Using particle composition of fly ash to predict concrete strength and electrical resistivity

This paper uses a new approach where fly ash is characterized on a particle-by-particle basis using automated scanning electron microscopy. The particle data is then analyzed with principal component analysis (PCA) to find interrelationships among the particle chemical composition for 20 different fly ashes. Consistent trends were observed in 20 fly ashes. These trends from PCA were verified by making comparisons of these trends for individual particles. One application is introduced using this particle data. Each particle is categorized into four broad groups with a limited chemical composition. These four groups were found in different proportions in the different fly ashes investigated. Compressive strength and surface electrical resistivity were measured from concrete mixtures made with these fly ashes and the four groups correlated with the performance in concrete. This finding is an important step to develop a more general classification of fly ash based on the individual particle make-up, which helps to optimize the mixture design and also benefits the sustainable concrete by increasing the effectiveness of industrial by-waste usage.