Engineering Properties of Alkali-Activated Mortar Incorporating Electric Arc Furnace Slag: A Case Study of Misurata City, Libya

Abstract

This study investigates the engineering properties of alkali-activated mortar produced with Electric Arc Furnace Slag (EAFS) sourced from a steel factory in Misurata City, Libya, as a sustainable alternative to ordinary Portland cement. EAFS was used as the sole binder at replacement ratios of 0%, 5%, 10%, 15%, 30%, 60%, 80%, and 100%. The alkaline activator consisted of sodium hydroxide (NaOH) at concentrations of 2, 4, 6, and 8 M, combined with sodium silicate (Na?SiO?) at a fixed ratio (R = Na?SiO?/NaOH) of 0.5, while the binder-to-total liquid ratio was maintained at 0.44. Key engineering properties, including flowability, density, compressive strength, and flexural strength, were evaluated after 28 days of curing at 30?°C. The results indicate that an EAFS replacement ratio of 15% yields optimal performance. Increasing NaOH concentration from 2 M to 8 M improves fluidity but reduces density and compressive strength, which is attributed to the formation of portlandite and limited production of calcium silicate hydrate (C-S-H) or calcium-sodium aluminosilicate hydrate (C-(N)-A-S-H) gels due to the reduced availability of Ca²? and Na? ions in EAFS. The cementitious behavior of the slag is also influenced by the presence of tricalcium silicate (C?S), tricalcium aluminate (C?A), and calcium aluminate ferrite (C?AF). This case study demonstrates that locally sourced EAFS from Misurata City can be effectively utilized in alkali-activated mortars, though its engineering properties are highly dependent on activator concentration and replacement level.