Examining the Use of Nano-Silica Modified Self-Compacting Concrete in High-Rise Buildings

Authors: *Unamba, K.U. And Sopakirite, S.

DOI Info: http://doi.org/10.5281/zenodo.21046936

ABSTRACT

The increasing height of modern structures requires concrete with superior workability, strength, and durability. This study evaluates the influence of nano-silica (NS) on the performance of self-compacting concrete (SCC) intended for high-rise building applications. Four SCC mixes containing 0%, 1%, 2%, and 3% nano-silica by weight of cement were prepared and tested for fresh properties, mechanical strength, durability, and time-dependent behavior following EFNARC and ASTM standards. Results show that incorporating nano-silica significantly improves SCC performance up to an optimum dosage of 2%. At this level, slump flow reached 705 mm, the L-box ratio improved to 0.90, and the 28-day compressive strength increased to 55.9 MPa, representing a 21% improvement compared with the control mix. Durability indicators also improved substantially, with chloride permeability reduced by 28%, freeze–thaw mass loss reduced by 34%, and water absorption reduced by 20%. Time-dependent properties, including drying shrinkage and creep were also reduced. However, increasing nano-silica to 3% resulted in marginal reductions in workability and strength, attributed to particle agglomeration and increased water demand. The findings demonstrate that nano-silica enhances SCC performance through accelerated hydration, formation of additional C-S-H gel, and refinement of pore structure. Statistical validation yielded a strong correlation between nano-silica dosage and performance parameters (R2 = 0.93). The study concludes that 2% nano-silica provides the optimal balance between workability, mechanical performance, and durability, making nano-silica-modified SCC a promising material for high-rise construction.

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