Fly ash and ceramic residue-based geopolymer mortars

Abstract

A binary geopolymer based on fly ash and ceramic residue was developed under ambient water curing. The alkaline medium comprises commercial Na2SiO3 and NaOH with concentration of 10 M and 12 M. Analyses were carried out to characterize the raw materials and their geopolymer properties. Characterization of materials was conducted through x-ray diffraction (XRD), x-ray fluorescence (XRF) and scanning electron microscope (SEM). The compressive strength, porosity and abrasion rates were measured to determine geopolymer performance. The ceramic residue consists mainly of SiO2 and Al2O3, which is similar to fly ash. Among the specimens, the highest compressive strength produced from the specimens was 25.2 MPa at the age of 28 days. This highest strength was followed by the lowest water absorption and abrasion rate, which are 1.99% and 0.007 mm/min, respectively. The microstructure showed geopolymer matrix with some unreacted particles from ceramic residue powder. There were no signs of efflorescence observed on the geopolymer specimens. Each mix demonstrated a slight increment in density and reduced the porosity during the curing period.