Abstract :
[en] In Belgium, construction and demolition waste represent each year about 20% of the total waste. Since in the future, the amount of waste and the consumption of raw materials will only increase, their recycling is a real challenge for the construction sector.
Among its activities, Derbigum produces bituminous membranes for roof waterproofing applications. In a sustainable and ecological perspective, Derbigum has developed a unique recycling process for roofing clippings and roofing waste, coming from the production, the installation or the deconstruction of buildings. For the latter, Derbigum ensures the required level of quality through the establishment of trustworthy relationships with various targeted collectors/reclaimers. Roofers can deposit free of charge their roofing clippings at selected dealers of building materials and roofing specialists. Doing this, they can economize 15% on the dumping costs. At the end of the recycling process, part of the material thus obtained is incorporated into the formulation of the membranes, making it possible to reduce the use of primary resources (Figure 1).
Figure 1: Circular process for bituminous membranes at Derbigum
In order to objectify the environmental gain associated with the incorporation of recycled material into membranes, Derbigum has wish to carry out a Life Cycle Assessment (LCA) of its recycling unit.
The study is made in the cut-off perspective, and the border of the system stops at the factory gate. The functional unit is 1 kg of secondary raw material that can directly be included in the production process, called Gumix (for gum mix).
All the data for the recycling process are primary data transmitted by Derbigum.
The evaluation is done with CML-IA method (http://cml.leiden.edu/software/data-cmlia.html), in Simapro software (PRé-Consultants BV, NL), with Ecoinvent 3.4 (Wermet et al., 2016) database for the generic data.
The results show that the collection and recycling of waste from their bituminous membranes by Derbigum in order to produce reusable components to replace bitumen in their formulations allows environmental benefits in all the impact categories considered (CML-IA method, toxicity categories not included). The energy requirements for waste treatment are largely offset by the saving of raw materials and their transport to the Perwez production site.
CO2 emission are five times lower for the production of 1 kg of Gumix than for 1 kg of bitumen. Fossil fuel consumption is more than twenty times lower. The substitution of 25% of virgin bitumen by the same amount of Gumix in a binder formulation leads to a decrease of 13% of the impacts in the Global warming potential category.
The life cycle assessment of the Derbigum recycling unit has highlighted not only the environmental benefits of the recycling process, but also revealed some "hot spots" in the process that can be optimized or improved.
Acknowledgement
The authors want to acknoledge Imperbel-Derbigum company and the Walloon Region.
References
Wernet, G., Bauer, C., Steubing, B., Reinhard, J., Moreno-Ruiz, E., and Weidema, B., 2016. The ecoinvent database version 3 (part I): overview and methodology. The International Journal of Life Cycle Assessment, [online] 21(9), pp.1218–1230. Available at: <http://link.springer.com/10.1007/s11367-016-1087-8> [Accessed March 2017]
