Nano-silica and Ground Granulated Blast Furnace Slag Blended Concrete: Impact of Temperature on Stress–Strain Constitutive Model

This research aims to advance the construction industry’s progression by examining the complicated dynamics of concrete combined with nano-silica (NS) and ground granulated blast furnace slag (GGBFS), with the fundamental goal of establishing a reliable stress–strain constitutive correlation. The potential of blended concrete with NS (0–5%) and GGBFS (0–25%) as partial cement replacements at temperatures ranging from 27 to 1000 °C was investigated to address critical issues such as fire damage and durability aspects. The results showed an impactful improvement in the stress–strain characteristics within blended concrete by selectively evaluating stress–strain behaviour together with thorough evaluations of compressive strength, elastic modulus, water sorptivity, sulphate resistance, and water absorption. The results appear at 4% NS and 20% GGBFS, yielding better mechanical, resilient, and micro-structural performance at high temperatures. Amidst deterioration, the blended concrete outperformed the control sample, demonstrating the synergistic benefits of NS and GGBFS in creating a more waterproof and long-lasting concrete structure. In the last phase, the correlation between mechanical properties at ambient (27 °C) and increased temperatures was presented to develop a strong stress–strain constitutive model. This model relates the experimental data well, confirming the intricacies of the created concrete blend. This study not only improves the clarity of the observations into concrete performance but also strengthens the application of this study in real-world circumstances, laying the framework for future construction improvements.