New technology turns iconic Japanese bento pots into building materials

A research team at the Saitama Institute of Technology has developed a new, low-energy technology to upcycle used ceramic train-bento containers into high-quality interior tiles. The innovation provides a circular solution for a famous local product while addressing resource scarcity and the high carbon footprint of conventional tile manufacturing.

The research is led by Professor Teruhisa Hongo, and focuses on the iconic pots from “Toge no Kamameshi,” a popular ekiben (station bento) sold at Yokokawa Station in Gunma Prefecture since 1958. The ceramic Mashiko-ware pot was originally adopted to meet customer demands for a hot meal during long train journeys.

Despite collection efforts, the annual recovery rate for the pots remains around 30 per cent, becoming a significant waste stream. At the same time, Japan faces a depletion of high-quality clay for tile production. Furthermore, the industry is challenged by the environmental impact of its energy-intensive manufacturing process, which requires firing temperatures between 900 and 1300°C.

The research team developed a method that bypasses the need for high heat. The process involves crushing the used ceramic pots and applying mechanical energy, a technique known as mechanochemical treatment, to alter their crystalline structure. An alkaline activator is then added to the powder, which hardens into a durable tile at just 60°C. The resulting tiles possess a sturdy bending strength, meeting the requirements for indoor use as specified by Japanese Industrial Standards (JIS A5209).

The team states that this environmentally friendly technology has wide applications. It can be adapted for various materials containing silica and alumina, including discarded pottery, firebricks, and roof tiles. The process can also be used to create other building materials such as bricks, blocks, and panels. Research continues to expand the new technology’s potential.