Preparation and Characterization of an Eco-Friendly Binder from Alkali-Activated Aluminosilicate Solid Industrial Wastes Containing CKD and GGBS

Abstract

This work aims to prepare an eco-friendly binder from alkali-activated aluminosilicate solid industrial wastes. Eco-friendly binders provide a solution to the present ecological problem of producing non-portland-cement binders. Cement kiln dust (CKD) and ground granulated blast-furnace slag (GGBS) by-products were used to prepare the binder from alkali-activated GGBS-CKD mixed with XNa2O:.5SiO2 mol/kg. The characteristics of the prepared binder were studied using different techniques such as FTIR, DTA/TGA, XRD, and SEM. The compressive strength and bulk density of alkali-activated GGBS-CKD binders increased with increasing CKD contents up to 2% mass (Mix D2), then decreased with the increase of CKD contents from 3 to 5% mass. The chemically combined water and combined slag content of activated GGBS-CKD increased with increasing CKD content up to 5% mass (Mix D4). Mix D2 (2% mass of CKD) is the optimum mix composition. Ca(OH)2 (CH) and CaCO3 containing CKD disintegrated the aluminosilicate matrix of GGBS. CH acts as a Ca2+ ion source to accelerate the pozzolanic activity to form rigid spheres of the compact massive matrix of (N, C)–A–S–H gel having low porosity. In addition, CKD has higher alkali and SO42− content, which makes CKD an excellent activator to enhance the dissolution of GGBS to release silicate, aluminate, and/or aluminosilicate species and improve the alkali-activated network gel matrix formation.