Performance analysis of structural lightweight aggregate concrete modified with a combination of nano-silica and forta polymer fibers

Recently, Structural Lightweight Aggregate Concrete (SLWAC) has gained significant attention as a viable solution for reducing structural dead weight and mitigating seismic structural demands in earthquake-prone regions. However, its widespread application has been hindered by its diminished strength and durability compared to normal-weight concrete. This study aims to investigate the synergistic effects of Nano-Silica (NS) and Forta polymer fibers on the mechanical and physical properties of SLWAC. Unlike prior works focused on isolated additives or normal-weight concretes, this study provides a comprehensive experimental evaluation of combining varying Forta fiber contents with NS in Lightweight Expanded Clay Aggregate (LECA)-based SLWAC, concurrently addressing compressive, tensile, flexural, and water absorption properties to determine an optimal balance between strength and durability. Accordingly, lightweight concrete was developed using LECA modified with NS at 3 wt% of cement, and Forta polymer fibers at volume fractions of 0%, 0.45%, 0.68%, and 0.9%. A total of 144 cubic, cylindrical, and flexural beam specimens were cast and tested. Compressive strength was evaluated at 7, 14, and 28 days, while tensile strength, flexural strength, and water absorption were determined at the 28-day mark. The results indicated that the combination of NS and Forta fibers significantly enhanced the performance, with increases in compressive, tensile, and flexural strengths by up to 44%, 77%, and 101%, respectively. Furthermore, water absorption of concrete was reduced by up to 42% through the inclusion of these two additives. Radar chart analysis identified the mix design containing 3 wt% NS and 0.68 vol% Forta fibers as the optimal proportion, providing an ideal balance between strength and durability. The findings of this research recommend the integrated use of NS and Forta polymer fibers as an effective strategy for upgrading the performance of SLWAC in structural engineering applications.