Proceedings of 4th International Conference on Engineering for Waste and Biomass Valorisation vol:1 issue:1 edition:1 pages:935-940
4th International Conference on Engineering for Waste and Biomass Valorisation edition:4 location:Porto, Portugal date:10-13 September 2012
Continuous casting (CtCs) slag, produced at the final stage of stainless steel production, is the residue left in the continuous casting pot after the casting of ingots. It has little valorization potential because of its dusty appearance and therefore is currently land filled. Elemental analysis by X-ray fluorescence (XRF) shows high amount of CaO in the slag indicating that the slag may have cementing/binding capabilities. Quantitative phase analysis by X-ray diffraction (QXRD) shows that gamma dicalcium silicate is the major mineral phase in the slag with other minerals like cuspidine, priclase and bredigite are present in smaller amounts. The slag mortar (slag with 0-5 sand in 1:3 ratio) can be activated using potassium hydroxide (KOH) in combination with potassium silicate (in 25%, 50% and 75% replacement of alkali) as activator when steam cured at 80°C. Isothermal conduction calorimetry at 80°C showed elevated heat evolutions at higher replacements of silicates in the activator solution. Steam cured slag mortar samples were found to achieve strengths above 15 MPa at 28 days. SEM images show minor presence of K in hydrated slag although showing definitive presence of Mg at some places. The results show the potential of CtCs slag to be used as a binder component contributing to valorisation of recycled material into construction material.