EAD, ETA & CE - WHY IS THIS RELEVANT FOR UHPC?

How we have decided to proceed with the documentation of our products

DOCUMENTATION OF ULTRA HIGH PERFORMANCE CONCRETE

In one of our previous posts: Do we really a need another guideline for Ultra High Performance Concrete?, we mentioned that Hi-Con has applied for an ETA, and now we are ready to add a CE marking to our balcony elements. It took a bit longer than expected, but in the following post, we will explain a little more about what this means, why we decided to do this, and how the process has been.

Before you dive into the post, we want to point out that this blog post does not contain much information specifically about Ultra High Performance Concrete—it is instead a description of how we have decided to proceed with the documentation of our products and what was necessary.

You can read more about Ultra High Performance Concrete here:

What is Ultra High Performance Concrete?

WHY DID WE DECIDE TO GET CE CERTIFICATION?

As described in the Construction Products Regulation (CPR) for the EU, it has long been mandatory for manufacturers of construction products to produce a Declaration of Performance (DoP) and apply CE marking to one of their products. This applies if they follow a harmonized standard, as they automatically comply with the EU directives for safety and health. In this case, the CE marking indicates "fitness for intended use." In our case, we produce elements in Ultra High Performance Concrete (UHPC), and if we want to design according to this, we have no harmonized standard to follow.

This means that we have to document our solution on a case-by-case basis—and we are not allowed to put a CE marking on our products. In some instances, this has given us greater freedom in how we choose to do things, and after the first few projects were carried out in Denmark, the lack of CE marking—or standards we could follow—has not really been problematic in Denmark. The first balcony and staircase projects were carried out in 1997, and since then, our Development Manager, Bendt Aarup, cannot recall any projects where we were disqualified because we did not have the correct documentation.

The same has applied to projects in Sweden and Norway, where our documentation is "accepted" as equivalent to a standard. In the Netherlands, it was a bit different, as we had to go through a very thorough process on the first few projects — including full-scale tests and a "second opinion." In this case, it was a thorough evaluation of the project by Professor Walraaven from Delft. After that, there have been no further requirements in the Netherlands, and the approval by the authorities is very similar to that in Denmark.

One of our first CRC balcony projects from 1998

In some countries, however, it is very clear that CE marking would likely be very beneficial for the sale of our products. When we provide our own documentation for a project, the engineer must assess and determine whether this level of documentation is sufficient—in cases where the product has a CE marking, it is unnecessary for the engineer, owner, or building authorities to evaluate whether our balconies are suitable for installation, as this has already been done by another party. This way of thinking has been particularly evident in Finland and England. In London, we had a project where our solution was approved by the parties we had in mind: the owner, the engineer, the architect, and the building authorities, BUT the insurance company then decided that they would not insure the building if the balconies were not CE marked! We have quite often explained our design methods and material properties—but rarely to an insurance agent. In this case, the interest in understanding our explanation and making a decision in favor of our product was not really there. Unfortunately.

Currently, we are looking at a few projects in Germany, and it is another market where we hope the CE marking will be useful—although we expect there may be a need for additional tests in the form of a special approval.

Previously, we have often been asked why we do not obtain national approvals—for example, from the British Board of Agreement—but we have been reluctant to do this, as any approval would typically be limited to a specific product and specific dimensions. The CE marking is different because it covers a larger market and has a broader scope. With the hope that such a certification would facilitate "acceptance" in our new markets, we decided to start the process. We began the process in the spring of 2014—and did not expect it to take nearly five years.

WHAT ARE THE REQUIREMENTS FOR CE CERTIFICATION?

If you comply with a harmonized standard, the steps towards CE marking can be relatively straightforward, but since there is no relevant standard for our material, we had to take a different approach. Another option was to CE mark a product based on an ETA (European Technical Assessment) if the product is not fully covered by a harmonized standard. Therefore, we had a conversation with ETA Denmark about obtaining one of these and discovered that an ETA required another document—a European Assessment Document (EAD).

An EAD describes the methods and criteria for assessing the performance of a construction product, and an EAD is adopted in cooperation with the manufacturer, the European Commission, and the TABs. TAB stands for Technical Assessment Bodies, and there are currently 35 of these institutions responsible for the technical assessment of precast concrete products—this organization is called EOTA. That these TABs—involved in both EAD and ETA—include VTT from Finland, DIBt from Germany, and BRE and BBA from England was particularly interesting to us, as they represent markets that have specifically requested some form of certification.

Instead of looking at our certification "country by country," we had a chance to be assessed by representatives from all our targeted markets and address any comments they might have at the same time. A complete list of TABs is shown here.

We had hoped to get a general ETA for our material, but we quickly discovered that the ETA and EAD had to be based on a specific product and not just prefabricated elements produced in CRC. We chose balconies in CRC as a starting point and then began to put together an EAD in collaboration with ETA Denmark.

EAD AND ETA - WHAT SHOULD THEY INCLUDE?

Since it was us compiling the EAD—in collaboration with ETA Denmark—we had many options regarding what to include, and apparently, we chose the complicated route.

The EAD outlines the documentation methods and acceptance criteria for a construction product and must cover the essential characteristics. What constitutes "essential characteristics" is open to interpretation, and we could perhaps have settled on a few parameters like compressive strength, tensile strength, and water permeability. However, our concern was that even if you have a UHPC product that meets these requirements, you could still have a poor product. We wanted to provide a description where the producer gets a product suitable for use if all these requirements are met. So, in our case, the EAD includes an extensive list of essential characteristics that we consider important for performance (examples are compressive strength, form of stress-strain curve in compression after maximum load is achieved, stiffness, ductility, tensile strength, creep and shrinkage, freeze/thaw resistance, carbonation, fiber distribution, chloride penetration, and fire resistance). Additionally, design calculations must be verified through full-scale tests.

After the EAD was accepted by the European Commission (in May 2016), the next step was to prepare an ETA, which was then assessed based on the EAD. While we already had many of the test results, additional tests were still necessary to document the balconies. For instance, we have conducted extensive tests on high-temperature behavior over the years, but these tests were typically carried out at universities. Since we needed a classification report, we had to conduct a new test at a laboratory accredited for fire testing of load-bearing structures. The additional tests and compilation of all documentation took another year, but in May 2017, our ETA was accepted. The ETA is only 13 pages, but hundreds of pages were submitted to ETA Denmark as documentation annexes. After this, we "only" needed certification from Dancert to CE mark our balconies.

CERTIFICATION PROCESS

Obtaining an EAD and an ETA, and getting them ready for use, took significantly longer than expected—and the same turned out to be true for the certification. We chose Dancert as our certification body, and their first step was to receive certification themselves—so they could certify based on the EAD we had developed in collaboration with EOTA and the European Commission. Once this was in place, we had our first visit from Dancert to review our production and our Factory Production Control (FPC) based on our EAD and ETA.

We thought our quality control was quite good, but it turned out there were several things we hadn't considered carefully enough. Issues such as: Are all our suppliers CE-marked? Did they have the correct information on each delivery? Traceability in general was one of the issues that took us some time to get fully under control. One result of this—as I mentioned in a previous post—was the need to install two large fiber dispensers so each batch report shows the exact amount of fibers used. The batch reports were also slightly adjusted to indicate several key parameters for our mixtures (w/p ratio, cement/silica ratio, fiber index). If these key parameters are not within certain limits, it now triggers an alert for the mix.

Certifying a UHPC material based on a rather complicated EAD was new for Dancert, which also led to some explanation and discussion back and forth about what was important for the certification. This could involve discussions about why ASR (Alkali-Silica Reaction) is not a major issue when you have a high pozzolanic content in your binder, what the minimum tensile strength for a steel fiber should be depending on fiber length, or the reasoning (and documentation) behind the limits we have set on key parameters in our mix. But after many documents—and many discussions—we finally received our certification and have been able to CE mark our balconies since March 18, 2019. It has been a long process, but we have learned a lot along the way, and it has left us with a better product—and certainly better quality—than when we started in 2014. We also had to provide a product declaration (DoP) for the balconies.

Compared to other concrete producers, our DoP is somewhat complex, and many more parameters are listed. We have been asked why we don't limit it to just a few parameters to make it easier for ourselves (which certainly would have reduced the time it took from the start of the EAD to the final certification), but we actually did this on purpose. We believe ultra-high-performance concrete (UHPC) is complex, and many very different properties combine to create a good product. We have already seen examples where other producers—not familiar with UHPC—have copied some of our slender designs. They have copied our dimensions and produced elements based on a 100 MPa concrete. This is not difficult to do, but if you do not provide the correct ductility by including steel fibers—or if you do not consider the risk of explosive spalling during fire exposure, there is definitely a risk involved in structural applications. We do not mind competition (there is not much we can do about it), but we want them to do it the right way by realizing that compressive strength is not the only property you need to consider for a reliable design in UHPC for projects like the one below.

Our CE marking is very new, so we look forward to seeing how it is received in the market—or if it has any effect at all. If the CE marking facilitates the approval of our balconies, we will certainly consider doing something similar for other products such as stairs and facades. Hopefully, it will be a shorter process next time, as our EAD, ETA, and CE marking mostly deal with the approval of the material—very little is actually product-related.