SAMI low‑carbon asphalt in Auckland: performance and design notes for road engineers
Reviewed by Joe Ashwell

First reported on Roads & Infrastructure (AU)
30 Second Briefing
SAMI Bitumen Technologies’ SAMIGreen polymer modified binder has been used to produce a low‑carbon asphalt mix on the first Auckland Transport‑approved project to incorporate such an additive. The binder replaces part of the conventional bitumen with a sustainable polymer formulation, cutting embodied carbon in the surfacing layer while maintaining performance requirements for rutting, fatigue and texture depth. COLAS New Zealand and SAMI say the approval process and field performance data could form a template for wider adoption of low‑carbon binders across New Zealand’s state highway and local road networks.
Technical Brief
- SAMIGreen is supplied as a polymer modified binder compatible with standard asphalt plants and spray equipment.
- SAMIGreen’s formulation is designed to be drop‑in for dense‑graded and stone‑mastic asphalt mixes.
Our Take
SAMI Bitumen Technologies’ work with Auckland Transport in New Zealand sits alongside its new Australian technical centre (26 Feb 2026), signalling that SAMI is using both markets as testbeds for advanced binders and additives rather than treating them as separate regions.
With COLAS rolling out the ‘One COLAS Bitumen’ framework globally (30 Nov 2025), any SAMI-branded sustainability initiative in Auckland is likely to become a reference case for standardised low-impact products across COLAS’ wider network, not just a local trial.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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