Standard Practice for classification of soils and soil-aggregate mixtures for highway construction purposes practice covers a procedure for classifying mineral and organomineral soils into seven groups based on laboratory determination of particle-size distribution, liquid limit, an plasticity index. It may be used when precise engineering classification is required, especially for highway construction purposes. Evaluation of soils within each group is made bymeans of a group index, which is a value calculated from an empirical formula.
