Green slag cement with nano copper oxide and nano silica: Enhanced antimicrobial and structural properties

Abstract

The global construction industry is facing challenges related to sustainability, environmental impact, and the demand for innovative materials with multifunctional properties. A major concern is the durability of cement structures, which is often compromised by harmful bacteria and algae. These microorganisms accelerate the deterioration of structures, increase maintenance costs, and pose safety risks. Addressing these issues is essential to prolong the life of cement-based structures and reduce their environmental and carbon footprint. Cement in moist environments is particularly vulnerable to microbial growth, leading to structural weaknesses and degradation. This degradation necessitates costly repairs, shortens the lifespan of infrastructure, creates a threat to human lives, and contributes to increased carbon emissions. To tackle these challenges, researchers have tried to develop low-carbon cement ((green cement) with antimicrobial properties. Nanomaterials like nano-copper oxide (nCuO) and nano-silica (nSiO₂) have shown great potential in enhancing both the structural performance and microbial resistance of green cement. When nanomaterials, nCuO is incorporated into Portland slag cement (PSC), which already has a lower carbon footprint compared to traditional cement, enhances antibacterial and antialgal properties but adversely impacts the mechanical performance and to counter the adverse effect of nCuO, nSiO2 added to improve the mechanic performance. PSC is known for its ability to reduce industrial waste and CO₂ emissions, and the addition of nCuO and nSiO₂ makes it an even higher-performance material. Effects of nCuO and nSiO₂ on PSC have been studied by using isothermal calorimetry to assess hydration kinetics, X-ray diffraction to observe composition changes during hydration, scanning electron microscopy (SEM) to analyze microstructural changes, and mechanical testing to evaluate the strength of the material. The effectiveness of antimicrobial properties is studied in lab and field experiments. The results revealed improved compressive strength and significant resistance to bacterial and algal growth. The combination of nCuO's antimicrobial properties and nSiO₂'s ability to enhance the cement's strength created a synergistic effect that optimizes both performance and durability. Additionally, the study proposed a model to better understand the interaction between these nanomaterials, offering valuable insights into the mechanisms of hydration and microbial inhibition.