Technical Note 4

CE Marking of GCCMs

This Technical Note considers the importance of ensuring that GCCMs and GCCBs* are correctly CE marked for their intended use when using the European Economic Area (EEA) and the United Kingdom

Concrete Canvas Ltd products are the first and only GCCMs and GCCBs to be CE marked for use in Surface Erosion Control applications.

It is the duty of the manufacturer, the importer and the suppliers of geosynthetic products to ensure compliance and the Construction Products Regulations (CPR) provides an enforcement and penalty regime to ensure that construction products placed on the market adhere to these standards.

Figure 1: The change of GCCM properties from flexible to rigid on curing means that when assessing GCCM properties, appropriate test methods should be used to determine the cured, in-service GCCM cementitious layer performance

The Problem

GCCMs and GCCBs are unlike most geosynthetics as their properties change from flexible to rigid on hydration. This is because GCCMs/GCCBs contain cementitious materials within the geosynthetic(s), which possess very different physical properties. Geosynthetics are typically buried and their performance is often assessed according to their tensile strength, whereas hardened cementitious materials are often exposed and their performance is typically assessed according to their compressive strength (or initial flexural strength for GCCMs/GCCBs). Initial flexural strength can be correlated with other key durability characteristics such as abrasion resistance, freeze thaw resistance and resistance to chemical attack.

As GCCMs and GCCBs are the only geosynthetics to contain cementitious material and are a relatively new class of geosynthetic, pre-existing geosynthetic Harmonised European Standards (hENs) used for CE marking of conventional geosynthetics do not include methods for understanding the performance of the cementitious material contained within a GCCM/GCCB. In addition, hENs do not cover the use of geosynthetics for surface erosion control applications and require the geosynthetic to be buried within one month of installation.

Figure 2: Slope protection surface erosion control using a GCCM

Figure 3: Channel lining surface erosion control using a GCCM

The cured cementitious material provides key performance properties for GCCMs/GCCBs in surface erosion control applications such as channel lining, slope protection, bund lining, concrete remediation and culvert lining. It is therefore important to test the properties of the cured cementitious material so that the behaviour of the GCCM/GCCB as a hardened composite can be understood, and provide a CE
mark with declared performance properties relevant for the intended use of Surface Erosion Control.

The Solution

The CPR sets rules for the marketing of construction products within the EEA. When a construction product is not covered by a hEN, a CE mark can be obtained through the European Technical Assessment (ETA) route. When marketed within the EEA and the United Kingdom, it is mandatory for all geosynthetics sold for a specific function/ intended use covered in a hEN or ETA to be CE marked to that relevant hEN or ETA.

In order to prepare an ETA, first of all a European Assessment Document (EAD) must be created. The EAD specifies the essential performance properties that must be tested for the construction product and provides essential information for Notified Bodies to assess in order to provide Factory Production Control (FPC) certification.

In 2015, the process of creating an EAD for GCCMs and GCCBs began, with the intended use of erosion control and containment applications including: channel lining, slope protection, bund lining, concrete remediation and culvert lining. This EAD 080009-00-0301 included key performance property testing of the cured cementitious material in the GCCM/ GCCB, such as initial flexural strength, abrasion resistance, freeze-thaw resistance and retained flexural strength after durability testing.

Once the EAD was approved (pending citation by the European Commission), construction product specific ETA’s could be prepared. The ETA reports the results of a construction product’s essential property testing as specified by the EAD and forms the basis of the declared values in the Declaration of Performance (DoP). The ETA for Concrete Canvas^® GCCMs and CC Hydro^™ GCCB was first published in 2019. The ETA for CCX^® GCCMs and GCCBs was published in 2022.

Note: ASTM D8030 ‘Standard Practice for Sample Preparation for GCCM’ details the procedure for the hydration and curing of GCCM material for subsequent physical property testing. GCCMs are hydrated in the field by spraying or immersion, but immersion almost always occurs due to pooling of water on GCCM surfaces. Immersion will produce the highest water/cement ratio possible in the GCCM, resulting in the lowest in-service compressive strength and (according to BR331 – Design of Normal Concrete Mixes: second edition) the poorest durability of the cementitious material. It is critical that the performance of a construction material is assessed based on the worst-case area, as a failure will usually occur at the weakest point in the structure. It is therefore necessary to understand the in-service performance of GCCMs that have been hydrated by full immersion. Test specimens cured in accordance with ASTM D8030 are cured by immersion in hydration tanks for 24 hours.

Recommendations

It is the duty of the manufacturer, the importer and the suppliers of geosynthetic products to ensure compliance and the CPR provides an enforcement and penalty regime to ensure that construction products placed on the market adhere to these standards.

It is important for the users of GCCMs and GCCBs to check which functions, applications and intended uses are covered under the hEN or EAD for which a product has been CE marked and marketed. For example, EAD 080009-00-0301 covers the use of GCCM and GCCBs in erosion control and containment applications such as the lining of water channels, slope protection, bund lining, concrete remediation and culvert lining. The traditional geosynthetic hENs typically cover buried uses for protection, filtration, reinforcement and separation. Therefore, GCCMs/GCCBs that are CE marked under these hENs are not suitable for surface erosion control applications and should not be used.

It is also important that users check that the product DoP includes data on key durability properties unless they are to be buried on the day of installation.

In January 2024, the Notified Body, ASQUAL, issued Concrete Canvas Ltd with its latest FPC certificate. Together with the ETAs for Concrete Canvas^® & CC Hydro^™ (ETA-20/0912) and CCX^®(ETA-22/0683), this continues to make Concrete Canvas Ltd products the first and only GCCMs and GCCBs to be CE marked for use in Surface Erosion Control applications.

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