This is a transcript of the Belzona “Solve it Session” webinar conducted on 27th March, 2018. You can watch the webinar recording here:
Belzona Solve It Session: Concrete Solutions from Floor to Ceiling
The first point to discuss is the damage mechanisms we find throughout industry with concrete. It Is a widely used material, which has many applications.
Under a compressive load, concrete is one of the best building materials around. However, this does not mean it is completely invulnerable to damage. Much like the deterioration of steel through rusting, moisture has many detrimental effects on concrete.
This is where the moisture inside concrete freezes and expands, causing a big issue. The cyclic loading caused by the constant expansion and contraction can break the concrete down, eventually resulting in failure.
Freeze thaw damage to a effluent tank
Another type of damage which is incredibly common is spalling/cracking of the substrate. This can be caused by numerous factors, but the main reason is almost always moisture. How many times have you been inside a structure made of concrete, and not seen ANY cracking or damage at all?
Unfortunately, it is a bit of a paradox. Moisture is required in order for concrete to cure correctly; there is an excess available within newly laid concrete. But it is also the main reason it fails! Too little moisture can cause it to dry out. Just the right amount can cause carbonation to occur.
Carbonation is a major issue as it is not as easy to predict as other types of damage. We need a few things for carbonation to take place – moisture, CO2 and porosity. With these, the concrete breaks down over time, eventually causing it to fall away from the surface.
Abrasion is a major issue in areas which involve heavy machinery or transport. The heavy-duty materials used, and repeated contact causes concrete to wear over time. This allows moisture to penetrate the surface, leading to some of the above problems.
As concrete is alkaline by nature, a change in the pH can play havoc with the binders contained within the material. This disrupts the mechanical properties of the product, ultimately leading to failure over time as these properties become reduced.
Concrete is known for its fantastic compressive strength. It can hold tremendous weight over a large area without any mechanical failure. The problem comes when this force, which is normally spread over a sizeable area, becomes concentrated. This is caused by impact. The force can be enough to fracture the concrete, or in most cases, damage it on a structural level. Much like abrasion, this can be a repeating process.
Like-for-like concrete repairs are often favoured. But these can struggle to adhere to the existing substrate. Besides, what’s to stop the same damage from happening again?
Belzona has created a range of 100% solids epoxies for mortar repairs as an alternative to traditional rebuilding. These epoxies are designed to restore concrete structures, protecting them and prolonging their lifetimes. And rather than trying to individually solve every one of the above issues, Belzona have created a just handful of versatile systems, which can be used to treat an infinite amount of problems.
But how do these materials compare to like-for-like concrete repairs itself? To test this, Belzona has created the following video:
As well as our video, we also have a lot of real world examples of areas where Belzona was used to repair damaged concrete. Belzona has over 500 case studies where our 100% Solids Epoxies and coatings were used on concrete.
An independent online case study library – industsolutions.com – found Belzona to be the fourth largest provider of case studies in the world. This is how dedicated Belzona is to sharing information about their applications.
Now we’re going to examine four case studies which really highlight some of the features from the above “Belzona vs. Concrete – Put It to the Test” video.
This case study is a very good example of the type of damage found all over the world – large, industrial areas which are built primarily out of concrete.
This concrete is actually 40 years old, inside of a freezer in a meat factory. If left untreated, this could cause significant problems for them in the future. For repairing it, the customer faced a few issues:
- They required 24/7 forklift access to the area
- There were multiple locations across the factory which required treatment
- They only had 3 days to complete the application
The issue with using concrete in this case would be down to the cure time – up to 28 days in order to achieve a full mechanical cure. Obviously, this would have meant they were out of the 3-day window given by the customer.
Therefore, the fast-curing Belzona materials chosen were:
- Belzona 4154 resins + aggregate to bulk fill
- Belzona 4111 overlay for optimal properties – compressive, tensile, impact and general chemical resistance
This application required little in the way of roughening, as the surface had an adequate roughness to accept the Belzona materials. This means that there was no requirement for heavy preparation equipment, eliminating HAV values which are normally an issue when roughening a concrete surface.
An SX/EW plant (solvent extraction and electrowinning) is part of the process involving the leaching of copper ore heaps through the use of dilute sulphuric acid. This is then taken away to the SX/EW reactor via a drainage system. The solution contains lots of impure copper (anode), so cathodes are used in the process (pure copper) in order to attract the copper ions via electrolysis.
The problem with this is:
- There are chemicals involved, and
- The solution is not cold – it was almost 50°C (122°F) in this job
The tanks were leaking as a result of continuous use and concrete breakdown, and the rails which held the cathodes in place began to fail due to the heat transfer through the cathode itself.
Now, it seems like quite a complicated issue. Fortunately, the repair was simple.
Belzona 4111 was applied to rebuild the concrete and restore it to its original profile. This then allowed Belzona 4341 (designed for hot, inorganic acids) to protect the surface from further damage. This allowed the cells to continue in use for many years to come, and the success of this application was all down the surface preparation.
At a church property, a balcony was seeing cracks due to its natural movement over time. These cracks were allowing water to seep into the substrate. Originally, the client tried to repair the balconies with a sand and cement mixture. However, the adhesion of these materials was simply not good enough, and they failed.
The client wanted a solution which would be long-term and cost-effective, so turned to Belzona. For this application, the screed solution was specified. Belzona 4131. This was because of its outstanding adhesion and ability to feather edge. This was used to repair the cracks.
Then, to fully waterproof the balcony, Belzona 5811 was coated on top. This also left an aesthetically pleasing finish on the balcony.
The final case study highlights Belzona materials’ lightweight properties wherein the chosen system was Belzona 4141. It can repair vertical damage of up to 127 millimetres and overhead damage up to 76 millimetres, with minimal or no former usage.
These properties made Belzona 4141 an ideal solution for this case study at a severely damaged office building, where hundreds of repairs were needed. At the office, literal chunks of concrete were falling down from the façade, making it a massive health and safety risk. A full repair was necessary, which Belzona was able to provide with just the one product.
Over 300 vertical and overhead repairs took place around the building over three months of working weekends only. Then the office was completely restored, with minimal disruption to its everyday operation. A final reason Belzona 4141 was chosen was because it can be tinted. In this instance, the red tint ensured the system blended in to the office’s façade and these repairs were barely visible.
All of the products used within these case studies have their own individual merits, such as the lightweight Belzona 4141, or chemically resistant Belzona 4341. However, there are many features shared by them as well. For example:
- Most of the products are 2 parts, with easy to follow mixing ratios
- No volatile components are present
- Good mechanical strength
- Magma polymers can be feather edged
- They are easy to use and quick to cure