Advanced Geopolymer-Based Composites for Antimicrobial Application

Abstract

In most studies about geopolymeric materials used in construction, the antibacterial properties of the building materials are treated as secondary features. Today, antimicrobial properties are a key feature in many building applications. The main objective of this article is to summarize the state-of-the-art in the area of design, development, and applications of nanoparticles as additives to geopolymer composites used in construction to improve their physical mechanical properties and induce a potential antibacterial effect, protecting them against alkali-resistant bacteria. On the basis of the literature and authors' experience, the most important methods of obtaining especially the porous geopolymers, of nanomaterials used as additives, with potential antibacterial effect but also the potential mechanism of action against bacterial development were presented. The main findings show that using graphene oxide (GO) in geopolymer composites, but also other nanoparticles such as silver (Ag), zinc oxide (ZnO), silica (SiO₂), titanium dioxide (TiO₂), copper (Cu) as additives, is an effective way to induce a potential antibacterial effect and to improve the physical and mechanical properties in building materials.

Keywords: antibacterial; building materials; geopolymers; graphene oxide; nanoparticles.

Figure 1

Schematic image of antimicrobial mechanism at surface of materials, caused by ion exchange.

Figure 2

SEM images of the GO: (a) GO; (b) GO with fly ash; (c) GO with silver; (d) GO with ZnO at ×1000 magnifications.

Figure 3

Schematic representation of the surface of the geopolymeric material after acid attack followed by microbial action and the potential antibacterial mechanism of the graphene oxide nanosheets.

Figure 4

Disk diffusion assay on Porphyromonas gingivalis (Pg), Streptococcus mutans (Sm), Staphylococcus aureus (Sa) and Escherichia coli (Ec) for the GO powders [21].