[HOME RENOVATION DIY] HOW TO REPAIR SPALLED CONCRETE? CAUSES AND REPAIR TEACHING

Maintenance & Repair

Published on: January 11th, 2021
5 minutes read

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How to repair spalled concrete? How much does the repair cost? Is there any repair material? Recently, many of my friends told me that they experienced the spalled concrete at home which worried the elderly very much. Actually, it is not difficult to fix the problem by ourselves at all. You just need to clean the debris, steel bars and cover up with cement.

The ultimate guide to repair spalled concrete

Cause:

Due to moisture or water seepage problems, the steel bars in the concrete are oxidized and rusted, which expands and explodes the stone walls.

Solutions:

Fix the water seepage problem first.
Fix the rusty steel bars.
Clean up the debris.
Mix cement, sand, water and cement bonding agent and fill the area where the concrete peels.

The cause of concrete spalling: Exposed rusty steel bar

Most of the reasons for concrete spalling in the ceiling are water vapor or water seepage. The steel bars in the concrete are oxidized and rusted. They expand and explode the stone wall, causing the concrete to peel and the steel bars to be exposed. Therefore, the first step to solve the problem is to check whether there is water leakage at home.

If the rise in water vapor causes the steel bars to expand and the stone wall to peel off, you need to use aluminium or gypsum board ceiling to block the effect of moisture on the steel bars.

How to repair spalled concrete by yourselves

Step 1: Clean the rusty steel bars

After fixing the rusty steel bars, you need to clean the clean and remove the falling concrete debris. The steps are as follows:

Clean up the concrete debris.
Grind and clean the rusted steel bars with a wire brush.
Apply anti-rust oil to the steel bars.
Then carry out the concrete repair work.

Step 2: Organize the repair materials

After cleaning the concrete debris, you need to cover up the peeled areas with cement. The steps are as follows:

Prepare cement, sand, water, and cement bonding agent (facilitate cement to be stronger and waterproof).
Mix sand with cement. Add sand first, then cement. The ratio is 4 parts of sand + 1 part of cement. Then mix it to light grey.
Add water and cement bonding agent.
Mix the above four together to become a composite mortar.

When the composite mortar dries, the originally filled area will sag, so a second coat is required. Therefore, when you apply the first layer of composite mortar, you don’t need to smoothen the surface but to make it as rough as shown in the above image to facilitate the laying of a new layer of composite mortar.

Step 3: Repair the concrete wall

You can apply the composite mortar on the wall where the concrete falls. When the composite mortar dries, the originally filled area will sag, so a second coat is required. Therefore, when you apply the first layer of composite mortar, you don’t need to smoothen the surface but to make it as rough as shown in the above image to facilitate the laying of a new layer of composite mortar.

In summary, in order to repair spalled concrete, you have to deal with the rusty steel bars first. Then clean up the falling concrete debris, and then cover with composite mortar.

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This article was originally published on HKDecoman.

HKDecoman, now going global as Deco-Man, is a Hong Kong-based renovation platform which provides professional consultancy services and pioneers in the development of A.I. homeowner-engineer matching. We aim at educating the public about the art of home renovation, and have our eyes on transforming the traditional renovation industry, bringing standardisation, transparency, convenience and automation to the business.