Classifying aggregates is typically based on their geological origin, size, shape, unit weight, and other characteristics. Infrared spectroscopy is a reliable method for quantitative and qualitative analysis of minerals, while classifying rocks is more complex due to the optical behavior of the minerals that form the rock. Depending on the shape of the particles, aggregates can be rounded, irregular or partially rounded, angular or scaly. Approximation is analyzed in terms of its classification properties using Mahalanobis distance or flexible discriminant analysis. Common multivariate statistical methods used in chemometric studies, followed by linear discriminant analysis, do not always lead to acceptable classification error rates.
Knowing the different classifications of aggregates is a great starting point when planning a concrete construction project. Statistical classification of different petrographic varieties of aggregates using near and medium infrared spectra can be used to determine their origin. Rocks are generally classified as igneous, sedimentary, or metamorphic based on how they formed over long periods of geologic time. The geological formation of bedrock, weathering processes, petrological structure and texture all influence the physical properties of aggregates. As mentioned above, aggregates can be classified as natural or crushed based on their source and production technique.