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Sustainable materials: is there a concrete solution?
- Global extreme weather events are intensifying due to the climate crisis; New York City's subway system shut down following 200+ millimetres of rainfall, the highest recorded since 2015.
- The construction industry contributes 11% of global carbon emissions, driven largely by impermeable infrastructure that exacerbates flooding.
- China poured more concrete in two years than the USA did in the entire last century, a trend associated with massive carbon emissions.
- Cement production alone accounts for 8% of global man-made CO2 emissions (5 billion tonnes annually), making it the third-largest source of greenhouse gases after coal, oil, and gas.
- Finnish company Bettila is developing a cement-free concrete alternative using industrial waste (e.g., from steel production) and AI to generate recipes that reduce raw material CO2 emissions by up to 80%.
- Scalability concerns exist for Bettila's solution, as the volume of industrial waste is relatively small compared to the total volume of global concrete production.
- Hemp-based materials, specifically "chiv" mixed with lime, are being used to create fireproof, high-thermal-inertia insulation that can reduce a 300-square-meter house's construction emissions from 150–200 tons of CO2 to zero.
- Hempcrete is not suitable for major infrastructure due to insufficient mechanical strength and durability compared to concrete, though it is viable for extensions or standalone homes.
- Cambridge University's Michael Ramage's team demonstrated the viability of Cross-Laminated Timber (CLT) with a theoretical 300-meter tower, using engineered wood layers glued at 90-degree angles to replace steel and concrete.
- CLT construction is faster and quieter than traditional methods because components are prefabricated in controlled factory environments and assembled on-site like "flat-pack furniture."
- While CLT is combustible, fire safety is managed through strategies such as cladding wood in plasterboard, though designing for exposed wood while maintaining fire safety remains a technical challenge.
- Urbanization is accelerating, with 55% of the global population living in cities in 2018, a figure projected to rise to 68% by 2050, increasing demand for housing and infrastructure.
- Market demand for low-carbon buildings is driving the green agenda, with experts noting that consumer pressure is currently the primary force pushing designers and architects toward sustainable material usage.
- Homeowners often face a conflict between environmental values and financial constraints; for those with limited funds, the higher costs of sustainable materials can create a barrier to adoption despite the moral imperative.