and permeability. With careful selection of the gradation, it is possible to achieve high bulk density, high physical stability, and low permeability. This is important because in pavement design, a workable, stable mix with resistance to water is important. With an open gradation, the bulk density is relatively low, due to the lack of fine particles, the physical stability is moderate, and the permeability is quite high. With a rich gradation, the bulk density will also be low, the physical stability is low, and the permeability is also low. The gradation can be affected to achieve the desired properties for the particular engineering application. Engineering applications Gradation is usually specified for each engineering application it is used for. For example, foundations might only call for coarse aggregates, and therefore an open gradation is needed. Sieve analysis determines the particle size distribution of a given soil sample and hence helps in easy identification of a soil's mechanical properties. These mechanical properties determine whether a given soil can support the proposed engineering structure. It also helps determine what modifications can be applied to the soil and the best way to achieve maximum soil strength. See also Soil gradation Automated sieving using photoanalysis Optical granulometry References External links List of ASTM test methods for sieve analysis of various materials ASTM C136 / C136M - 14 Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates ASTM B214 - 16 Standard Test Method for Sieve Analysis of Metal Powders Chemical engineering Soil Classification System, Unified Granulometric analyses Particle technology