For all products included in harmonized standards, the Declaration of Performance and the CE marking must be issued. The European standard UNE14889-1 establishes the definition, specification and conformity criteria for steel fibers.
The CE marking contains essential information about the product and includes references to other documents that also contain relevant information. This will be placed on construction products for which the manufacturer, importer or distributor has issued a Declaration of Performance. The affixing of the CE marking implies that the manufacturer, or where appropriate the distributor or the importer, assumes responsibility for the conformity of that product with the benefits included in the Declaration.
The CE marking together with the Declaration of Performance, help users of the fibers to check the performance of the product and to compare it with others that have the same technical characteristics.
The manufacturer is responsible for evaluating the performance of the product and for implementing factory production control, either through its internal quality control procedures or in collaboration with external laboratories. The results of the evaluation and the factory production control allow you to verify if the performance remains unchanged over time. The legal term to describe this process is “evaluation and verification of constancy of performance” (EVCP), in the directive on construction products, the term used is EoC (Conformity Assessment) and the external verifiers are the notified bodies. Subsequently, the company issues the Declaration of Benefits (DoP).
The following flow diagram shows the different stages to be fulfilled by each of the parts.
The evaluation of the products is carried out by defining the value of a series of characteristics that are called essential characteristics. Both Annex ZA of the harmonized standards and the European Assessment Documents (DEE) define these essential characteristics. These may be different for the different intended uses of the product: if a product has more than one intended use, the characteristics for each will be described. The list also includes the EVCP system for each of the essential characteristics.
Assessment and verification systems of constancy of performance (EVCP systems)
Once the list of essential characteristics corresponding to a product has been obtained, it is necessary to check the procedures to be followed to declare the performance of each of the essential characteristics, such as test methods or tabulated values, for example. These procedures are mandatory in sample testing. Likewise, it will have to be explained in detail what the factory production control will be.
In some cases, the EVCP that is applied to each essential characteristic will require the intervention of a notified body to carry out some tasks. The following table shows the tasks that correspond to the manufacturer and the notified bodies, respectively, depending on the EVCP that is applied. Simply indicate the number of the EVCP system that has been used for the evaluation of the product, which must be one or more of those established in the harmonized technical specification itself; usually in harmonized standards, i.e. 1+ or 1 or 2+ or 3 or 4.
If all the characteristics of the product fit into system 4, the intervention of a notified body is not necessary. If they fall within system 3, the product must be tested by a notified body (in this case a laboratory), which may be different for each essential characteristic. If they correspond to systems 1, 1+ or 2+, the notified body collaborates with the manufacturer during the evaluation and performs some tasks in the factory, so it is usually best to hire a single notified body to perform all the tasks.
According to the European standard UNE14889-1, in the case of steel fibers, two conformity verification systems are mainly defined:
Conformity verification system 1: for structural use in concretes, mortars and pastes. When the addition of the fiber is intended to contribute to the bearing capacity of the concrete.
Conformity verification system 3: for other uses in concretes, mortars and pastes.
In the event that the steel fibers are used for structural use (system 1), a series of tasks are assigned under the responsibility of the manufacturer and others under the responsibility of the product certification body (notified body); Among them is the fiber concrete strength test.
The steel fibers are classified in System 1, intervention of a notified body declaring the effects on the Strength of the concrete.
The resistance of the concrete to flexotraction, for the purposes of the EHE Instruction, refers to the resistance of the unit of product or kneaded and is obtained from the results of the test of rupture to flexotraction, in a number equal to or greater than three; These must be carried out on prismatic specimens of width equal to 150 mm, height equal to 150 mm and length equal to 600 mm, 28 days old, manufactured, preserved and tested in accordance with UNE-EN 14651.
The criteria set forth in the Instruction to obtain the value of the tensile strength fct, based on the results of the indirect tensile test, are valid as long as they refer to the limit of proportionality.
From the test proposed in UNE-EN 14651 the crack load-opening diagram of the concrete is obtained (figure A.14.1). From the load values corresponding to the proportional limit (FL) and to the crack openings 0.5 mm and 2.5 mm (F1 and F3 respectively), the value of flexural tensile strength (fct, fl) and the corresponding residual flexural strength values: fR, 1 and fR, 3
The calculation of the flexural strength and residual flexural strength values according to the mentioned UNE-EN 14651 standard is carried out assuming an elastic-linear distribution of stresses in the section of rupture.
All rimsa references of steel fibers and structural polymers have CE marking; the same, is guaranteeing that the benefits of the product are those that have been declared. Here we show an example of the Declaration of Performance of our hook 50/1 (50mm long and 1mm diameter), evaluated and verified the consistency of product performance under system 1.