THERMAL BEHAVIOUR OF INORGANIC POLYMERS SYNTHESISED FROM Fe-RICH SLAGS

Fe-rich slags are by-products of the non-ferrous, e.g. Cu and Pb, metallurgy. They can be utilised as precursors in the synthesis of inorganic polymers (IPs). IPs are used as a binder similarly to Portland cement (OPC) in construction materials. Depending on the mix-design, they have a lower CO2 impact compared to OPC and material loops are closed by using industrial by-products. Due to the difference in chemistry and reaction products between IPs and OPC new attractive properties arise. IPs are praised for their excellent fire-resistant properties. They are incombustible and upon heating their strength degradation is much lower than OPC due to the nature of their reaction products.
The thermal behaviour of Fe-rich inorganic polymers has not been fully explored. In this work IPs are produced by mixing the slag with KOH and/or K-silicates and their thermal behaviour is investigated. The compressive strength after firing, mineralogy and density are monitored as a function of temperature up to 1300 °C. Formation of new phases was observed above 700 °C. After firing to elevated temperatures a strength increase was observed. This increase goes hand in hand with a densification of the material. The first results indicate that Fe-rich IP shows promise to be used as a binder in fire-resistant concretes or as the matrix in fibre-reinforced composites.