A value of Cu greater than 4 to 6 classifies the soil as well graded. If the soil has 5–12% by weight of fines passing a #200 sieve (5% < P #200 < 12%), both grain size distribution and plasticity have a significant effect on the engineering properties of the soil, and dual notation may be used for the group symbol. Sand with particles of approximately the same size, for example, would be considered poorly graded sand with the classification SP. A - a poorly-graded medium SAND (probably estuarine or flood-plain alluvium) B - a well-graded GRAVEL-SAND (i.e. For example, GW-GM corresponds to "well-graded gravel with silt.". Inorganic soils with liquid limits below 50 that plot below the A-line are silt and are designated ML; those with liquid limits above 50 that plot below the A-line are elastic silts and are designated MH.The plasticity chart has a shaded area; soils that plot in this area (above the A-line with PI values between 4 and 7) are silty clay and are given the dual symbol CL-ML. The permeability of these soils is largely determined by the . This image below will probably explain everything much better than words can do. You figure out if the soil is well graded or not by the Coefficient of uniformity (C u) and the Coefficient of Curvature (C c ). Soil is graded as either well graded or poorly graded.The process for grading a soil is in accordance with either the Soil gradation is a classification of the particle size distribution of a soil. A gradation that, when plotted on the 0.45 power gradation graph, falls mostly below the 0.45 power maximum density line. For sands and gravels where more than 12% of the total sample passes the No. Uniformity Coefficient (Cu) The uniformity coefficient (Cu) is defined as the ratio of D60 to D10. These are the geometric properties of a grading curve that describe a particular type of soil.A grade size distribution curve is analyzed by using different particle sizes: D60, D30, and D10. Both of these criteria must be met for the soil to be SW, otherwise the classification is poorly graded sand (SP). FIG. If the soil under consideration is the fines component of a dual classified sand or gravel, the soil is classified as SM-SC or GM-GC.

The first symbol is always based on The U-line is not used in Unified Soil Classification System but is an upper boundary of expected results for natural soils. poorly graded (uniform particle sizes) W well-graded (diversified particle sizes) H high plasticity: L low plasticity If the soil has 5–12% by weight of fines passing a #200 sieve (5% < P #200 < 12%), both grain size distribution and plasticity have a significant effect on the engineering properties of the soil, and dual notation may be used for the group symbol.

A grading curve is a useful aid to soil description. 200 sieve then there is 60% passing the No. For example, poorly graded sand is designated SP and low plasticity clay is CL. A poorly graded soil will have better drainage than a well graded soil because there are more void spaces in a poorly graded soil.

200 sieve) are classified as well-graded gravel (GW) if Cu ≥ 4 and 1 £ Cc £ 3. for 1+3, enter 4. Soils with sufficient organic contents to influence properties that have liquid limits below 50 are classified as OL; those with liquid limits above 50 are classified as OH. To. Poorly Graded (P) Well Graded (W) Gap Graded Gap Graded Figure 2-3. from FHWA NHI-06-088. These coefficients help to classify the soil as well as graded or poorly graded ones.The uniformity coefficient (Cu) is defined as the ratio of D60 to D10. When Cu is less than 4, it is classified as poorly graded or uniformly graded soil.Uniformly graded soil has identical particles with Cu value approximately equal to 1. A uniformity coefficient value of 2 or 3 classifies the soil as poorly graded. Solve this simple math problem and enter the result. The grain diameter can be found for each percent of the soil passing a particular sieve. 200 sieve, both the gradation and plasticity characteristics must be evaluated and the soil is given a dual classification such as SP-SM, SP-SC, GW-GC, etc. 200 sieve, the soil is a clayey sand (SC), clayey gravel (GC), silty sand (SM), or silty gravel (GM).The second letter is assigned based on whether the fines classify as clay (C) or silt (M) as described for fine-grained soils below.