Geopolymer synthesis and performance paving the way for greener building material: A comprehensive study

Abstract

Ordinary Portland Cement (OPC) is renowned for its robustness and endurance in construction, but its manufacturing process incurs substantial energy consumption and leads to significant carbon dioxide emissions. Geopolymers (GP), conversely, represent a synthetic material derived from industrial by-products like calcined materials and slag. This study employs a diverse array of techniques to optimize the formulation of geopolymers and to evaluate their initial state (slump, reactivity) and mechanical characteristics (mechanical strength, density). Materials used are a combination of metakaolin (MK), granulated blast furnace slag (GBFS), and potassium silicate (K2SiO3) as an alkaline reagent (AR). The findings indicate that geopolymers exhibit strength akin to that of Portland cement (even better at early ages, between +16% to +88% higher), thereby positioning it as a credible substitute. The examination of the microstructure through methods such as nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and Thermogravimetric analysis (TGA) reveals that the synthesized material possesses a stable interconnected polymeric 3D-structure. Furthermore, mercury porosity analysis demonstrates the presence of finer pores (nanometric) consistent with a densely packed and closely-knit micelle structure. This study demonstrates that geopolymers blend comprising calcined earth, metakaolin, and slag holds promise as a viable alternative to OPC.