Solving the smell problem: researchers unlock wider use of low‑carbon road binder

A targeted research collaboration between the University of Auckland and Road Science has removed a critical operational barrier to the wider use of BioBind, a low‑carbon bitumen replacement for road construction - by solving an issue you could quite literally smell.

Facilitated by UniServices, the collaboration focused on a specific and practical challenge encountered during production of BioBind: a strong and polarising odour generated during production. While the product itself was already technically proven, the odour raised concerns around community acceptance, and long‑term wider adoption.

Road Science had already designed and manufactured BioBind prior to the research project, so the University of Auckland’s role was clearly defined: to identify the source of the odour observed during production and to develop practical strategies to materially reduce it.

This targeted scope ensured progress enabled a fast pathway from research to implementation. Within a short timeframe, university researchers moved from problem identification to a validated, scalable mitigation solution. 

"The odour produced by BioBind was identified as concern for wider adoption of the product," says Professor Saeid Baroutian, who led the University’s chemical engineering research team.

"If new materials are to succeed in the real world, they must not only perform technically - they must also be practical and acceptable to the environments they are used in."

BioBind is engineered with renewable resources with the primary component coming from trees. It is a by‑product of pine forestry processing, meaning it is derived from forestry waste rather than crude oil, and its cutting-edge formulation boasts significantly lower embodied carbon than that of traditional bitumen.

However, the inclusion of this renewable material also alters the emissions profile during heating and processing, releasing a different mix of odorous compounds.

Understanding which of those compounds were responsible for the problematic smell - and how to reduce them - became the central focus of the research. 

In Phase One of the project, the University team - led by Professor Baroutian, with Dr Mercedeh Lazarjani as postdoctoral researcher - conducted detailed chemical analyses to identify the specific contributors to the odour.

In Phase Two, the researchers developed and tested a combined mitigation strategy designed to target those specific odour‑causing compounds. The approach resulted in a substantial reduction across nearly all major odourants associated with BioBind manufacture.

Importantly, the solution was not intended to reduce all volatile organic compounds indiscriminately. Instead, it was explicitly designed to address the odour‑related compounds that were identified as a potential product adoption concern.

This brought BioBind’s odour profile much closer to that of conventional bitumen, while preserving its existing performance characteristics and lower‑carbon benefits. 

Crucially, the mitigation strategy is highly scalable. It is applied during BioBind production and does not require changes to downstream activities such as transport, asphalt mixing, or paving.

"This was about finding something practical," says Professor Baroutian.

"The solution integrates into existing production processes without new equipment, major capital investment, or additional labour. That’s what makes it viable in an operational environment."

By addressing the odour issue, the research removes any concerns for adoption of this low‑carbon binder in road construction.

Darcy Rogers, Head of Strategy, Growth and Innovation at Road Science says the project demonstrates the value of targeted, solution-focused research partnerships:

"Working alongside the University of Auckland allowed us to tackle a challenge that required specialist expertise and access to extended resources. This collaboration shows how targeted research can deliver practical, scalable solutions that industry can implement quickly."

Professor Baroutian agrees: "This is what effective collaboration looks like - identifying a real barrier, staying focused on the problem, and delivering a solution that works in practice."

This project builds on earlier and parallel work between Downer (of which Road Science is a division of) and the University of Auckland exploring next‑generation road technologies, materials, and systems.

Initiatives such as the Inductive Power Transfer (IPT) Roadway Project and the development of the Accelerated Pavement Test (APT) 'rocker' facility at Road Science’s Auckland asphalt plant for pavement-based wireless EV charging trials reinforce how long‑term industry–academic relationships can respond rapidly when specific challenges arise.