Optimization of Mix Proportions in an Experimental Study of Control Variables Impacting the Strength Properties of Blended Concrete with Metakaolin and Steel Slag

The present investigation is undertaken with the intent to utilize Taguchi method of structured empirical approach with an L16 orthogonal array to optimize the strength and fresh concrete qualities by combining different ratios of steel slag and metakaolin. Concrete's mechanical integrity can be considerably increased by adding mineral additions like fly ash and silica fume, according to earlier studies. In an effort to create cement formulations that are more sustainable, increased attention is being paid to using waste-derived materials and post-industrial outputs as reinforcing agents. To augment the overall engineering characteristics of concrete, metakaolin and steel slag are utilized in this work as partial substitutes for cement and M-sand, respectively. By using steel slag in place of fine aggregate and metakaolin in place of cement, the main objective is to forecast and improve the unique qualities of concrete. Cementitious material to water ratios (w/cm) at 0.36, 0.38, 0.40, and 0.42; metakaolin to cementitious material ratios (M/cm) at 10%, 15%, 20%, and 25%; and steel slag to fine aggregate ratios (SS/FA) at 10%, 20%, 30%, and 40%, are the control factors. After seven and twenty-eight days, the concrete's fresh and hardened qualities were assessed. Results demonstrate that metakaolin, when utilized as a cementitious substitute, contributes to a notable enhancement of up to 10% in the compressive strength at 28 days. Moreover, steel slag sand greatly increases split tensile strength at this level while making a little contribution to compressive strength up to 30% replacement. Comparing the outcomes with a control mix showed how these substitutions could enhance the performance of the concrete.