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

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:0.5SiO2mol/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 20% mass (Mix D2), then decreased with the increase of CKD contents from 30 to 50% mass. The chemically combined water and combined slag content of activated GGBS-CKD increased with increasing CKD content up to 50% mass (Mix D4). Mix D2 (20% 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 <mml:msubsup>SO42-</mml:msubsup> 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.