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Concrete Repair

27 October 2020

Do we ever really notice how many concrete structures surround us every day?

Most of us do not realise, in our evolving urban landscapes, how many concrete structures facilitate our everyday activities. They are everywhere, in every form, shape and size; working to support our needs. Yet, even in its strength and durability, concrete needs to be maintained. Just as we are affected by the stresses and strains of everyday life, so too is concrete subject to deterioration over time.

How do we know this? Sika has more than 100 years’ experience on large and small concrete projects, all over the world. We have documented successful project references dating back to the 1920’s. We are proud that Sika is the company with the most concrete repair project awards worldwide, with 84 ICRI* awards in the last 16 years.

To start at the crux of the problem, why does concrete deteriorate? Deterioration of concrete may occur due to corrosion, structural damage, water infiltration, seismic activity or a multitude of other reasons. Years of research, coupled with decades of practical experience, have enabled Sika to develop a fully comprehensive solution to restore and rehabilitate concrete structures.

Why do we repair? We repair concrete to address defects, restore structural integrity, restore aesthetic and geometric appearance and ultimately restore durability. A wide range of products are needed for the concrete repair process, and Sika South Africa have developed the complete product solution.

Most concrete repair processes would start with a bonding primer and corrosion inhibitor.

Corrosion protection and bonding primers are used for bonding concrete repair mortars to existing cementitious, or steel, substrates and provide additional corrosion protection to reinforcement steel. This is especially so in areas of low concrete cover and in the presence of chlorides. Exposed reinforcement steel bars should be properly prepared and protected with anti-corrosion slurry.  SikaTop® Armatec®-110 EpoCem® is the primary rebar protective coating for concrete repair.

The next step is to select an appropriate repair mortar. Mortars are specifically designed for restoring or replacing the original profile and function of the damaged concrete. They help to repair concrete defects, improve appearance, restore structural integrity, increase durability and extend the structure’s longevity. Sika concrete repair mortars are suitable for restoration work, repair of spalling and damaged concrete in all types of structures including buildings, bridges, infrastructure and super-structures. Our latest edition to our repair mortar range is the Sika MonoTop®-412 NFG. This product differentiates itself as a 1-component, polymer modified, fibre reinforced, low shrinkage structural repair mortar with Sika’s world-renowned Sika® FerroGard® corrosion inhibitor. That is a 3-in-1 advanced product solution.

Sika MonoTop®-412 NFG has unique properties that allow it to be an excellent wet-spray mortar. This application method improves the compaction of repair mortar and increases the application rate of the product.

The other quantifiable factor is that the Sika MonoTop®-412 NFG is a 1-component product as it does not require a bonding primer even when manually applied, it is a 3-in-1 advanced repair mortar, resulting in further time and money savings. Our repair mortars all come with either a class R4 of EN 1504-3 or Class R3 of EN 1504-3 standard.

Prior to coating or levelling of concrete, special mortars are necessary to fill the surface pores or “honeycombs”. Sika’s solution for repairing minor defects, such as repairing pores and honeycombed concrete, is the Sikagard®-720 EpoCem. It is a normal setting, three-component, epoxy modified, cementitious sealing and protective mortar.

Sikagard®-720 EpoCem can be used as sealing mortar (0.5 – 2.0 mm) on concrete, mortar or stone. It can also be used for repairs to fair faced concrete in chemically aggressive environments, or as a pore sealer on horizontal and vertical surfaces. In addition, it also provides a temporary moisture barrier (2.0 mm).

Once the concrete repair process is complete, it is imperative that a concrete protection product is applied.

The most common causes of steel reinforcement corrosion in concrete are carbonation or chloride ingress with water. Understanding the root cause of steel corrosion determines the most effective repair and protection strategy. Sika provides a full range of products to prevent further corrosion of steel reinforcement, by properly protecting the concrete around it. Our corrosion management systems allow flexibility to select the most cost-effective and suitable solution for any project. Sika® FerroGard®-903 Plus has innovative technology that not only delays the start of corrosion but reduces the corrosion rate when it occurs. This results in an increase in the service life of a reinforced concrete structure, making it the product of choice.

At Sika South Africa, we pride ourselves in knowing that our advice and support to our customers is second to none. We take the full journey with them. From concept, to successful completion on site, providing only the best products necessary for the task. Entrusting Sika, a supplier with over 100 years’ experience, ensures your concrete repair will stand the test of time. We have concrete evidence!

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