What are ETA approvals for concrete anchoring?

30 Dec 2021

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ETA approvals for concrete anchors: what are they exactly?

Everyone who buys something expects a certain quality from that product. Whether it is a car, a coffee machine, a chair or a concrete anchor. It is usually impossible for a buyer to properly check the quality of a product before purchasing. This can be provided for with an approval or certificate: not the buyer, but an independent expert party determines whether the desired product meets certain requirements. This is done on the basis of fixed standards and assessment guidelines (BRLs).

Substantial loads can be exerted on post-placed (ie not 'cast-in') anchorages in concrete. Think of heavy fencing, stair constructions, balustrades, windmills and lifting constructions. It is not surprising that an anchor so 'critical' meets certain safety requirements.

In the past, these requirements were regulated nationally, but today European directives apply to them. If the anchor complies with such a guideline, it can be provided with a so -called ETA approval : a quality certificate that states that an anchor has passed a fixed test protocol for a specific application and has been declared suitable. Which test protocol such an anchor has gone through then determines the 'type' of the ETA approval. The abbreviation 'ETA' stands for 'European Technical Assessment'.

When is the use of an ETA approved anchor necessary?

If we connect all regulations and regulations from the ETAG (European Technical Approval Guidelines), the Building Decree and the CUR recommendation 25:2000, it can be concluded that an ETA-approved anchorage is mandatory when the following points apply:

The anchor is not temporary, but a permanent part of the structure. As an example: this applies to a balustrade, but not to push-pull braces.
The anchor is safety-relevant, which means that if the anchor fails, there is a real chance of major damage or even casualties. As an example: this applies to fire-resistant cladding in a traffic tunnel, and not to a kitchen cupboard.
An ETAG is available for the substrate in which the anchor is placed. As an example: this applies to concrete, but not to asphalt.

If all these conditions apply, then you are required to use an ETA approved anchor. If this does not happen, the person who places the anchor is in violation and in extreme situations this person can be prosecuted both civilly and criminally.

Different types of ETA approvals

There are about 25 'types' of ETA approvals for post-installed anchors, all of which are associated with their own test protocol. They differ in approvals per substrate (for example in brick or masonry) and in type (for example for single or multiple applications). An endorsement on an anchor, of course, only has value in that specific situation. In other words: an ETA approval has no value if it has been issued for the substrate brick and the anchor is placed in concrete.

Of the approximately 25 existing ETA approvals, five are the most relevant. The others are so rare that they are not considered in this blog.

Two concepts briefly explained

To understand the scope and relevance of the different ETA approvals, we first explain two concepts. It concerns the tensile zone / compression zone (also called 'cracked concrete' and 'uncracked concrete') and the concepts of single / multiple fastenings.

Trek zone
Let me start with what the tensile zone of concrete (or 'cracked concrete') means. Concrete is a material that cannot bend. When concrete is put under tension (it is 'pulled' at a tensile zone), cracking occurs.

Imagine a concrete bridge that sags slightly due to traffic or its own weight. At the underside of the bridge, the concrete is then stretched slightly: it sits, as it were, in the outer bend. This can cause cracks or fissures in the concrete at the bottom. This zone, where the concrete is thus pulled, is called the concrete tensile zone.

Pressure zone
At the top (the 'inner bend') of the bridge, the concrete is compressed. This is also called the pressure zone (also called non-cracked concrete).

It goes without saying that an anchor in the tensile zone has a harder time than in the compression zone, and therefore higher (ETAG) requirements are imposed on this anchor. That there is a pressure zone must therefore first be proven by means of a constructive calculation. Because a tensile zone is the least favorable situation, it may be assumed without calculation.

Single confirmation
With a single fixing , EVERY anchor installed is crucial for structural safety. In other words, if one anchor fails, there is a real risk that the entire fixture will fail, including any adjacent anchors.

Think of a hoisting installation with four attachment points: if one of the four anchors should fail, the other three anchors will not have sufficient overcapacity to absorb it, and they also fail (sometimes only after a while), causing the hoisting installation to fall over.

Multiple confirmation
Multiple anchors are based on a group of anchors, with a minimum of five. The construction has been calculated in such a way that if one anchor fails, the other four have sufficient residual capacity to absorb it. This includes cable ducts, suspended ceilings and piping.

The most important ETA approvals and their significance

ETA-1 approval . This is actually the heaviest clearance on an anchor. The anchor may be used in the tensile zone and in the compression zone of concrete, for both single and multiple fastenings. In some cases, such an ETA-1 approval is further extended with a so-called seismic approval, making it also resistant to vibrations.

ETA-7 approval . With an ETA-7, an anchor may only be used in the pressure zone of concrete (which must therefore be demonstrated in advance with a calculation), for both single and multiple fastenings.

ETA part 6 approval . This is a multiple fixing approval, often for female thread anchors or anchors with a relatively small drill diameter. These anchors may be used in both the tensile zone and the compression zone of concrete, but only for multiple fixings.

ETA TR029 approval . Where all previous (and subsequent) approvals are about anchoring in concrete, the TR029 is an approval for stone and masonry. No distinction is made here between tensile and compression zones. Both single and multiple fixings are allowed. Specific types of stone (both solid and porous) are always described in the approval, but the approval usually provides for deviating from this.

ETA TR023 approval . This is also known as the 'ETA approval for post-installed rebar '. With all previous approvals, the application is that 'something' is attached to the concrete or stone. A wooden or steel beam, a foot plate, a sunblind, a fence or the like. But the ETA TR023 is relevant for increasing the concrete structure itself.

In fact, concrete is attached to concrete. Think of widening a bridge, closing an elevator shaft, expanding a parking garage or home or retrofitting a balcony to an existing building. In these cases, reinforcement must be placed parallel to the reinforcement already present in the existing concrete, which then continues into the new part (for example the new balcony). In this way the construction behaves as a whole again afterwards.

How do you know which type of ETA approval your anchor has?

The concrete screws (SB2-PLUS) and through -bolt (TB1-PLUS) from Sympafix are only available with an ETA-1 approval. As a result, you never run the risk of using a product that has too low an approval. The same applies to the chemical injection anchors C100-PLUS , UC200-PLUS Ultrabond and the X150+PLUS .

But you can also find it on the packaging of all brands. If the anchor has an ETA approval, the manufacturer is obliged to state the ETA logo on the packaging. Under that ETA logo is usually the type, or else a unique number (eg ETA-17/0650). In the latter case, you can enter that number into your search engine.

Please note: ETA approval does not always apply to all available diameters or lengths. At Sympafix, for example, the TB1-PLUS push-through anchors have an ETA-1 approval, but this does not apply to diameter 6 mm. You will therefore not find an ETA logo on the packaging of this diameter.

Differences within the same ETA approval

Products and brands with the same approval (eg ETA-1) can still differ in important aspects. Compare it to a car: a car is only allowed on the public road in the Netherlands if it has an admission or type approval. However, all cars with such approval may not be allowed to do the same: for example, one may tow a heavy trailer, but the other may not.

And even though they may do the same, sometimes they can't. With a 4x4 Jeep you can easily climb a muddy hill, but with a 2CV the challenge will be too great. The RDW type approval therefore only indicates that a car has been approved for use on public roads. But there may be restrictions for one brand/type, which may not apply for another brand. The same story also applies to ETA approvals.

Back to the example of an ETA-1 certification, and let's take a syringe anchor / injection anchor there as an example. For convenience, we include two concrete examples: the Hilti HY200A and the Sympafix UC200-PLUS ULTRABOND . Both fast curing two-component injection anchors, both provided with an ETA-1 approval. Both may therefore be used for single and multiple fixings in both the compression and tensile zones of concrete. However, there are important differences within that certification, so that one can be used in a certain situation, and the other not. A few examples to illustrate:

In very severe frost, the temperature of the substrate can be below freezing. Hilti HY200A retains its ETA approval down to a substrate temperature of -10°C, where this is -5°C for the Sympafix UC200-PLUS ULTRABOND.
The permitted load-carrying capacity / bonding strength can differ (greatly). As an example, take an M10 threaded rod at 50°C/80°C ambient temperature. The Hilti HY200A has an excellent bond strength of 6N/mm² in this application. However, that of the Sympafix UC200-PLUS ULTRABOND is still 25 % higher. This difference can determine whether an anchor is or is not suitable for the application.
The approval of the Sympafix UC200-PLUS ULTRABOND provides that the injection anchor may also be used with a threaded rod of steel quality 4.6 and 4.8. At Hilti, a minimum steel quality of 5.8 is required, which in practice will often mean that 8.8 steel has to be used.
When it has rained on the construction site, the boreholes may be filled with water. The Hilti HY200A ETA certification explicitly prohibits the use of the product in water-filled boreholes; while the ETA approval of Sympafix UC200-PLUS ULTRABOND also remains in effect in water-filled boreholes.

There are, for example, more examples that in practice have a direct consequence for the validity of an ETA approval. It is therefore always wise to download the original ETA approval from the manufacturer's website and check whether the diameter used, drilling method, installation depth, environmental conditions (dry or wet drill holes and temperature), steel quality and of course the required load capacity correspond to the practical situation. You can of course also consult your manufacturer for technical advice. In that case, ask him to confirm or demonstrate the critical points for you in writing.