Impact of NaOH and Na2SiO3 on Concrete Strength Prediction Using Multivariate Data and Machine Learning

With the growing focus on sustainable construction materials, exploring alternatives to ordinary Portland cement (OPC) is becoming increasingly important due to its significant carbon emissions. Fly ash-based geopolymer concrete has emerged as a promising alternative, offering comparable or even enhanced compressive strength without the use of OPC. This study investigates the influence of various materials used in geopolymer concrete, specifically focusing on the effects of sodium silicate (Na2SiO3), sodium hydroxide (NaOH), fly ash, and aggregates on compressive strength. Employing the SHAP (Shapley Additive Explanations) method, the research identifies key features that contribute to the predictive modeling of compressive strength in fly ash-based geopolymer concrete. The analysis reveals that specific materials, such as age, Na2SiO3, and fly ash, negatively impact compressive strength, with age showing the highest negative effect (-10.09). Conversely, cement and superplasticizer exhibit significant positive influences, with cement contributing a maximum impact of +3.04. Furthermore, the interaction between NaOH and Na2SiO3 is explored, highlighting that while NaOH does not significantly affect compressive strength (SHAP value of +0.00), Na2SiO3 plays a crucial role in enhancing strength (SHAP value of +0.12). The study also investigates the relationship between the NaOH/Na2SiO3 ratio and compressive strength, revealing
the importance of maintaining an optimal balance for achieving maximum performance. The findings suggest that careful adjustments to the mix design can enhance the mechanical properties of geopolymer concrete. By understanding the interactions between different materials and their contributions to compressive strength, this research provides valuable insights for optimizing geopolymer concrete formulations, contributing to advancements in sustainable construction practices. The results provide the potential of the SHAP method as a powerful tool for feature importance analysis in predicting material performance, guiding future research and practical applications in

Keyword: Geopolymer, Compressive Strength, Fly Ash, Sodium Silicate (Na2SiO3), Sodium Hydroxide (NaOH), Sustainable Construction