DISCOVER2: Development of innovative, sustainable materials for roofing systems

Conventional flat roof covering systems such as bitumen or synthetic polymer based membranes are of high quality and have a long service life, however, they are mainly made from petroleum resource. Since this fossil resource is finite and its extraction, refining and use contributes to climate change, there are ample reasons to consider more sustainable alternative materials while retaining the required technical and functional characteristics of roofing membranes.

Biobased roofing

The ultimate goal of the project was the development of an environmentally friendly alternative to the existing bituminous roofing systems, in which the fossil bitumen has been replaced by biobased raw materials. In the DISCOVER2 project a large range of biobased streams with characteristics to fulfil the requirements of a durable roofing system were evaluated. This was a continuation of the previous DISCOVER1 project which started in 2016. One important issue is that biomass derived streams are less hydrophobic and more reactive than bitumen, which is a bottom distillate of the fossil oil refinery. Therefore ample focus was given to side streams which are available in large quantities from the pulp & paper and agri & food industries with properties resembling the characteristics of fossil bitumen.

Results  on the evaluation of biobased components such as lignin

After various cycles of lab scale evaluations at both WFBR and BMI, binder mixes were designed based on fully biobased components comprising for example biobased lignin and vegetable oils. These binders showing high potential to finally develop a 100% biobased binder for bituminous roofing systems. At the end of the project these binders were manufactured at lab scale up to around 1 kg and evaluated for its main characteristics, such as mixing ability, homogeneity, visco-elastic and rheological behavior, penetration value and stability. The results found are close to the desired range of properties for sustainable roofing systems. Industrial applicability with current manufacturing principles seems possible with these innovative materials. Furthermore, LCA results indicate that the use of biobased streams can have a significant positive impact on the environment in terms of a lower carbon footprint, especially if the carbon sink function of biomass is taken into account. In that case a net negative total carbon footprint of more than 1 kg per kg biomass is feasible.

This project is a collaboration between Wageningen Food & Biobased Research, roofing producer BMI (formerly Icopal) and biomaterials producer Stora Enso.