Hoe ki angitū round one – WSP New Zealand Limited: lignin replacement for bitumen

WSP New Zealand Limited received funding of $145,000 (excluding GST) to carry out laboratory research on a range of lignin materials as bitumen replacements.

This project was in response to one of Hoe ki angitū, the NZTA Innovation Fund’s round one challenges – Accelerating the use of recycled materials and sustainable practices.

There are currently no sustainable, readily available options to replace bitumen in New Zealand.  The purpose of this project was to investigate the feasibility of developing lignin as a bitumen substitute

The project involved selecting and sourcing three different lignins, blending them with bitumen and carrying out a range of standard tests (“hardness” and “softness”) and comparing the results to New Zealand bitumen specification requirements. The expected environmental and economic impacts were then reviewed.

The key findings of this project showed that there were significant differences between lignins, and blending conditions need to be further evaluated to enable scale up to production volumes. The lignin blends had the effect of increasing the bitumen’s resistance to deformation at all temperatures, increasing the viscosity and the softening point, and increasing the stiffness, potentially making them more susceptible to cracking at low temperatures. This work has significantly advanced the understanding of the processes involved to ultimately develop a binder with 100% replacement of bitumen with lignin.

The next steps are to carry out further laboratory and performance testing, including how to modify the lignin to increase the proportion in which it can be mixed with bitumen, and carry out field trials of the best-performing blends.

Note – due to commercial sensitivities only the executive summary is available for this project. WSP can be contacted directly to discuss further details of this project. 

View the executive summary here: