Effect of activator type and Pozzocrete waste on the mechanical and microstructural properties of eco-friendly geopolymer incorporating electric arc furnace slag

Abstract

ABSTRACT The precursor type and activator are two primary factors that significantly affect the properties of geopolymers. Most of the previous studies used byproduct materials such as fly ash (FA) and slag as geopolymer precursors, while too limited studies used electric arc furnace slag (EAFS) for this purpose. The EAFS is a type of steel slag, which can be produced when scrap steel is melted. The preliminary usage of EAFS as a precursor in the geopolymer system has not been sufficiently highlighted. To make this come true, the current procedure employed EAFS as a precursor material for the geopolymeric system. Due to superior properties, EAFS was partially replaced with 10–50 wt% pozzocrete (Pz). Two different types of alkaline activators, NaOH and Na2CO3, were used to activate EAFS slurries supported by Pz. The results indicated that the optimal ratio of Pz to be replaced by EAFS to achieve the target properties varies according to the type of activator. The inclusion of 10% Pz exhibited maximum compressive strength when Na2CO3 was used, whilst 50% Pz exhibited maximum compressive strength when NaOH was used. The coexistence between N-A-S-H from Pz and C-(A)-S-H gel from EAFS is the main reason for the enhanced strength.