Corrosion Resistance of Bottom Ash and Fly Ash-Based Reinforced Geopolymer Concretes Using Half Cell Potential and Linear Polarization Resistance Methods

Abstract

The production of Portland cement causes environmental pollution due to the amount of carbon dioxide released into the atmosphere. This environmental pollution can be reduced by improving the usage of industrial by-products. Geopolymer is a new concept that does not involve the use of Portland cement as a binder. Geopolymer Concrete (GPC) is formed by using such by-products and produces concrete without using any Ordinary Portland Cement (OPC). It produces the concrete by mixing the Alumino–Silicate source materials such as fly ash or slag with alkali activators such as KOH or NAOH. Due to the wide availability and low cost, industrial waste residuals such as fly ash are commonly used as the source material for the manufacture of GPC. The durability of GPC should be calculated and compared to OPC in order to consider Geopolymer concrete as an alternative to OPC. To achieve this goal, 12 molar Geopolymer concrete and 40 MPa ordinary Portland cement concrete specimens were prepared and tested for corrosion rate. A combination of fly ash and bottom ash was used as the basic source material which is activated by geopolymerization process to be the concrete binder. Instead of using sodium based activators, the alkaline liquids used in this project for the process of polymerization are the solutions of potassium hydroxide (KOH) and potassium silicate (K2SiO3), due to its better contribution on workability and strength. The results have shown that geopolymer concrete exhibited a higher resistance to chloride-induced corrosion; with low corrosion rate and low mass loss percentage, compared to OPC concrete.