NCC tests lignin for greener asphalt

NCC and RISE (Research Institutes of Sweden) have commenced collaboration to test the renewable raw material lignin as a binding agent in asphalt. The project is part of NCC’s efforts to reduce emissions of greenhouse gases and dependence on fossil products.

“By replacing fossil raw materials with renewables, we will reduce greenhouse gas emissions from road construction and maintenance, while also broadening the range of raw materials for our end product. In this project, we see potential to reduce carbon emissions by up to 20 percent for finished asphalt and we are now set to test and evaluate this,” says Robert Lundström, R&D manager NCC Industry.

The project uses lignin extracted from black liquor, a residual product from the pulp industry. Lignin is a domestic raw material that is available in large quantities, thereby facilitating a large-scale and cost-effective environmental initiative.

“The black liquor is processed, and the lignin is extracted at our demonstration facility in Bäckhammar, in Värmland. The facility collaborates with Nordic Paper. They send us the black liquor and then the filtrate is returned to them after processing. We ensure that NCC receives lignin of the right quality for mixing into the asphalt,” says Maria Ölmhult, project manager at RISE.

The project is expected to continue for more than six years and comprises full-scale trials using various types of mixing methods in various volumes in the asphalt. In 2021, the finished asphalt will be laid on five different stretches of road in Värmland to evaluate its durability and function.