PSI - Issue 70

Suresh Kumar Verma et al. / Procedia Structural Integrity 70 (2025) 327–334

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consistent performance in structural and general-purpose concrete. The cement was tested for specific gravity, fineness, and setting time to ensure it met IS requirements. The SEM and EDS of OPC is shown in Fig. 1.

Fig. 1. (a) SEM; (b) EDS of OPC

• Nano-Silica (SiO 2 ) Amorphous Nano-Silica (SiO 2 ) with a particle size range of 20 – 30 nm and purity greater than 99% was used. It was procured in a powdered form and dispersed in water using ultrasonication to prevent agglomeration. Nano-silica is highly reactive due to its amorphous structure and large surface area, and it acts as both a filler and pozzolanic material. It reacts with calcium hydroxide (CH) to form additional calcium silicate hydrate (C-S-H), thereby refining the microstructure and enhancing mechanical properties. The SEM and EDS of Nano-Silica is shown in Fig. 2.

Fig. 2. (a) SEM; (b) EDS of Nano-Silica

• Nano-Alumina (Al 2 O 3 ) Nano-Alumina (Al 2 O 3 ) in the α - phase, with a particle size less than 50 nm, was used. The α -phase ensures stability and high thermal resistance. NA acts as a nucleating agent and contributes to early-age strength development. It was incorporated in a dry form and mixed using high-shear mixers to achieve uniform dispersion. The material was characterized using BET surface area analysis and SEM to verify morphology and dispersion potential. The SEM and EDS of Nano-Alumina is shown in Fig. 3.