What is circular concrete?

Aggregate and filler without a binder function

European standard EN 12620 contains the relevant properties of aggregates and fillers used in concrete. If the requirements of the standard NBN EN 12620 'Granulates for concrete' are met, recycled granulates are generally suitable for use in concrete. However, the fact that the granulates are generally suitable does not mean that they can be used without question, as there may be some specific requirements depending on the application.

There are also standards for concrete itself, such as the European standard NBN EN 206, which specifies how concrete should be prescribed and produced and what properties the concrete should have. The European standard is complemented by Belgian standard NBN B 15-001, which contains a number of explicit provisions on the use of recycled granulates. Together, these documents provide a sound basis for assessing the fitness for use of recycled granulates.

Filler with a binder function

European standards EN 450-1 (pulverised coal fly ash), EN 15167-1 (ground granulated blast furnace slag) and EN 13263-1 (silica fume) define the relevant properties for fillers with a binder function for use in concrete.

In addition, there are three options for assessing the binder contribution of the filler:

  • the k-value concept with a generic value for the relevant alternative filler per cement type
  • the concept of equivalent performance for a combination of one or more specific cements with one or more specific fillers
  • the concept of equivalent performance of defined combinations of cement and filler(s) with a composition similar to a cement according to EN 197-1.

These concepts are described in detail in CEN/TR 16639.


The European standards EN 197-1, EN 197-4 and EN 14216 describe the relevant properties of clinker-based cements. Combined with the properties of the alternative raw material, these documents provide a good basis for establishing an assessment basis for the suitability of the alternative binders for use in concrete.

In the Netherlands, there is also the CUR Recommendation 48 for assessing the suitability of new types of cement. It is assumed here that these cements have a similar influence on the structural properties of concrete within certain margins, which has no consequences for the structural calculation rules for concrete in accordance with NEN-EN 1992-1-1 (Eurocode 2).

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