PSI - Issue 70

R. Mohanraj et al. / Procedia Structural Integrity 70 (2025) 358–364

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and durability while using less cement (Li et al., (2022)). The pozzolanic reaction in cementitious composites is accelerated by flash, a highly reactive byproduct of burning coal, which results in mortar that is denser and more resilient (Dezhampanah et al., (2021)). Since they can improve particle packing, reaction kinetics, and overall strength, nanomaterials like nano- TiO₂ have been investigated in cementitious systems in recent years (Döndüren & Al-Hagri, (2022)). Because of its incredibly small particle size and large surface area, nano- TiO₂ alters the mechanical and crystalline structures of cement mortar, affecting its performance (Jafari & Afshar (2016)). The ideal dose levels are essential, though, because too much nano- TiO₂ will cause particle agglomeration, which will degrade the mortar's qualities (Liu et al., (2019); Liao et al., (2023); Lee et al., (2013)). The nano- TiO₂ has the potential to improve mechanical strength, durability, and microstructural refinement, its integration into cement mortar has been extensively researched (Adebanjo et al. (2024)). According to research, calcium silicate hydrate (C-S-H) gel is more likely to develop when nano- TiO₂ serves as a nucleation site for hydration reactions (Zhang, et al. (2025); Mohanraj and Vidhya 2024; Mohanraj et al. 2023; Mohanraj et al. 2022). This increases the density and strength of cementitious materials. According to research by Sastry et al. (2021) and Abdalla et al. (2022), compressive and flexural strength can be improved by adding 1-5% nano- TiO₂, with the best effects seen at dosages of 3-4%. Pathak & Vesmawala (2022) pointed out that too much nano- TiO₂ results in agglomeration, which lessens its efficacy. Joshaghani et al. (2020) research also showed that nano- TiO₂ improves bending resistance by decreasing porosity and improving the interfacial transition zone (ITZ). According to Ying et al. (2017) and Guo et al. (2020) experimental research employing Compression Testing Machines (CTM) has verified that mortar treated with nano- TiO₂ has a more uniform crack distribution and greater fracture resistance. Nano- TiO₂ improves chemical bonding with cement hydration products, according to Chunping et al. (2018) FTIR spectroscopy studies. Staub de Melo & Trichês (2018) XRD analysis revealed a decrease in calcium hydroxide (CH) content and an increase in C-S-H phases, indicating better cementitious qualities. Although nano- TiO₂ improves the characteristics of cement mortar, agglomeration-related strength decrease must be prevented by using appropriate dosage control and dispersion procedures (Han Bet al. (2017); Mohanraj et al. 2024)). By assessing flash-based cement mortar with nano- TiO₂ and concentrating on strength augmentation, structural behavior, and chemical interactions, the current work expands on these findings (Martins et al., 2016)). Flash-based cement mortar with different nano- TiO₂ percentages (1%, 2%, 3%, 4%, and 5%) is the subject of this study. Compressive strength tests and FTIR spectroscopy are used in the study to assess mechanical and structural qualities (Chen et al., (2021)). However, because strength development and phase composition are the main emphasis of the research, hydration investigations, microstructural analysis, and testing of photocatalytic capabilities are not included. It is anticipated that the results of this study will aid in the creation of high-performance cement mortar, which will be useful for advanced building materials, high-strength concrete applications, and sustainable infrastructure projects. This study attempts to offer a long-lasting and reasonably priced substitute for conventional cement mortar by maximizing the nano- TiO₂ content. 2. Materials and Methodology A key ingredient in pozzolanic reactions in concrete, silicon dioxide (TiO₂) is abundant in sand, quartz, and rocks. It combines with calcium hydroxide [Ca(OH)₂] from cement hydration to form calcium silicate hydrate (C -S-H) gel, which increases durability, decreases porosity, and increases strength (Zuhier & Al-Mulali (2025)). Because of its high hardness and thermal stability, TiO₂ also increases resistance against sulphate assaults and freeze -thaw cycles (Shanmugasundaram et al. 2022; Velumani et al. 2023). For this study, Portland cement was sourced from SRM University and characterized using the Blaine method to determine specific surface area (Loganathan et al. (2022)). Cement primarily contains clay, silica, iron oxide, and limestone, with hydration forming C-S-H gel responsible for strength (Pattusamy et al. 2024; K.M. & R. S 2025; Gopalakrishnan et al. 2024). Bogue compounds — C₃S, C₂S, C₃A, and C₄AF — govern early strength, long-term strength, setting time, and sulphate resistance, respectively (Feng et al. (2025)). Coarse aggregates (10 – 40 mm) of 2.6 – 2.9 g/cm³ density and fine aggregates (≤4.75 mm) of 2.5 – 2.7 g/cm³ density were used to enhance the mechanical properties and workability of concrete. Six mixes were prepared with 0%, 1%, 2%, 3%, 4%, and 5% nano- TiO₂, using M25 mix ratio (1:1:2), and cast into cubes, beams, and cylinders. A modified mixing method optimized SP adsorption using poly-carboxylic ether-based superplasticizer (Srivastava et al. (2025)). The dry ingredients were mixed, followed by staged addition of water and SP, and final