In the quest to enhance the performance of cementitious materials, researchers have turned to nanosilica (NS) as a promising supplementary cementitious material (SCM). However, its high reactivity and surface area can sometimes hinder the fresh-state properties and long-term strength development of these materials. A recent study, led by Andréia de Paula from the University of Brasilia, Brazil, explores a more environmentally friendly approach to functionalizing NS to optimize its use in cement-based composites.
Published in ‘Case Studies in Construction Materials’ (translated to English as ‘Case Studies in Construction Materials’), the research focuses on the impact of replacing Portland cement with functionalized nanosilica (NSF) on the hydration and performance of cement pastes and mortars. The study proposes a novel method of direct surface functionalization using (3-aminopropyl)triethoxysilane (APTES) and a shrinkage-reducing additive (SRA), eliminating the need for additional chemical solvents.
The research team conducted a comprehensive experimental program on seven cementitious formulations, evaluating hydration kinetics, portlandite (CH) and calcium silicate hydrate (C-S-H) contents, pore structure, and compressive strength. The results demonstrated that NS functionalization delays cement hydration, reduces the amount of CH due to the pozzolanic reaction, and lowers the total porosity of the pastes compared to the reference paste.
“Our findings indicate that replacing 1% of cement with NS or NSF appears to be the optimal replacement rate,” said de Paula. “This level of cement replacement significantly affects the composite’s performance, offering a balance between enhanced strength and reduced porosity.”
The study’s implications for the energy sector are substantial. Enhanced cementitious materials can contribute to more durable and efficient structures, reducing maintenance costs and extending the lifespan of energy infrastructure. The use of functionalized NS can also lead to more sustainable construction practices by reducing the amount of Portland cement required, which in turn lowers the carbon footprint of construction projects.
As the construction industry continues to seek innovative solutions to improve the performance and sustainability of building materials, this research offers a promising avenue for further exploration. The functionalization of NS with APTES and SRA presents a more environmentally friendly alternative to conventional methods, paving the way for advancements in cement technology.
The study’s findings highlight the importance of optimizing the replacement level of Portland cement with NS or NSF to achieve the best performance in cementitious composites. This research not only contributes to the scientific community but also provides practical insights for industry professionals looking to enhance the durability and efficiency of their projects.
In the words of de Paula, “This research is a step towards more sustainable and high-performance construction materials, and we hope it will inspire further innovation in the field.”