Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Valorising South African lignin as a sustainable bitumen additive in pavement engineering
Thesis (MEng)--Stellenbosch University, 2026.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Stellenbosch : Stellenbosch University
2026
|
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613913399427072 |
|---|---|
| access_status_str | Open Access |
| author | Vermeulen, Ryan |
| author2 | Gorgens, Johann Ferdinand |
| author_browse | Gorgens, Johann Ferdinand Vermeulen, Ryan |
| author_facet | Gorgens, Johann Ferdinand Vermeulen, Ryan |
| author_sort | Vermeulen, Ryan |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2026. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/135620 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:43:41.995Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/135620 Valorising South African lignin as a sustainable bitumen additive in pavement engineering Vermeulen, Ryan Gorgens, Johann Ferdinand Tyhoda, Luvuyo Goosen, Elaine Simone Stellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Thesis (MEng)--Stellenbosch University, 2026. Vermeulen, R. 2026.Valorising South African lignin as a sustainable bitumen additive in pavement engineering. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/6d79a1a7-7bbd-4774-b53a-3b9b5fe3b780 The construction industry is one of the largest contributors to global carbon emissions; therefore, the demand for sustainable alternatives is constantly increasing. There is a large focus on finding material alternatives that fit within the context of a circular economy. One such material is lignin. Lignin is a biopolymer found in the cell walls of plants. Lignin-rich spent pulping liquors are produced as waste streams from the paper and pulp industry. Lignin is not widely utilised in higher value applications; however, literature has shown promise with regard to using lignin as a partial substitute for bitumen due to chemical similarities. Bitumen is a viscoelastic liquid obtained from the distillation of crude oil and is typically used to bind aggregates to produce asphalt. This study investigated the performance of four different lignin types (Sappi kraft, Mondi kraft, Sappi soda and Sappi lignosulfonate) sourced from various pulp and paper mills around South Africa. The kraft and soda lignins were separated from their respective spent liquors using acid precipitation, while the lignosulfonate spent liquor was spray dried. The lignins were characterised, and they were then blended with bitumen at a 10 wt% blending ratio. This study found that Sappi soda lignin increased the resistance to permanent deformation (69 %) and the elastic recovery percentage (586 %). This can be explained through the lower content of phenolic hydroxyl groups and lower S/G ratio in Sappi soda lignin, limiting the hydrogen bonding capacity. This increases the elasticity of the soda lignin-modified bitumen (LMB) blend, while the other types of lignins form a stiffening network in the blends. Soda LMB also showed a significantly higher critical high temperature (2 °C), as well as wet indirect tensile strengths (ITS) of the associated asphalt specimens (19.7 %). Both types of kraft lignins also generally improved the performance of the bitumen, while the lignosulfonates generally did not statistically significantly change the performance of the binder. This study thus concluded that all types of lignin tested are feasible as bitumen modifiers at a 10 wt% blending ratio, with the Sappi soda LMB blend performing the best. The soda lignin was then blended with bitumen at higher blending ratios (20 wt% and 30 wt%). The 30 wt% blends experienced phase separation, limiting the practical feasibility of this blend. The 20 wt% blend significantly improved the dry ITS of asphalt specimens made from the bitumen (26.7 %); however, the drawbacks of poor storage stability hinder the feasibility of this blend. This study thus concluded that Sappi soda lignin is feasible as a partial bitumen substitute up to a 10 wt% blending ratio. This thesis concluded that all types of lignins tested are suitable as bitumen modifiers at a 10 wt% blending ratio. Further studies should investigate the industrial feasibility of this process through techno-economic analyses and life cycle assessments. Further work is also required regarding the processing of the spent pulping liquor (spray drying versus acid precipitation) to understand how this effects the properties of the LMB. Masters 2026-04-02T10:19:26Z 2026-04-02T10:19:26Z 2026-03 Thesis https://scholar.sun.ac.za/handle/10019.1/135620 en Stellenbosch University 159 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Vermeulen, Ryan Valorising South African lignin as a sustainable bitumen additive in pavement engineering |
| title | Valorising South African lignin as a sustainable bitumen additive in pavement engineering |
| title_full | Valorising South African lignin as a sustainable bitumen additive in pavement engineering |
| title_fullStr | Valorising South African lignin as a sustainable bitumen additive in pavement engineering |
| title_full_unstemmed | Valorising South African lignin as a sustainable bitumen additive in pavement engineering |
| title_short | Valorising South African lignin as a sustainable bitumen additive in pavement engineering |
| title_sort | valorising south african lignin as a sustainable bitumen additive in pavement engineering |
| url | https://scholar.sun.ac.za/handle/10019.1/135620 |
| work_keys_str_mv | AT vermeulenryan valorisingsouthafricanligninasasustainablebitumenadditiveinpavementengineering |