Title:
Thermal, Microstructural, and Mechanical Properties of Ternary Blended Geopolymers
Author(s):
S. Sundar Kumar and S. Maheswaran
Publication:
Materials Journal
Volume:
119
Issue:
4
Appears on pages(s):
103-115
Keywords:
calcined lime sludge; characterization studies; fly ash; geopolymer; lime sludge; slag
DOI:
10.14359/51734728
Date:
7/1/2022
Abstract:
Geopolymer (GP) binders are an environmentally friendly alternative to ordinary portland cement (OPC). They can be produced from materials which otherwise would be considered waste and would result in environmental degradation. The objective of this study is to use industrial residues—namely, fly ash (FA), slag cement, and calcined lime sludge (CLS)—as raw materials for geopolymer binder synthesis and to investigate the thermal, microstructural, and mechanical properties of ternary blended geopolymers. This study also focused on replacing calcium-rich slag cement with CLS, a pulp and paper industry residue, the disposal of which is still a concern for the industry. Alkali activator solutions (AAS) responsible for the chemical reactions were used at two levels of concentration. Thermal analysis was carried out by using an isothermal conduction calorimeter and thermogravimetric-differential thermogravimetric analysis (TG-DTG). Microstructural characterization of raw materials and GP products were investigated by using X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy (SEM) with energy-dispersive X-ray analysis (EDAX). The results showed that the reaction characteristics of products formed and strength developed of GP mortars were as in conventional cement mortars, and also proved that CLS is a viable replacement for slag cement in geopolymer. Hence, in this novel work, slag cement and fly-ash-based geopolymers were produced by using CLS as a ternary blend partially replacing slag cement. With slag cement no longer being available free of cost, use of CLS in place of slag cement would not only reduce the cost of geopolymer but also result in a smaller carbon footprint of the product.