Concrete is the most used material for the construction of millions of structures around the world. Cementitious structures are often exposed to high humidity environments and the attack of atmospheric agents, such as acid rain, which make them vulnerable to microbial attachment with consequent colonization and deterioration over time. In the light of these considerations, the researchers turned their attention to designing green and sustainable alternative materials that exhibit similar characteristics to the traditional concrete by using nanotechnologies.
Concrete is the most used material for the construction of millions of structures around the world. Although it plays a crucial role in building development, it is considered an environmental pollutant due to the CO2 emissions resulting from its production [1][2][21,22]. Furthermore, cementitious structures are often exposed to high humidity environments and the attack of atmospheric agents, such as acid rain, which make them vulnerable to microbial attachment with consequent colonization and deterioration over time. In the light of these considerations, the researchers turned their attention to designing green and sustainable alternative materials that exhibit similar characteristics to the traditional concrete by using nanotechnologies [1][21]. It is well known that stains on concrete walls and building facades are due to biodegradation phenomena and cement structures for irrigation and sewerage, which usually arise from the growth of cyanobacteria, fungi, and algae [3][4][23,24]. The microbial growth and microorganism present on the concrete surface are closely related to pH values, climatic exposure, and nutrient availability [5][25]. In addition, as previously mentioned, acid rains and air pollution can promote microbial development due to the formation of nitrogen or sulfur-containing compounds [6][7][26,27]. Some different mechanisms in which microorganisms can contribute to concrete deterioration are reported [8][28]. Physical deterioration caused by the bacteria proliferation, which leads to the mechanical breakage of concrete structures, aesthetic worsening due to biofilm formation on building surfaces, and chemical corrosion, deriving from the elimination of metabolites, were considered the main routes of degradation [6][26]. All these factors that negatively affect aesthetic characteristics, mechanical properties, and the stability of concretes also involve additional costs for repairing and renovating constructions. For these reasons, researchers tried to develop alternative and innovative cementitious materials that could show antimicrobial, antibacterial, and antifouling properties by using additives to the cement paste having antimicrobial properties against one or more microorganisms without affecting the mechanical properties of the concrete material.
All antibacterial agents for concrete protection mentioned are summarized in Table 1.
Antibacterial Agents | Authors | Ref. | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
ZnO and MgO NPs | Singh et al. | [1] | [21] | ||||||||||||
Metal zeolites and antibacterial polymeric fibers | De Muynck et al. | [9] | [29] | ||||||||||||
Epoxy resins | Kong et al. | [10] | [30] | ||||||||||||
Quaternary ammonium compounds | Javaherdashti et al. | [11] | [31] | ||||||||||||
Halogenated complex | Qiu et al. | [12] | [32] | ||||||||||||
Metal oxide, silver, and tungsten powder | Plutino et al. | [13] | [33] | ||||||||||||
CuO, Cu | 2 | O, ZnO, TiO | 2 | , Al | 2 | O | 3 | , and Fe | 3 | O | 4 | nanoparticles | Sikora et al. | [14] | [34] |
Silver nanoparticles in commercial silica-based coating | Nam, K.Y. | [15] | [35] | ||||||||||||
ZnO, TiO | 2 | , SiO | 2 | nanoparticles | Dyshlyuk et al. | [16] | [36] | ||||||||
SiO | 2 | –Ag nanohybrid compounds in acrylic coatings | Le et al. | [17] | [37] | ||||||||||
Silver nanoparticles in N-SiO | 2 | nanocarriers | Dominguez et al. | [18] | [38] | ||||||||||
BiOCl | x | Br | 1−x | micro flowers | Gao et al. | [19] | [39] | ||||||||
TiO | 2 | nanoparticles, fluorine silicon sol | Zhu et al. | [20] | [40] | ||||||||||
TiO | 2 | nanoparticles | Verdier et al. | [21] | [41] | ||||||||||
TiO | 2 | modified with carbon and nitrogen | Janus et al. | [22] | [42] | ||||||||||
TiO | 2 | and ZnO nanoparticles in addition to polyethylene glycol (PEG) | Dehkordi et al. | [23] | [43] | ||||||||||
Fe | 2 | O | 3 | contained in steel slag of an industrial induction furnace | Baalamurugan et al. | [24] | [44] | ||||||||
Fly ashes recycled by alkali activation process supported with Zn | Rodwihok et al. | [25] | [45] | ||||||||||||
Metakaolin-based geopolymer cement loaded with 5-chloro-2-(2,4-Dichlorophenoxy) phenol | Rubio-Avalos, J.C. | [26] | [46] | ||||||||||||
Metakaolin-based geopolymer cement loaded with glass waste | Dal Poggetto et al. | [27] | [47] | ||||||||||||
Zinc particles or zinc doped clay particles | Roghanian et al. | [28] | [48] | ||||||||||||
Granular activated carbon and fundamental oxygen furnace steel slag particles, copper, and cobalt as inhibitory metals | Justo-Reinoso et al. | [29] | [49] |