Thermal Resistance of Alkali Activated Binders Synthesized Using the Fly Ash and Steel Slag

Abstract

The thermal resistance of alkali-activated binders based on fly ash (FA), electric arc furnace slag (EAFS) and their FA/EAFS blends was assessed. Compressive strengths of samples before and after firing were measured. The samples were characterized by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), energydispersive X-ray spectra (EDS), thermal (TG/DTA) analysis. Besides, the sintering shrinkage were recorded by thermomechanical analyzer (TMA) during non-isothermal sintering up to 900 ºC with heating rate of 15 º/min, in an air atmosphere. The main reaction products in FA and EAFS based alkali activated binders are the sodiumalumino-silicate-hydrate (N–A–S–H) and calcium-alumino-silicate-hydrate (C-A-S-H) type gels, respectively. FA/EAFS based binders are characterized by the presence of N-A-S-H gel with the high content of Ca. The EAFS based binders exhibited superior performances in terms of compressive strength than FA based binders. Thermal resistance of FA based binders was improved by the slag addition. This research was supported by a Ministry of Science of Montenegro under the contract No. 01-460.