Wageningen University & Research and project partners BMI and Stora Enso have taken a major step towards a 100% biobased alternative for bitumen roofing. This has been achieved within DISCOVER 2, a follow-up to a previous project in the CBPM programme and partly financed by the Dutch government's Top Sector Chemistry initiative.
Bitumen is commonly used as a basis for roofing products due to the material's excellent functional properties. A major disadvantage is that bitumen is made from petroleum, like the polymers APP and SBS which are also processed in many roofing products. Another challenge is the varying quality of bitumen on the market, which can be partly attributed to the closure of a number of European bitumen plants such as those in Rotterdam and Antwerp.
Lignin as the basis
In DISCOVER 2 scientists from Wageningen Food & Biobased Research studied environmentally friendly alternatives to existing roofing based on bitumen. They tested a long list of possible options, all of which are available on a large scale as side streams from the pulp & paper industry and agrifood sector. The research showed how lignin is one of these alternative resources. This natural adhesive has proven itself as a suitable replacement for bitumen and is already being used in asphalt with good results.
Mixing bottleneck
While the main bottleneck to using lignin was mixing it with other necessary biobased components into a homogenous mass, the project eventually succeeded in doing so. "This was a crucial step," says Richard Gosselink, expertise leader at Wageningen Food & Biobased Research. "We used physical and chemical modification technology to make the components miscible." The resulting technological knowledge is also being used in an ongoing project titled '100% biobased bitumen for asphalt'. Gosselink: "Asphalt requires a different hardness than roofing, which means it needs a different composition of biobased components. This project has given us many useful insights into the mixing process."
Prototype before upscaling
Wageningen Food & Biobased Research is now seeking partners to help take the next step towards 100% biobased roofing products. The following phase will be to make a prototype which Wageningen scientist Ted Slaghek says should be available within three years: "There is enormous interest from the market. Roofing manufacturers are actively looking for eco-friendly alternatives to their existing products." Supported by Wageningen expertise, Slaghek says these companies can expect the technology for upscaling to be available in six to seven years, allowing a fully biobased alternative to be brought to the market soon after.
