For example, the Unified Soil Classification System, USCS, (ASTM D 2487), which is the most commonly used system in geotechnical work, is based on grain size, gradation, and plasticity. Each letter is described below (with the exception of Pt): It became known as the Unified Soil Classification System when several U.S. Government Agencies adopted a modified version of the Airfield System in 1952. However, it alone does not provide adequate descriptive terminology and … 14.330 SOIL MECHANICS Soil Classification Soil Type USCS Symbol Grain Size Range (mm) USCS AASHTO USDA MIT Gravel G 76.2 to 4.75 76.2 to 2 >2 >2 Sand S 4.75 to 0.075 2 to 0.075 2 to 0.05 2 to 0.06 Silt M Fines < 0.075 0.075 to 0.002 0.05 to 0.002 0.06 to 0.002 Clay C < 0.002 < 0.002 < 0.002 Determined by Mechanical Analysis (i.e. california department of transportation (cal trans) unified soil classification system unified soil classification and symbol chart laboratory Coarse Grained Run sieve analysis Gravel (G) Less than 5% pass No. view uscs-a11y.pdf from svc 001 at seneca college. It can With some modification it was jointly adopted by several U.S. government agencies in 1952. Additional refinements were made and it is currently standardized as ASTM D 2487-93. 1. It is used in the U.S. and much the Unified Soil Classification System, which is also briefly described below, to categorize soils accordingly to their engineering characteristics. For classification, a clay is a fine-grained soil, or the fine-grained portion of a soil, with a 2, for coarse-grained soils, can be used to assign the appropriate group symbol(s) and name. If the soil has properties which do not distinctly place it into a 1b for fine-grained soils, and Fig. Is soil highly organic, coarse grained, or fine grained? Guide to Pronouncing Taxonomic Terms Keys to Soil Taxonomy- taxonomic keys for field classification. Spanish Edition 3. ABBREVIATED NAME. Unified Soil Classification System (USCS), and the United States Department of Agriculture (USDA) soil classification system. Coarse grained Soils2. A geotechnical engineering soil classification example using the Unified Soil Classification System (USCS). 6.2 Soil Sampling 6.2.1 Selection of Sampling Equipment 6.2.2 Equipment Preparation 6.2.3 Soil Logs 6.2.3.1 Wentworth Scale Table 6.1 Wentworth Scale as Modified from Driscoll, 1986, and Folk, 1975. Although earth materials may be soil, rock, or combi-nations of soil and rock, this chapter focuses focus on soil materials. UNIFIED SOIL CLASSIFICATION . USDA Soil Classification Example Based on the sieve analysis of a granular backfill soil, the following percentages of aggregate sizes were identified from the gradation chart. UNIFIED SOIL CLASSIFICATION SYSTEM Name Group Symbols LABORATORY CRITERIA Fines (%) Grading Plasticity Notes coarse grained (more than 50% larger than 63 μm BS or No.200 US sieve size (0.074 mm)) Gravels (more than 50% of coarse fraction of gravel size) Well graded gravels, with little or no fines GW 0-5 C u >4 1