Chinese design studio Bentu Design explores the potential of industrial waste through material-driven products for architecture and public space. With its ‘X’ stool, the studio demonstrates how fly ash—an abundant by-product of coal combustion—can be transformed into a durable and circular material for outdoor furniture.

From Industrial Waste To Urban Resource

In Hukou County, where Poyang Lake meets the Yangtze River, the Shenhua Power Plant produces large volumes of fly ash every day. For every 100 tonnes of coal burned, between 15 and 45 tonnes of fly ash remain. For decades, industries disposed of this material in landfills or stored it in large deposits. This practice caused environmental risks, including soil degradation and water pollution.

Designers and material researchers now treat fly ash as a valuable secondary resource. The concept of “The Second Mine” reflects this shift. It refers to extracting value from existing waste streams instead of relying on virgin materials. This approach supports circular design and reduces environmental pressure.

Material Innovation In Concrete Design

Bentu Design developed the ‘X’ stool using a composite of fly ash and other industrial by-products. These include steel slag, recycled ceramics from Jingdezhen, red sandstone tailings, and silica powder. The final material contains more than 90% solid waste.

In traditional concrete, cement generates the highest carbon emissions. Bentu reduces the cement content by replacing part of it with fly ash. This change lowers the environmental impact and reduces production costs. At the same time, fly ash improves the material’s performance. Its fine particles create a denser structure and reduce permeability. Over time, chemical reactions within the material increase strength and durability. This results in better crack resistance and long-term
stability.

Designing With Circular Systems

The ‘X’ stool is designed for outdoor and public environments. Its weight and strength make it suitable for urban landscapes and architectural applications. The project shows how waste materials can meet high technical standards.

Bentu also highlights the aesthetic potential of recycled materials. By using locally sourced waste, the material reflects regional identity. This approach adds cultural value while supporting local production systems.

Towards A Second Life For Materials

The ‘X’ stool illustrates how designers can turn waste into a resource. Bentu Design combines material research with circular thinking to create new applications for industrial by-products. This strategy reduces emissions and opens up new opportunities for sustainable design.

Source & photos: Bentu Design