Hydration and carbonation curing of high ferrite clinker (FePC) synthesized using EAF slag

Abstract

This study explores the use of Electric Arc Furnace (EAF) slag as a sustainable alternative raw material in cement clinker production. The research demonstrates the synthesis of ferrite-rich clinker using EAF slag, achieving a clinker composition of 47% alite, 32% ferrite, and 20% belite while replacing 20% of clinker raw materials i.e. limestone, iron and silica source. The hydration behavior and influence of carbonation curing on the reactivity of the ferrite phase were assessed. Results show that the addition of 5% gypsum to the clinker enhanced the hydration rate of alite and ferrite phases, promoting the formation of portlandite, C-S-H and ettringite as the major hydration phases. Typical of ferrite-rich cement, Fe/Al-rich siliceous hydrogarnet was also identified as secondary hydration products of the ferrite phase, formed as a result of the reaction of katoite (formed from ferrite dissolution) with dissolved silica. However, prolonged carbonation exposure led to a decrease in the formation of the hydrogarnet and the decomposition of ettringite, but the mortar’s strength increased with increasing calcium carbonate formation.