Factorial experimental design for developing sustainable concrete incorporating metakaolin and sintered fly ash aggregates

The impact of the usage of sintered fly ash aggregates (SFA) as a partial substation of coarse natural aggregates (CNA) and metakaolin (MK) as partial replacement cement has been assessed in this study. To achieve this objective, a full factorial design has been adopted with choosing factors SFA(%) and MK(%) and compressive strength (CS), split tensile and flexural strength, water absorption (WA), volume of voids (VV) and density are selected as selected responses of this investigation. The levels of MK(%) are 0%, 10%, 15%, and 20%, and for the other factor SFA(%), 0%, 15%, 30%, and 45% are chosen as levels. The procedures of the general factorial approach have been followed for analysing the experimental outcomes. Analysis of variance (ANOVA) results and individual, contour, main effects and interaction plots have been used for annotation of the findings of the current research. The study depicts that the main effects of SFA(%) and MK(%) considerably influence the above-mentioned responses; however, the interaction of the said factors has the least significant impact on chosen concrete properties. Furthermore, the study reveals that a 26% reduction in CS, a 14% decline in STS, and a 20% decrease in FTS has been witnessed with the inclusion of SFA up to 45%, which can be compensated by the usage of 15% MK in SFA incorporated mix. Similarly, a reduction in density and rise in WA and VV of concrete is witnessed with the use of 45% SFA owing to inferior characteristics of SFA as compared to CNA. However, this degradation in concrete characteristics has been marginalised by using the beneficial effects of MK. The study recommends for adaptation of 30% SFA and 15% MK in making sustainable concrete for practical usage.