Elastomeric supports:
The basis of success

Within all of this, elastomeric supports are the strong component that Casesa specializes in. David, can you explain what elastomeric supports are to someone who doesn’t understand this, a complete novice in all of these matters?

Well, I’ll try to explain it in a simple way so that you can understand. Elastomeric supports are rubber pieces that absorb vibrations and expansions in structures, whether they are metallic or made of concrete or any structure that carries a load. Let’s say that their function is to protect the joints between different structures made of different materials. For example, an elastomeric support for an air conditioning unit in a large shopping center, a bridge, a building—anything that serves to absorb vibrations and movements.

You can check all our RUBBER SOLUTIONS on our home page

The main applications, in our case, are primarily for heavy structures such as highway bridges, large-tonnage metal structures, and also, a very important use is for prefabricated warehouses, the concrete structures that are widely used nowadays, essentially that.

The functioning of the support, being an elastic material, is what allows it to absorb movement. By utilizing a combination of steel and rubber in its structure, elastomeric supports effectively absorb movement by utilizing the elastic properties of rubber in all directions. Depending on the design of the support, it can absorb larger or smaller movements in different directions. The supports are designed according to the forces they will encounter, whether they require a specific design for earthquakes, known as seismic supports, which incorporate additional layers of steel and rubber. In essence, each application has a specific design to effectively absorb the intended movement.

Are constructions being carried out or is it not necessary here because we are not in an earthquake-prone zone?

In Spain, there are regulations that mandate seismic safety measures in areas at risk of earthquakes. Yes, it is mandatory. For example, in the Lorca area, you cannot construct without implementing seismic-resistant support systems to prevent the propagation of seismic waves. In other areas, it may not be obligatory, but all newly constructed large-scale structures, such as major shopping centers, warehouses for Mercadona, Amazon, and other similar giant warehouses, incorporate rubber supports between their supports. Bridges, of course, have been using such supports for many years. In general, the regulations are quite well adhered to in Spain, and supports are installed in almost all necessary locations according to the regulations.

Do you have any idea how they do it? Then, when they purchase elastomeric supports from you and take them to Structure X, how do they install them?

Well, it depends on the type of support. Bridge supports usually have a plateau that is custom-made, as advised by the technical architect or engineer, and the support is placed on that plateau. If the support includes a metal structure, it often has studs or is welded onto the bridge. As for the less critical supports, such as those for buildings, typically the rubber piece is placed on the area where the beam will rest or it has holes and the beam passes through the center of the support to prevent movement, or it is simply glued in place. In 90% of cases, the installation is straightforward, usually involving the application of an adhesive to prevent slippage, welding, or simply placing it on top and relying on its weight. In other words, the installation of elastomeric supports does not involve much complexity; it is a matter of placing them in their designated positions.

From what you’re telling me, you directly communicate with engineering firms or architects who request custom-made products from you. If it’s for a specific bridge, they provide you with the desired specifications, such as the dimensions, the number of rubber layers, the inclusion of metal, or any other requirements, and you have no problem creating the requested product.

Exactly. We work directly with engineering firms or architectural consultants who specialize in offering complete bridge solutions. They provide us with the design specifications for the required support, and we manufacture it according to their provided design. In some cases, we assist our clients who may not have a clear understanding of the specific support they need by utilizing our external engineering department. In this way, we provide them with the necessary support and guidance throughout the process.

Within all of this discussion about construction, bridges, and buildings, you must have some clients dedicated to these fields who are large-scale clients. Because typically, these are not small companies.

Yes, indeed. Over the years, we have established relationships with major clients in the industry. We work with large Spanish construction companies, such as Ferrovial, ACS, Dragados, Constructora San José, FCC, ACI, and many others. Additionally, there are significant construction departments within engineering firms, such as Mecanogumba, Mekano4, and Trelleborg, who are involved in construction projects on a large scale.

Let’s see, I’m not an expert in the technical department. I’ll try to give you a simple explanation of each one. We have two types. First, there are the un-reinforced supports, which do not have a metal core, that’s why they’re called un-reinforced, and they are used for small movements. Then there are the reinforced supports, which have a metal core. The type of support is determined by the auxiliary steel elements that the support contains.

Type B is a support that is a steel and rubber sandwich, with the steel inside the support and not visible. The surrounding part is all rubber, whether it’s a rectangle, a square, and you only see the rubber, but inside there are layers of rubber and steel.

Then there is type C, which is the same as type B but with additional layers of steel either on top or at the bottom, providing support for welding or introducing bolts into the beams.

Next is type five, which is similar to type C, but instead of smooth plates, it has embossed plates. What does embossed mean? It means that the steel has a pattern so that when you place it in the structure, it doesn’t move.

Then there is type D, which are the supports with Teflon, used to move large structures, such as bridges, but for temporary purposes. They allow for sliding, that’s why they have a layer of Teflon. These elastomeric supports are not permanent.

For moving a cable-stayed bridge, for example, there is a construction system that slides on supports of this type.

Then there are the anti-seismic supports, which have many more layers of steel and rubber, and they also have a lead core, etc.

The supports can be manufactured using different types of rubber as well. For example, in the United States and America in general, they comply with a regulation and usually use chloroprene. In Europe, natural rubber is more commonly used. So, different materials are also used, and the steels come in different grades, etc.

You’ve already mentioned that it’s the technical departments of engineering, architecture, or others who inform you about the type of elastomeric support required. But how is that type of elastomeric support selected for each specific application?

Well, primarily, the selection of the support depends on the force it needs to withstand and the specific movements it needs to resist. The architect considers the weight that the support must bear, which is crucial because the support needs to be accurately defined based on the weight it can handle and the movements it can endure. A miscalculation in selecting the support can render it ineffective.

One of the most important factors to consider is that the support must be perfectly sized according to the loads it will bear. When it is installed, it should be aligned and flat on the supporting surface. There should be no gaps or spaces where you can insert a finger or encounter any similar issues that have occurred in poorly placed supports beneath a bridge. It is essential for the support to have full contact with the supporting surface throughout its entire area.

Now that you mention that sometimes a support may fail, what tests and quality controls are conducted during the manufacturing of elastomeric supports?

We have been operating within the ISO system for a long time, which helps us maintain traceability from the moment the materials enter our warehouse until the finished product is sold to customers.

It is essential to conduct material control, so having tests for the materials used in the manufacturing process is crucial. We perform mechanical tests, such as tensile strength and force tests, when the support is finished. Additionally, we manufacture these supports with the CE marking, which requires us to conduct specific tests and annual audits to ensure certified quality for the elastomeric supports.

I understand that these mechanical tests you mentioned are conducted using specialized machinery in your own facility, and every product or component undergoes these tests.

Well, actually, there are different ways to approach this. Until about 15 years ago, we didn’t have our own laboratory, so we outsourced the tests to external laboratories, of which there are several in Spain that can conduct the desired tests. However, if you get involved in the CE marking certification for different types of supports, it becomes impractical to rely on external testing. You need to be prepared.

Therefore, we invested in specific testing machinery a few years ago, and yes, we have it within our factory. We conduct all the necessary tests, following the frequency requirements (e.g., testing one out of every 400 supports of a certain type). The results are traced and documented. However, depending on the type of customer, they may demand external tests to validate the results obtained from our in-house facility.

To understand it easily, it’s like having fruit that you’ve inspected and tested, but you also want an external test to ensure the validity of the results.

So, yes, we conduct our own tests, but sometimes customers, depending on their requirements, request external tests to confirm the results.

And you mentioned earlier about possible failures. What is the typical service life of elastomeric supports and what factors can affect it, causing it to degrade earlier or last longer?

Well, we are not legally obligated to provide a specific service life for the support. However, the service life of a well-manufactured and properly installed support should be quite long. We are talking about several decades, and ideally, it should last around 100 years. That’s what a well-manufactured support should last, although it may not be explicitly guaranteed for that long. However, there is a minimum requirement of ten years. While there is no implicit warranty, there is an explicit expectation in the market that supports should last for a considerable time. If you have to replace or discard a support after just ten years, then you are not doing well. The minimum lifespan of a support should be significant. In our experience of 20 years in manufacturing, we have seen supports that have been in place for years. For a support to function properly, it should be optimally used for 50 to 100 years without failures.

Just a few years ago, we encountered a situation where supports that had been installed in a bridge in Mexico were failing after just one year. It turned out that the manufacturer had used poor-quality steel and rubber materials. They falsified test results by providing everyone with photocopies of the same report or changing the dates. It was a disaster, and it cost them a significant amount of money. They installed the supports, and after a year, the bridge started sinking, so they had to find an alternative solution, which we provided. Mexican auditors came to verify and ensure that we used good-quality materials. When something like that happens, the manufacturer responsible for the failure won’t likely get another chance because they ruined their reputation. While risking lives over a rubber support is not ideal, it is essential to use high-quality materials. We strictly adhere to maintaining the quality of materials we use.

Now that you’re talking about materials and I’ve heard that you can add more rubber or more sand. Elastomeric bearings are said to be made of rubber and steel, depending on the type. But how is rubber manufactured? Because you manufacture the rubber yourselves and you can do it in different ways. I suppose that’s how the whole manufacturing process works. How is rubber produced?

In the world of elastomeric bearings, the rubber compounds are usually purchased pre-made. There are approved Spanish manufacturers who provide the desired rubber compound according to your specifications. So, we outsource that part. We purchase the pre-made compound to use in the mold, for example, for the bearings. We have previously tested and approved a specific formulation, which remains consistent and unchanged over time. However, we are not the actual manufacturers of the compound. We don’t determine whether to add more sand or rubber. There are variables such as the origin of the neoprene or natural rubber, which may differ from one batch to another. For instance, if the neoprene comes from Kenya but is temporarily unavailable, it may need to be sourced from Colombia, resulting in slightly different properties. In such cases, the compound manufacturer adjusts the composition to ensure that the values and properties remain consistent. By receiving and using the correct compound, we ensure that it complies with the necessary standards and regulations for the specified application.

And the last question I have about elastomeric bearings. Tell us an anecdote about some installations that you have had that may be interesting or memorable for some reason.

Well, we have had experiences here in Spain. The truth is that, for example, when we started with elastomeric bearings, the way we manufactured them was very different from how we do it now. Before, about 15 or 20 years ago, we made all the bearings for the M50, and you would come across things that would be impossible to provide now. For instance, there was a bearing that had a metal plate attached to it, and they would perform the pen test, which was a curious thing that, well, we don’t do anymore, but they used to do it. The pen test involved running a pen along the edge of the bearing, and if it made a sound, it meant that the steel was exposed. Of course, they would tell you it wasn’t the case.

And then, especially in other countries, that’s where we have had more anecdotes. For example, in Algeria, on some viaducts, they called us because the bearings were in poor condition, and as I mentioned earlier, you would go there, and it turns out you could put your whole hand underneath the bridge. So, it wasn’t that the bearing was faulty, it was just poorly installed.

And then there’s Pakistan, where we also had bearings, and they called us because they had issues and such. We went there, and it turns out they placed a general right next to you, and you can see that something is wrong. You calculate the bearing, but since the general told you to say it’s fine, you have to say it’s fine, and that’s it. Whether it’s fine or not, it’s fine, and then you come back here, they withhold the payment that corresponds to you, and that’s it. That’s how it goes.

Based on what you’ve told me about other countries, I hadn’t asked you yet. Which countries have you already provided your services to? In which countries have you installed structures such as buildings or bridges?

Well, we directly sell to countries, especially those that are relatively close. For example, Southeast Asia, that whole area, not so much because they are well supplied by Japan, the United States, and such. But Russia and all the countries, for example, Turkey, all the neighboring countries, North Africa, South America, we also sell quite a bit to Europe, both directly and indirectly. Well, more or less, excluding China, Japan, Australia, all these areas that are a bit far for us, the United States, Canada, there’s a lot of work, but we don’t sell there. But yeah, more or less, it’s the rest of the world.