Road construction in the interests of resource optimisation

Roads must be designed to withstand the impacts of traffic and climate for as long as possible. In addition to detailed planning, the most important factors influencing the quality – and thus the possible service life of a road – are the execution and selected construction materials. At the same time, ecological aspects such as resource and environmental protection must be taken into account. The challenge for municipalities, federal states and the federal government: to achieve the best result with limited resources.

Primary and secondary aggregates: A perfect combination

As a matter of principle, product-neutral tendering is stipulated in the relevant German procurement regulations. Fact is, that due to according environmental specifications, the possible use of secondary aggregates compared to primary materials is limited. Local environmental conditions, technical requirements and the type of execution are influencing factors that have to be assessed in the tendering phase for each project. Due to the time and effort involved, many tendering bodies tend not to formulate tenders in a product-neutral manner, so that only primary building materials are permitted, and thus, execution with secondary raw materials is excluded.

But: If the relevant local requirements are met, execution with substitute construction materials or secondary aggregates is just as safe as construction with primary building materials, and at the same time economically more interesting. Anyone who decides to use substitute building materials – often in combination with primary building materials – demonstrates commitment to reuse, resource conservation and climate protection, which also pays off in economic terms.

IBA aggregates amend the natural aggregate sources

Use in road construction and earthworks

granova® incinerator bottom ash is most frequently used as a substitute building material/secondary aggregate in road substructures as subgrade. Rarer and only permitted in selected road load classes, granova® is also used in the subbase, such as the frost blanket or lower base/base course in the road pavement structure.

Road construction with incinerator bottom ash aggregates in subgrade layer

Main application area of granova® IBA in Germany: Subgrade layer

Ecology and technological aspects

granova® IBA can be used as substitute aggregate in German road construction and earthworks subject to the following environmental conditions:

  • Project location outside water protection areas, flood plains and hydrogeologically sensitive areas
  • Minimum distance from the highest groundwater level to the formation 1 m
  • Minimum distance to buildings susceptible to corrosion of 0.5 m
  • Application under watertight layers such as asphalt or concrete
  • Private building projects require a permit under water law

The following table summarises the German application areas for granova® as a substitute material in road construction, taking into account ecological and constructional requirements:

Summary of application areas in road construction for incinerator bottom ash (IBA)

Summary of German application areas in road construction and earthworks

Realisation: IBA as core material

When granova® is used in the road subgrade, different construction methods can be used, whereby the core construction method is chosen most frequently. In North Rhine-Westphalia (NRW), for example, this is done in accordance with the NRW Federal Council Decree (Gem.RdErl. NRW) called "Requirements for quality monitoring and the use of incinerator bottom ash in road construction and earthworks". Similarly, there are requirements for other federal states based on LAGA Notice M20 or the M TS E leaflet on construction methods for technical safety measures for the use of soils and building materials with environmentally relevant constituents in earthworks.

An overview of construction methods can also be found in our German Handbook on secondary aggregates.

Use of incinerator bottom ash mainly in core construction method

Core construction method in accordance with Gem.RdErl. NRW: Embankment, cover with natural, cultivable soil

Incinerator bottom ash road construction: Core design according to M TS E regulation

Core construction method according to M TS E: Embankment with core of soil/aggregates with environmentally relevant constituents

Our service package

In addition to the delivery of our quality-controlled secondary aggregates, we offer a service package from project planning to completion:

Incinerator bottom ash delivery for road construction: Service package

Advantages at a glance

The construction with granova® is not only a sustainable option, but offers many other advantages:

  • High economic efficiency due to cost savings compared to conventional construction
  • Technologically high-quality construction material with according test certificates
  • Conformity with technical regulations for road construction and earthworks
  • Proven environmental compatibility
  • Execution in accordance with the Circular Economy Act
  • Conservation of primary raw materials
  • Reduced disposal fees through optimised recycling