Reactivity of modified iron silicate slag as sustainable alternative binder

Abstract

A possible solution to decrease the CO2 footprint caused by cement industry and to enhance the transition to circular economy is to use slags as Supplementary Cementitious Materials (SCM). The study presented here focuses on valorizing and investigating the reactivity and mechanical properties of blended binder systems combining modified iron silicate (MFS) slag and Ordinary Portland cement (OPC). MFS slag is a fumed by-product synthesized during the production of copper metal (Cu). This slag can be used as possible alternative SCM due to its pozzolanic behavior. To study the replacement level in relation to reactivity and strength development, replacement levels of 15, 30 and 50 wt% of MFS-slag in OPC are analyzed. The work can be divided into two categories, 1) assessing the reactivity through thermogravimetric analysis (TGA) and 2) evaluating the compressive strength (as a function of time) of mortar with MFS-slag after 2, 7, 28 and 90 days. TGA at 7, 15, 28 and 90 days allows to determine the reduction of portlandite (CH) content which gives an indication of the pozzolanic reactivity. Reactivity of the MFS-slag blended systems is also determined relative to inert filler blended systems to discern between the reactive behavior of the MFS-slag and the filler effect