What does ABC's circular supply model involve?

• A. Using shredded plastics from e-waste to replace some limestone and clay aggregates.
• B. Replacing all aggregates with plastics.
• C. Using shredded plastics to replace cement entirely.
• D. Discarding plastics after use.

Answer: (C)

In a circular supply model, the goal is to keep materials in use and minimize waste by feeding waste streams back into production. It emphasizes substituting virgin inputs with recycled or repurposed materials to close the loop and reduce environmental impact.

Using shredded plastics to replace cement entirely fits this idea most directly. Cement production is energy-intensive and a major source of emissions, so turning plastic waste into a replacement for cement would eliminate the need for new cement and keep plastics out of landfills, illustrating a true closed-loop approach. Of course, making this work in practice would require significant advances in materials science and performance, but conceptually it shows the circular aim of converting waste into a functional input and reducing reliance on conventional, high-impact materials.

The other options don’t align with the circular approach as strongly. Replacing only some aggregates with plastics still leaves virgin inputs and waste streams in use elsewhere, substituting narrowly rather than closing the loop. Replacing all aggregates with plastics is often impractical and may compromise material properties. Discarding plastics after use directly contradicts the idea of keeping materials circulating in the economy.