Recycling composites

The use of lightweight components stands or falls by the choice of materials. Product value, product costs, production costs, development costs and risks are however difficult to estimate when talking about less well-known materials such as composites. Moreover, the wide range of materials and processes makes selection even more difficult.

This is why the SLC-Lab, and the department dealing with sustainability at Sirris, as well as their partners, want to pass on the essential tools and methodologies to help designers and OEMs make the right choices. In providing support we want to provide greater clarity with the publication of various white papers dealing with current issues. The first white paper introduces the issue of sustainability, the second white paper goes deeper into 'recycling composites'.


Thanks to their lower weights, composites typically lead to lower CO2 emissions. Despite increasing advances in sectors such as aerospace and the automotive industries, another sustainability aspect is putting the material to the test: two materials joined together form an inherently strong and tough entity that is difficult to separate again. This results in substantial consequences for the material complexity of waste flows on product disposal. Because of this complexity a closed recycling loop can only be achieved by deploying energy-intensive separation processes.

The following processing routes for recycling composites are normally suggested: mechanical milling, thermal processing (e.g. pyrolysis and processing in the cement industry) and solvolysis (the chemical route). Although these technologies can be applied to both carbon and glass composites, a shift has taken place in practice. Glass fibre composites are mostly processed using mechanical milling and end up in the cement industry, while carbon fibre composites are processed using either pyrolysis or solvolysis.

This white paper discusses recycling both types of materials individually:

  1. Recycling composites: hopeful developments for the Belgian circular economy (introduction)
  2. Recycling carbon fibre composites: high quality recyclate in answer to ambitious legislation
  3. Recycling glass fibre composites: what is the cheapest way of disposing of this enormous waste mountain?

(Source picture: Fiberline)