Analytical and experimental study on the behavior of self‐compacting geopolymer concrete with nanosilica

Abstract This study investigates the effects of nanosilica (NS) addition on self‐compacting geopolymer concrete (SCGC), focusing on mechanical properties, microstructure, durability, and flexural behavior of the beam. Optimizing the dosage of NS and its impact on SCGC's performance is cardinal in advancing sustainable and resilient concrete construction practices. Fly ash and ground granulated blast furnace slag were used as primary binders, with NS incorporated at replacement levels of 0%–6% (by weight of binder) at 1% intervals. Tests were conducted on fresh properties (slump flow, V‐funnel, and L‐box), mechanical properties (compressive, split tensile, and flexural strength), durability (water absorption, sorptivity, rapid chloride penetration, acid and sulfate resistance), and microstructural characteristics (scanning electron microscope [SEM], x‐ray diffraction [XRD], and Fourier transform infrared [FTIR]). The structural performance of beam specimens was also compared with ANSYS finite element analysis. The results indicate that up to 3% NS addition leads to enhanced compressive, split tensile, and flexural strengths, attributed to microstructure refinement. However, beyond the 3% addition, the mechanical properties decline due to the NS agglomeration. NS‐3% samples exhibit reduced water absorption rates, improved resistance to chloride ion penetration, and minimal deterioration against acid and sulfate attacks. SEM analysis confirms a denser microstructure in NS‐3% samples, while XRD and FTIR analysis indicate optimal particle dispersion and enhanced chemical bonding. The experimental values were slightly higher with deviations of 3.44%–5.74% for load and 1.94%–5.3% for deflection, indicating a strong correlation. Overall, integrating NS up to 3% enhances SCGC's mechanical properties, microstructure densification, and chemical bonding, promising improved durability and long‐term performance.