To check the quality of the soil, a term group index is defined. A-8 includes Peat, muck, and other highly organic soils.Ī-1 soil is best to use as sub-grade then a-2 and so on. bearing capacity and serviceability characteristics are grouped together and classified into eight groups from A1 to A8Ī-1, A-2 and A-3 soils are coarse-grained soils While A-4, A-5, A-6 and A-7 represent the fine grained soils. Soils which have same general load carrying capacity i.e. This system of classification is based upon the observed field performance of soils under highway pavements (flexible and rigid) and is widely used around the world for highway and airfield construction. Introduction to AASHTO Classification System:
(a) Liquid limit and Plastic limit tests – Atterberg limit results Test Required for Classification of Soil according to AASHTOĪs we will be trying to classify the soil in the laboratory thus we will use results of some tests to classify the soil
In this post we will be classifying the soil according to AASHTO Soil classification system, USCS will be discussed in some other post in detail.
- AASHTO (American Association for State Highway and Transportation officials) soil classification system.
- USCS – Unified Soil Classification system – which is mostly used for buildings and for structures where soil will be used to support foundations or footings.
- Two of the most commonly used soil classification systems are