Updated: 8 August 2024
Concrete products are made from a combination of cement, water and aggregate material.
The most common aggregates used in concrete are gravel, sand and crushed rock. Their presence within a concrete mix is necessary for the concrete to achieve its required strength properties.
Aggregates are sourced from local stone suppliers, who mine the raw stone material from quarries. As concrete production surges, so too does the demand for aggregate material, leading to the depletion of finite natural resources.
An alternative solution
What other materials can be used as substitutes for natural stone aggregates?
One answer is somewhat unexpected, but works: recycled plastic waste.
While searching for innovative materials with better environmental outcomes, SVC engaged with a company called Replas, who had successfully produced a recycled product that provided a sustainable, environmentally friendly replacement for mineral aggregates.
The product is made using post-consumer grade, ‘scrunchable’ soft plastic waste, collected from organisations such as Coles and Woolworths. It provides a solution for the safe disposal of harmful soft plastics, while simultaneously reducing the construction industry’s consumption of natural stone resources.
Compared to traditional stone aggregates, the recycled plastic aggregate is lighter, more thermally efficient, and easier to transport. Made from everyday waste items such as cling wrap, plastic bags and food wrappers, the final form of the aggregate material assumes a twisted, rock-like shape which bonds extremely well to concrete.
Effective disposal of soft plastic waste
While the REDcycle recycling program was in operation, 4 million pieces of soft plastic waste were collected in Australia every single day. Due to the levels of contamination present, this type of plastic waste is incredibly difficult to recycle, and the majority of it would often end up buried in landfill or dumped into the ocean, risking harmful toxins leaching into the environment as the plastic degraded over time.
The conversion of plastic waste into recycled plastic aggregate offers a promising solution.
When recycled plastics are used within concrete, they are locked away from the natural environment, tightly bound in a concrete enclosure without the ability degrade. Later, when the concrete product reaches the end of its lifespan and is crushed for recycling purposes, the recycled plastic aggregates can be extracted from the concrete for reuse.
Recycled plastics in precast concrete
SVC is an early adopter of recycled plastic aggregates, and is fully supportive of the material’s uptake within the manufacturing and construction industries. To incorporate this innovative aggregate material into our own manufacturing processes, SVC has invested in operational upgrades and internal product trials to ensure successful integration. The company is now deploying recycled plastic aggregates on a regular basis, while also reducing its consumption of virgin stone aggregates.
Hundreds of concrete products across SVC’s broad range of Civil product solutions now contain a percentage of recycled plastic waste. These products are distributed across Victoria for use in council works, major projects and infrastructure programs, allowing these projects to get closer to sustainability targets via material procurement.
Based on SVC’s current consumption of recycled plastic waste material, the numbers are impressive. Allowing a conservative estimate of 1.5 tonnes of plastic aggregates used per week at SVC, this translates to 72 tonnes of plastic aggregates per year, or a diversion of 18 million pieces of soft plastic waste away from landfill.
