Alkanolamines as grinding aids and hydration enhancers in blended cements with iron-rich non-ferrous metallurgy slag

Iron-rich non-ferrous metallurgy slags have been shown to react in cementitious systems. However, grinding of these slags is energy intensive. Therefore, this work investigates the use of secondary (diethanolamine, diisopropanolamine) and tertiary (triethanolamine, triisopropanolamine) alkanolamines as grinding aid (0.025 wt%) for a non-ferrous metallurgy slag and in blended cements with this slag. Improved grinding efficiency of up to 8 % was found. Enhanced slag dissolution was observed for all types, albeit stronger for tertiary variants. The impact on the hydration of blended cements with these slags was studied by addition in the mixing water or by using slag ground with alkanolamines. Increased slag reaction in the presence of alkanolamines was confirmed, forming additional, water-binding, cementitious phases. Yet, compressive strength was either minimally affected (secondary) or decreased (tertiary) when alkanolamines were added in the mixing water. Used as grinding aids, tertiary alkanolamines increased (+5-13 %) the 28 day compressive strength instead.