Assessment of select direct and indirect pozzolanic reactivity test outcomes with robust regression and ranking analysis

The use of pozzolanic materials as a sustainable partial replacement option for portland cement in concrete has been extensively studied over the last few decades. This study aimed to assess the pozzolanic reactivity of seven different powdered materials: pottery cull, brick powder, lightweight aggregate fines, class C fly ash, silica fume, glass powder, and dolostone. Pozzolanic reactivity was evaluated using seven different direct and indirect methods, including the Frattini test, strength activity index (SAI), ultrasound pulse velocity index (UPVI), thermogravimetric and differential thermal analyses (TG/DTA), calorimetry, electrical conductivity, and pH. Robust correlations and a ranking analysis were performed to evaluate the relationship and efficiency between various direct and indirect test methods. Results of the robust regression analyses showed that Frattini and TGA, SAI and electrical conductivity, SAI and calorimetry, and UPVI and calorimetry were well correlated, suggesting that these methods may be suitable alternatives to each other. According to the ranking method, electrical conductivity and calorimetry are the most rapid and efficient methods for the assessment of different pozzolans in comparison to other longer-duration test methods examined in this study.