Red mud and ore tailings used in carbon fiber geopolymer for electromagnetic properties

Researchers have developed carbon fiber-reinforced geopolymer composites that achieve electromagnetic shielding effectiveness of up to 33.5 decibels in the X-band frequency range. This study, originally reported by Bioengineer.org and highlighted by the Advanced Carbon Council, explores the use of red mud and ore tailings to enhance these composites, offering 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, rich in aluminosilicate and metal phases, were used to replace 20%, 40%, and 60% of fly ash in the composite matrix. The study found that red mud reduced compressive strength due to its crystalline phases, whereas ore tailings improved strength by acting as micro-aggregates. The addition of carbon fibers at a constant 0.5% by mass significantly enhanced the conductive network, reducing resistivity and improving electromagnetic shielding effectiveness.

Geopolymers are man-made materials that function similarly to resins but are derived from minerals rather than petroleum. They are created from powdered materials rich in silica and alumina, mixed with an alkaline liquid to form a hard, stone-like solid. Industrial byproducts such as fly ash, slag, rice husk ash, or metakaolin are common starting materials. Geopolymers are gaining attention for their potential to significantly reduce the carbon emissions associated with cement production. In composites, geopolymers can replace the matrix that binds reinforcing fibers like carbon or glass.

Electromagnetic tests in the X-band range showed that the waste-modified composites, particularly those with ore tailings, achieved optimal shielding effectiveness. The first tailings replacement reached a peak shielding effectiveness of 32.2 decibels, while the second achieved 33.5 decibels. These materials have the potential to serve as functional building components that address 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. 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.