From soft plastics waste to structural building panels

Australian composites manufacturer Sustainable Infrastructure Systems (SIS) has revealed innovative structural building panels made from glass fibre-reinforced polymer (GFRP) and discarded soft plastics.

The lightweight, high-strength composite panels are the first in the world to be manufactured using post-consumer mixed soft plastics, which are blended with a proprietary material matrix, according to an announcement.

The prefabricated panels can have a structural strength on par with concrete, provide an up to 48 per cent reduction in embodied carbon compared to a concrete panel, and can last well beyond 100 years.

The technology represents four years of research and development in partnership with The University of Adelaide on a soft plastics recycling optimisation project at SIS’ Wingfield factory, in Adelaide’s north-western suburbs.

A significant portion of soft plastics used in the panels have been sourced from waste stockpiled following the collapse of Australia’s REDcycle soft plastics scheme.

SIS managing director Nick Wotton said: “There are potentially limitless applications for our panels in transforming everyday rubbish into structures with huge benefits for our clients, communities and the environment.

“Recycled plastics have been used in the manufacture of structural building materials for decades, but SIS’ technology is the first to incorporate unprocessed mixed post-consumer soft plastics into high-performance structural panels.

“Our structural panels provide clients with a genuine reduction in embodied carbon and will be increasingly attractive as more infrastructure contracts are requiring companies to demonstrate how they will reduce embodied carbon across projects.”

The first project to feature a prefabricated structural panel incorporating unprocessed soft plastics is a pedestrian bridge installed at Newenham, Mount Barker in partnership with Mount Barker District Council and developer Burke Urban.

The 7.5m x 3.4m bridge contains 70 per cent soft plastics, or the equivalent of 29 standard 240L kerbside recycling bins of items including shopping bags, plastic film and food wrappers.

The research team, led by GFRP specialist and Professor of Structural Engineering Scott Smith, focused on reducing the reliance on virgin materials.

SIS self-funded the development of the panels and aims to ramp up production of the GFRP composite panels in FY24 and FY25, creating an additional 15-18 full-time positions.

In addition to using post-consumer soft plastics, the company will this year also begin trials of manufacturing structural panels using wind turbine blades.

In 2021, SIS invested $2.4 million to manufacture GFRP structures under licence from Dutch company, InfraCore.

Picture: Sustainable Infrastructure Systems Managing Director Nick Wotton holding SIS’ proprietary soft plastic blocks used to manufacture the company’s world-first soft plastic structural panels.