will spread to a larger area and weaken the structure of the building.


The steps below show briefly how to repair spalling concrete. Do remove any loose spalling concrete while waiting for the repairs to avoid injury to inhabitants.

Step 1: Remove the spalled concrete

Remove the concrete from the spalled regions to expose the corroded steel bars.

Step 2: Remove rust from corroded steel bars

Scrape and clean the exposed steel bars and use a wire brush to remove any visible rust on all surfaces. Next, apply two coats of anti-rust oil all around the exposed steel bars.

Step 3: Patch the hacked region

Apply a bonding agent to the impacted surface to guarantee adequate adhesion.

Additional Tips for Repairing Spalling Concrete


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