PSI - Issue 70

R. Mohanraj et al. / Procedia Structural Integrity 70 (2025) 401–408

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FTIR spectra for various SiO₂ percentages. While the Si -OH stretching at 3200 – 3600 cm⁻¹ suggests hydroxyl groups impacting hydration, the significant Si-O-Si stretching vibration at 1000 – 1100 cm⁻¹ validates silica integration. Peak intensity and shift variations point to higher SiO₂ content , pozzolanic processes, and polymerization. A stronger silica network is confirmed by the enhanced Si-O-Si peak as silica increases, enhancing material strength. Hydration and moisture retention are impacted by variations in hydroxyl-related peaks. If there are peaks in the 1400 – 1500 cm⁻¹ range, they might be a sign of carbonation effects that affect durability. Chemical alterations are further highlighted by the decrease or elimination of specific peaks. The silica and hydration potential are strengthened by the overall successful SiO₂ integration confirmed by the FTIR data. Nano- SiO₂'s small size, spherical shape, and uniform dispersion enhance cement strength by accelerating pozzolanic reactions and increasing C-S-H gel formation. FTIR confirms this with stronger Si – O – Si peaks and reduced OH bands, indicating improved hydration, reduced porosity, and a denser, more durable microstructure essential for high-performance concrete. 5. Conclusion This work thoroughly examined how Nano- Sio₂ particles affect cementitious materials against compression and microstructural characteristics. Improved particle packing and decreased porosity are two benefits of Nano silica's pozzolanic reactivity, which speeds up the hydration process and creates more calcium silicate hydrate (C-S-H) gel. The results for compressive strength show that adding Nano- Sio₂ gradually increases strength up to an ideal threshold. Beyond this limit, too much Nano- Sio₂ causes particle accumulation, which impairs strength properties by increasing water consumption and causing uneven dispersion. At the microscopic level, the FTIR analysis provides structural reinforcement by further confirming the decrease of calcium hydroxide and the improved development of C-S-H phases with the increasing silica content. Overall, the structural performance of cementitious composites is ideally improved by the addition of Nano-SiO ₂ in small, regulated amounts. This study offers insightful information about the usage of Nano-SiO ₂ in high performance and sustainable concrete applications, where strength and durability are still major challenges. Future studies could concentrate on improving dispersion methods and investigating different admixtures to further improve the functionality of concrete modified with nano- SiO₂. Up to an ideal quantity, the CTM test results showed a steady increase in the compressive strength with nano silica mixing up to 4%, after that, a fall was noted. The samples with well-dispersed Nano silica and a suitable dosage had the maximum compressive strength. The results of this test offer important information about how to best adjust the number of nano silica, the duration of dispersion, and the dosage of superplasticizer for improved mechanical qualities in cement-based products. Acknowledgements The authors gratefully acknowledge the financial support provided by the SRM Research and Development Centre through the SEED Grant (SRMUH/R&D/SM/001) for carrying out this research work. The corresponding author also extends sincere thanks to SRM University, Delhi-NCR, Sonipat campus, for their partial financial support (Letter, dated 24.12.2024) in terms of registration fee to attend the International Conference on Structural Integrity and Interactions of Materials in Civil Engineering Structures. References Ardalan, R. B., Jamshidi, N., Arabameri, H., Joshaghani, A., Mehrinejad, M., Sharafi, P., 2017. Enhancing the permeability and abrasion resistance of concrete using colloidal nano-SiO 2 oxide and spraying nanosilicon practices. Construction and Building Materials, 146, 128-135. Balapour, M., Joshaghani, A., Althoey, F., 2018. Nano-SiO 2 contribution to mechanical, durability, fresh and microstructural characteristics of concrete: A review. Construction and Building Materials, 181, 27-41. Cui, Z., Zhao, H., Song, J., Liu, W., Zhang, S., Li, W., 2024. Preparation of ester-modified nano-SiO 2 /silicate coatings and its application in the impermeability of concrete. Construction and Building Materials, 455, 139217. Fan, C., Zheng, Y., Zhuo, J., Du, C., Hu, S., 2024. Study on mechanical and bonding properties of nano-SiO 2 reinforced recycled concrete: macro test and micro analysis. Journal of Building Engineering, 94, 109877. Flores, I., Sobolev, K., Torres-Martinez, L. M., Cuellar, E. L., Valdez, P. L., Zarazua, E., 2010. Performance of cement systems with nano-SiO 2 particles produced by using the sol – gel method. Transportation research record, 2141(1), 10-14.