Exploring the synergy between aluminum powder and silica fume in enhancing lightweight concrete characteristics

Lightweight concrete effectively maintains structural integrity while subtly reducing the load imposed by traditional dead load limits. The current study aims to investigate the synergistic effects that can result from combining silica fume and aluminum powder in lightweight concrete. Silica fume was added to replace OPC because it has a lower density, significantly reducing the overall density of the concrete. An experimental design approach was used to examine the combined effects of aluminum powder and silica fume. In concrete, silica fume was incorporated at varying proportions to replace cement: 0%, 5%, 10%, 15%, and 20%. As an aerating agent, aluminum powder was added at different proportions, including 0%, 0.1%, 0.2%, 0.5%, and 0.7%. A series of experiments was conducted to assess the fresh, mechanical, and durability characteristics of the concrete, all of which are critical for lightweight concrete. It was observed that adding aluminum powder reduces strength, while silica fume improves it. Specifically, 20% replacement of OPC with silica fume increased compressive strength, split tensile strength, flexural strength, and modulus of elasticity by 7.64%, 5.68%, 4.40%, and 3.30%, respectively. It was also found that adding aluminum powder and silica fume decreases the dry density of the concrete. Models were developed using response surface methodology, and mathematical equations were created to predict response outcomes. All responses were optimized through multi-response optimization, and experimental validation was performed to confirm the optimized results.