Characterization and acid resistance test of one-part geopolymer from fly ash and water treatment sludge

¹ Chemical Engineering Department, Gokongwei College of Engineering, De La Salle University, Manila, Philippines
² Department of Transdisciplinary Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan
³ Chemical Engineering Department, Ho Chi Minh University of Technology, Ho Chi Minh City, Vietnam.

^* Corresponding author: aileen.orbecido@dlsu.edu.ph

Abstract

Development of geopolymers from wastes or by-products introduces a sustainable approach to replace ordinary Portland cement (OPC)-based concrete with an eco-material of lower green-house gases emissions. However, safety concerns related to the conventional two-part geopolymer has limited large-scale applications of the product. In this context, a novel one-part geopolymer from coal fly ash and water treatment sludge has been presented. The transformation of raw materials to geopolymer was observed by FTIR, SEM and XRD analyses. Acid resistance test has proved that the new binder had great durability against sulphuric acid attack. After 28 days immersion in 5% H₂SO₄ solution, weight of all samples was hardly changed. Compressive strength, on the other hand, has not decreased but significantly increased as curing time increased. The properties were also compared to those of control samples cured in water. It was demonstrated that strong acid immersion did not create any noticeable effect on the weight and strength of one-part geopolymer system developed from coal fly ash and water treatment sludge.