Geopolymer Concrete with Nano Silica: A Review on the Impact of Sodium Hydroxide Solution Molarity

Abstract

Geopolymer concrete is gaining popularity as a sustainable substitute for conventional cement concrete, primarily attributed to its reduced carbon footprint and enhanced properties. As geopolymer technology advances, ongoing research is directed towards optimizing mix designs, clarifying long-term performance traits, and broadening the material’s range of applications. The practical application of geopolymer concrete faces a limitation in the form of heat activation at different temperatures. Several studies have undertaken the use of nanoparticles to overcome this constraint in optimal proportion. This review provides a thorough examination of the recent research on the integration of nano silica in geopolymer concrete, while also exploring the impact of varying sodium hydroxide solution molarity levels on microstructures and mechanical properties. The findings suggest that the inclusion of an appropriate percentage of nano silica enhances various properties of geopolymer concrete. As the molarity increases it is evident that, properties such as compressive strength, tensile strength, flexural strength, and bond strength exhibit parallel improvements. Upon analyzing various studies, 14M NaOH solution with alkaline-to-binder ratio of 0.4 exhibited superior performance. An accelerated rate of polymerization and the conversion of amorphous compounds into crystalline ones are revealed by applying highly reactive analytical techniques such as XRD, SEM and EDS to geopolymer concrete.