Mechanical and environmental performance evaluation of meta-kaolin and silica fume-modified steel fiber embedded concrete: A sustainable construction

• Optimized Concrete Mix – Incorporating 10 % silica fume or metakaolin with 1 % steel fiber significantly enhances compressive, tensile, and flexural strength. • Sustainability Impact – Replacing 15 % OPC with silica fume reduces embodied carbon by 13.33 %, improving eco-strength efficiency. • Economic Viability – Cost analysis shows that higher SF/MK content increases costs, but improved durability justifies the investment. • Predictive Modeling – Response Surface Methodology (RSM) and ANOVA analysis validate mix optimization with high R² values (up to 95.2 %). In this experimental study, mechanical strength, and environmental characteristics of concrete were evaluated. Concrete was prepared by replacing cement with green cementitious material silica fume and meta-kaolin, Additionally, concrete is blended with steel fiber as a means to enhance the concrete characteristics. Response surface methodology was employed for designing the series of experiment and proportions. Two models were constructed in RSM separately, one model consists of meta-kaolin (MK) and steel fiber, while other consists of silica fume (SF) and steel fiber. Findings of both models were compared to each other to study the effects of SF and MK on concrete through the addition of steel fiber. Concrete was tested for compressive strength (CS), split tensile strength (STS), FS (FS), modulus of elasticity (MoE), ultra-sonic pulse velocity (UPV) and symbolized carbon (EC) with eco-strength efficiency (ESE) remained likewise estimated. As per the investigation, it was concluded that addition of 10 % MK with 1 % steel fiber in concrete offers the extreme mechanical strength among the mixes containing MK as a cementitious replacement material and concrete containing 10 % of SF with 1 % of steel fiber exhibits the maximum mechanical strengths among the proportions containing SF in concrete. It was found that concrete containing SF exhibit higher mechanical strength in comparison to concrete in which MK is used as cement supplementary material. Concrete containing 10 % MK or SF reinforced with 1 % steel fiber has the highest ESE. Concrete containing 10 % MK and 1 % steel fiber increases CS, STS, FS and MOE by 14 %, 7.29 %, 8 % and 7.29 % respectively. While concrete mixes containing 10 % SF and 1 % steel fiber enhances the CS, STS, FS and MOE by 19.11 %, 17.23 %, 10 % and 10.06 % respectively in comparison to control mix. Finally, Statistical equations were developed for anticipating the value of each response by using independent variables (MK, SF and steel fiber).