Higgins Contractors Limited received funding of $88,400 (excluding GST) to carry out laboratory research on non-petroleum biogenic-sourced 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.
The objective of the project was to evaluate a range of different biogenic bitumen replacements.
Testing and research considered both the technical merits of alternative materials and other attributes such as whether they were sourced from New Zealand, were low-carbon, provide an economic opportunity for New Zealand’s forestry or horticulture industries, and would reduce New Zealand’s reliance on imported products and exposure to global supply chains.
The project involved blending vegetable oil, tall oil pitch and lignin into bitumen and assessing the engineering performance of the blends. The commercial and environmental sustainability of the various biogenic bitumen replacements was also assessed.
The key findings of the project were that bitumen blended with vegetable oil or tall oil pitch met the relevant technical requirements and their in-service performance is expected to be indistinguishable from conventional bitumen.
Challenges with bitumen compatibility and nuisance odour emissions arose when blending lignin with bitumen. Lignin is produced in abundant quantities in New Zealand, however none is currently available for use in roading applications. It is all consumed as biomass fuel in pulp mills. Tall oil pitch is produced domestically in small quantities, with much of it also being used as fuel in its own production. Use of vegetable oil as a biogenic component would bring the bitumen supply chain into competition with the food industry, as they compete for similar supplies. The food industry may pay a higher price than is likely to be economic for the roading sector. Widespread adoption of biogenic bitumen that is based on vegetable oil, tall oil pitch or lignin will most likely require importation of the feedstock as there is insufficient domestic production to meet the significant demands of the roading industry.
Next steps are to carry out real-world trials of vegetable oil and tall oil pitch to give confidence that the performance of the materials is satisfactory. Further investigation is required to understand how to blend lignin with bitumen before widespread use of this material can be recommended.
View the full report here:
| Bearsley, S., L. Crone, O. Gallagher, I. Waite, (2024). Biogenic Bitumen [PDF, 924 KB], Project Report RD6000522.1, Higgins Contractors Ltd, Palmerston North |
