Valorization of fly ash as an additive for electric arc furnace slag geopolymer cement

Abstract

The precursors of alkali-activated materials (AAMs) have major effects on their properties. More attention was paid to using by-product precursors such as slag and fly ash (FA) for AAMs, whilst less attention was paid to using another by-product precursor such as electric arc furnace slag (EAFS). The use of EAFS as a geopolymer precursor is still under the development stage. Thus, the current paper aims to study the fresh and mechanical properties, as well as durability of EAFS geopolymer cement activated with NaOH and sodium silicate solution. The durability was studied by two parameters named water absorption and chloride penetration permeability. To improve the properties of EAFS geopolymer cement, EAFS was partially replaced with 15–60 wt% FA. X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were used to analyze the results. The results showed modified properties of EAFS geopolymer cement with the incorporation of FA such as high flowability, high mechanical strength, low water absorption, low charge passed, preventing the formation of microcracks, refining and densifying the microstructure.