Properties of Slightly Alkali-Activated Electric Arc Furnace Slag Concretes and Statistical Evaluation

Abstract

Electric arc furnace slag (EAFS) is a material that emerges as a by-product in iron and steel plants and is in need of evaluation. To ensure its recovery by using it in concrete production, it was replaced 10%, 20% and 30% by weight with cement, and only this part of mixture was activated with alkalis. During the hydration of the cement, alkalinity of the environment increases. In order to facilitate the reaction of EAFS, the pH value of the medium was increased by adding alkaline materials from outside. Replaced EAFS was activated with three different alkali solution levels by changing sodium concentrations (4%, 6% and 8%) and silicate moduli (1 and 2). Alkali solution/binder ratio was kept the same as 0.4 for all slightly alkali-activated mixtures, and the binder dosage was 400 kg/m(3). The effects of the pH degree of the medium were determined by mechanical and permeability tests. Capillary water absorption, water absorption, pressurized water permeability, gas permeability and rapid chloride permeability (RCP) properties were determined, and results were analyzed statistically to know the effect of each variable. 4% sodium concentration and silica module 1 appear to be quite effective in reducing RCP. When the alkali level is too high, the strength decreased and the permeability increased. The visualization of gel formation in the scanning electron microscope image proved that EAFS can be alkali-activated.