Waste red mud and ore tailings transform carbon-fiber geopolymers

A recent study published in Case Studies in Construction Materials explores the use of red mud and ore tailings to enhance carbon-fiber-reinforced geopolymer composites for electromagnetic shielding. These composites, which incorporate industrial waste, offer a low-carbon alternative to traditional cementitious materials. The research, led by Lan-Ping Qian and Ti-Lin Fang, investigates the potential of these waste materials to replace fly ash in geopolymers, which are known for their reduced carbon emissions and dielectric properties.

Red mud and ore tailings, both rich in aluminosilicate and metal phases, were used to replace 20, 40, and 60 percent of fly ash in the composite matrix. The study found that while red mud reduced compressive strength due to its crystalline phases, ore tailings improved strength by acting as micro-aggregates. The addition of carbon fibers at a constant 0.5 percent by mass significantly enhanced the conductive network, reducing resistivity and improving electromagnetic shielding effectiveness.

Electromagnetic tests in the X-band range demonstrated that the waste-modified composites, particularly those with ore tailings, achieved superior shielding effectiveness. The first tailings replacement reached a peak shielding effectiveness of 32.2 decibels, while the second achieved 33.5 decibels. The study highlights the potential of these materials to serve as functional building components that address both electromagnetic pollution and industrial waste management.

Microstructural analysis confirmed the active role of waste materials in modifying the geopolymer matrix, with carbon fibers bridging microcracks and enhancing mechanical properties. The researchers emphasize the need for further exploration of different fiber contents and long-term durability to advance these composites from laboratory studies to practical applications in construction.