23 November 2020
When we took a look back at the blogs we’ve shared over the years, one thing became apparent. When we talk about flooring we look at products and their suitability and why one option may be better than other options, but when it comes to structural repair, we share a lot about the approach to take, things to consider, tips to use and so forth, but rarely do we get under the hood and look at what is involved with treating the cause.
We know from our previous blogs that spalling and water are problems need to be resolved, and we talk about the need to strip back the affected area, but rarely do we look at the process of treating rusted steel.
So, in this blog, we thought we would discuss the importance of stripping back the affected concrete, exposing the steel and then taking steps to ensure structural strength is maintained. Whether this is through replacement of the existing reinforcement and new concrete, or the treatment of the in-situ steel, we will discuss what your options are and what needs to be done to protect the steel from ongoing corrosion.
Steel Corrosion in Detail
In any environment, the process of deterioration of materials caused by chemical, electrochemical or other reactions is termed as corrosion. In the case of steel, corrosion is an electrochemical process where iron (Fe) is removed from the steel being corroded and is dissolved into the surrounding solution; at this point it then appears as ferrous ions (Fe+). The resultant formation of rust—a red/orange coating on the surface of metals is just but part of chemical process of corrosion and can only affect iron and its alloys.
Theoretically, there are a myriad of reasons why steel corrodes. For example, when steel reacts with other substances like oxygen, hydrogen, dirt, microscopic organisms such as bacteria or even electrical currents, it can corrode.
It can also happen when steel is set under too much pressure causing it to crack.
The corrosion of steel has considerable technical, financial and societal impact. It constitutes the main source of untimely aging and deterioration of reinforced-concrete structures worldwide. It directly affects costs of maintenance, repairs and rehabilitation and, indirectly affects operations, insurance, and saleability.
Ordinarily, concrete shields reinforced steel from corrosion due to its alkalinity. To hinder the development of corrosion and rust, a thin defensive layer of stable oxides is formed on the surface of the steel. This is basically due to the high pH value of concrete. At the point when this defensive layer of stable iron oxides is compromised by the impact of a strong corrosive environment, rust appears.
When steel reinforcements corrode, it will increase its volume. This results in propagation of internal tensions and cracks in the concrete and consequently peeling, more moisture and an ongoing cyclical problem.
Corroded steel alongside broken sections, poses numerous safety risks that could do any or all of the following:
- Compromise and put at risk a building’s structural integrity.
- Rust can destroy the outside of your steel as well as weakening it, prompting cracks and broken sections.
- Forges and propagates the conditions for further corrosion of the remaining steel reinforcement.
- Decreases the structural element’s resistance to fire.
- Lead to internal leaks as water has a pathway insideMay create problems to the appearance and aesthetics of a structure.
So what is the solution?
Once the cause of your rust and corrosion is determined, the affected concrete must be stripped back and removed with the corroded steel rods completely exposed and uncovered. Should there be early indications that the steel sections are experiencing rust, it is best to act upon it at the earliest opportunity.
Depending on the degree, extent, and level of corrosion, rust must then be removed from the in-situ steel. This can be done through using rust-removing solutions. These chemicals would be able to remove any signs of rust on your steel section. The steel can then be grinded, scrubbed, or any number of standard methods.
Appropriate tools such as wire brushes, sand blasters, water blasters, or a myriad of other acceptable tools should be used, returning the steel to its former state. However, there might be extensive damage necessitating the replacement of the existing steel reinforcement and new concrete to ensure structural strength is maintained.
Protecting Steel from Corrosion
With the above completed, attention should turn to what needs to be done to protect the steel from ongoing corrosion in the future. A good preventive measure that can help shield your steel sections and parts from rust is by applying a protective coating, a good example is rust-resistant paint or other coatings.
Rust-proof steel coatings put a protective layer on the metal surfaces that represses the contact between the metal and corrosive elements. Commonly, they are applied on the metal surface to forestall degradation caused by moisture, oxidation, salt spray, or chemical exposure. There are a few coatings that also guarantee protection from abrasion.
Corrosion resistant coatings are one of the most favoured strategies utilised for shielding metal from the destructive impact of atmospheric and environmental factors. These coatings add an additional layer providing additional protection against elements that cause rust, hence prolonging the life of steel parts and sections.
Steel and concrete work in harsh conditions, and coatings improve the chances that they will withstand the elements for the longest conceivable life span. But it is worth remembering it is normal for any structure to experience some type of corrosion in spite of the sort of materials utilised.
We should also point out, it is also critical you consider the utilisation of heat-resistant coatings that offer protection to components that may be exposed to extreme temperatures or severe temperature fluctuations variances. These coatings are designed and made to secure components against heat whilst operating to high-performance levels in challenging environments.
These heat resisting paints and coatings are likewise needed to convey superior performance humidity resistance and anti-corrosive protection against fluids including water, oil and petroleum, salt, gas, rust and chemical solvents.
We know there is a lot to take in, but the good news is, if you have concerns regarding your building and potential steel corrosion, we have the expertise, skills and team ready to help you. Let’s have a chat.CONTACT US
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