Comparative study: nanosilica, nanoalumina, and nanozinc oxide addition on the properties of localized geopolymer

Abstract

Due to the enthusiasm of researchers to improve the performance of geopolymers by introducing nanoparticles, which has experienced a rapid increase in recent years, this study compares the effects of nanoSiO2, nanoAl2O3, and nanoZnO on the properties of the geopolymer based on local metakaolin. A detailed comparative analysis of the nano-added geopolymers was conducted using XRD, XRF, FTIR, SEM, MIP, and TG along with mechanical and physical characteristics. For a given compressive strength, the optimized values of nanoSiO2, nanoAl2O3, and nanoZnO were found to be 5%, 2%, and 0.5% respectively. The results of the aforementioned tests had clearly shown an improvement in the microstructure of the geopolymers by addition of all three types of nanoparticles; however, with regard to porosity, the nanoalumina has shown the superior behavior as compared to nanosilica and nanoZnO while with regard to water absorption, the nanosilica had shown the lowest values as compared to other nano-added geopolymers. In addition, Si/Al trends for each nanoparticle with respect to their effect on the compressive strength of the geopolymers have shown different inclinations. An analytical model to predict the compressive strength of the nano-added geopolymers in terms of the density has also been defined. Furthermore, the cost analysis has shown the highest cost reduction factor for nanoZnO geopolymer making it the most economical option as compared to other nanoparticles to achieve the same mechanical strength.