Classification of non-plastic soils

Abstract

Many types of soils exist in nature varying in their composition, size and characteristics. They have to be suitably classified before they are involved in any geotechnical application. However, clarity does not exist in the existing soil classification systems in classifying inorganic silts, silty sands and silty gravels that are non plastic. In order to make the unified soil classification system that is in wide usage more complete, additional group symbols are necessarily to be included that describe even the non-plastic soils also. This technical note proposes to include two new group symbols namely GMN (non-plastic silty gravels) and SMN (non-plastic silty sands) for coarse grained non-plastic soils and three more group symbols namely MLN (non-plastic, inorganic coarse silt sized fractions), MIN (non-plastic, inorganic medium silt sized fractions) and MHN (non-plastic, inorganic (fine silt + clay) sized fractions) to classify the fine grained, non-plastic silts, in the existing soil classification system.