Explore the Opportunity of Utilizing Some Wastes as an Antibacterial Materials in Construction Applications

Building materials nature is antibacterial materials, but the porosity in this material is considered as proper site to hide bacteria. Construction materials deterioration caused by microorganisms poses a critical issue in the field of sustainability of cementitious infrastructures that face harsh biological conditions. From this fact, antibacterial materials are added to prevent the hazards of bacteria in such materials. The purpose of this work is to utilize antibacterial materials with low cost derived from waste materials that have the same effect as pure materials in killing or inhibiting the growth of bacteria. Three waste materials (copper -based materials, zinc oxide, and eggshell (ESP)) were selected as antibacterial materials. Since the construction materials encountered water and air, the selected bacteria were Staphylococcus aureus and Escherichia coli. Two approaches were proposed for use in building materials: the first involves adding antibacterial material to the mortar, while the second involves mixing antibacterial material with epoxy that is applied to the surface of the construction material as a coating. Energy dispersive X-ray spectrometry (EDS) analysis was used to confirm the chemical suitability and purity of selected waste-derived antibacterial materials. The tests performed on the physical characteristics support the earlier conclusions related to the antibacterial activities of both systems. The epoxy coatings tested did not possess any porosity or absorption property, thus confirming the assumption that they create a compact and impermeable medium minimizing the risk of moisture penetration and thus can be viewed as a feasible option concerning their antibacterial characteristics. The use of waste materials in cement-based compounds (especially CuO) allowed reducing both porosity and water absorption due to a filling effect preventing free spaces, which interrupts water-borne and air-borne bacteria infiltration. In general, the results confirm that the protective ability of both types of the systems depends not only on the ability of the additive to destroy bacteria but also on the efficiency of the structure obtained. Agar diffusion and colony-forming units (CFU) techniques were used for evaluating the antibacterial activity of waste-derived materials against the aforementioned bacterial species. Based on the experimental findings, in cementitious composites, all investigated waste-derived antibacterial materials display antibacterial activity. Waste-derived ZnO demonstrates maximum inhibition towards S. aureus bacteria, whereas ESP exhibits maximum inhibition toward E. coli. Copper-based materials exhibit robust and reliable antibacterial performance against both species. Most importantly, copper based materials are able to inhibit bacterial growth in cementitious composites completely. Moreover, eggshell powder shows excellent antibacterial performance. Epoxy-based specimens demonstrate that all investigated waste-derived antibacterial materials retain their antibacterial ability when used as coating additives, confirming their applicability in surface applications for microbially corrosion protection purposes in construction applications. Cu waste had the highest result. It can be concluded that both approaches can be applicable, but the waste material should be selected carefully.