Why repair concrete spalling?

Concrete spalling affects a wide variety of structures such as frame buildings, multi-storey car parks, bridges, jetties, tanks and dams. As soon as spalling is detected, it must be properly repaired, otherwise the integrity of the concrete surface is compromised and the ultimate capacity of the element is jeopardised.

Why repair concrete spalling?

Concrete spalling affects a wide variety of structures such as frame buildings, multi-storey car parks, bridges, jetties, tanks and dams. As soon as spalling is detected, it must be properly repaired, otherwise the integrity of the concrete surface is compromised and the ultimate capacity of the element is jeopardised. Spalling can occur because reinforcing bars have been exposed and moisture and water have started to rust them or because concrete joints have been constructed incorrectly. As the weather changes, the concrete expands, causing it to spall, leading to further deterioration.

One technique that can prevent concrete spalling is to apply a good water sealant to the finished surface to prevent water from entering the concrete. Concrete spalling on a horizontal surface such as a driveway or pavement is not only an aesthetic problem, but also a safety hazard. Spalling on a concrete driveway or pavement may require a more comprehensive solution to ensure that it does not reoccur. The most common method of repairing spalling on horizontal surfaces is to resurface and seal the surface with a coating solution.

The advantage of using this method is that it not only repairs the spalled concrete, but also prevents spalling problems from recurring. Concrete spalling is a fairly common problem in concrete repairs. Poor concrete installation, corrosion of rebar, freeze-thaw weathering, thawing, temperature fluctuations - all of these factors can cause concrete spalling. If left unattended, damaged concrete can compromise the integrity of the entire concrete structure.

It can lead to increased water ingress, deeper spalling, concrete crumbling, exposure of reinforcing bars and structural disintegration. In addition, concrete spalling can pose a serious safety hazard to the general public and physical property. Especially if the detached parts are located overhead, e.g. the edges of balconies, parapets, entrances, arches and bridges.

To prevent accidents and reduce safety risks, spalling concrete requires immediate attention and response. Mix one part Portland cement type 1 and one part fine sand by volume. Add water until the mixture is the consistency of thick paint, then brush it onto the wet concrete. Corroded steel can expand up to ten times its original volume, putting stress on the surrounding concrete.

However, despite the best intentions, concrete patch repairs often fail prematurely due to corrosion occurring at the periphery of the repairs. The concrete repair product is then sealed to ensure that spalling does not recur. Symptoms of concrete spalling are flaking, spalling and large chunks showing on the surface of the concrete, exposing the coarse, rocky concrete aggregate. Use the bull float immediately, but wait for the concrete to harden before using the edger and broom.

Belzona 4141 is a lightweight epoxy compound designed for concrete repairs to overhead and masonry structures. Common mistakes are adding too much water to the mix, to facilitate pouring; spraying the concrete surface with water, to prolong the finishing time; and not curing the concrete properly after installation. The type of repair and the work involved depends on where the concrete spall is located, how deep it is, whether it is on a vertical or horizontal surface, and whether there is any exposed rebar. Concrete repairs must be carried out in accordance with the European and British Standard BS EN 1504 for the repair and protection of reinforced concrete.

Concrete resurfacing is used to repair and revitalise concrete surfaces that suffer from things as minor as staining and light corrosion due to the elements, to more structural problems such as spalling. Another key factor to consider is the concrete mix, as excess water can also cause spalling.

Riley Ryan
Riley Ryan

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