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A poorly-graded soil is a soil that does not have a good representation of all sizes of particles from the no. 4 to no. 200 sieve. A poorly-graded gravel is classified as GP, while a poorly-graded sand is classified as SP. Poorly-graded soils are more susceptible to soil liquefaction than well-graded soils. [1]
Well-graded gravel Cu < 4 and/or Cc < 1 or Cc > 3 GP Poorly graded gravel Gravels with Fines. More than 12% fines Fines classify as ML or MH GM Silty Gravel Fines classify as CL or CH GC Clayey gravel Sands. 50% or more of coarse fraction passes No.4 sieve Clean Sands. Less than 5% fines Cu ≥ 6 and 1 ≤ Cc ≤ 3 SW Well-graded sand
A sieve analysis (or gradation test) is a practice or procedure used in geology, civil engineering, [1] and chemical engineering [2] to assess the particle size distribution (also called gradation) of a granular material by allowing the material to pass through a series of sieves of progressively smaller mesh size and weighing the amount of material that is stopped by each sieve as a fraction ...
If the soil particles in a sample are predominantly in a relatively narrow range of sizes, the sample is uniformly graded. If a soil sample has distinct gaps in the gradation curve, e.g., a mixture of gravel and fine sand, with no coarse sand, the sample may be gap graded. Uniformly graded and gap graded soils are both considered to be poorly ...
The original Proctor test, ASTM D698 / AASHTO T99, uses a 4-inch-diameter (100 mm) by 4.584-inch-high (116.4 mm) mold which holds 1/30 cubic feet of soil, and calls for compaction of three separate lifts of soil using 25 blows by a 5.5 lb hammer falling 12 inches, for a compactive effort of 12,375 ft-lbf/ft 3.
The liquid limit test is defined by ASTM standard test method D 4318. [4] The test method also allows running the test at one moisture content where 20 to 30 blows are required to close the groove; then a correction factor is applied to obtain the liquid limit from the moisture content. [5]
The USCS further subdivides the three major soil classes for clarification. It distinguishes sands from gravels by grain size, classifying some as "well-graded" and the rest as "poorly-graded". Silts and clays are distinguished by the soils' Atterberg limits, and thus the soils are separated into "high-plasticity" and "low-plasticity" soils ...
The test reports loss of mass to abrasion and impact, expressed as a percentage of initial sample mass. [7] Maximum acceptable loss for the base course of the road is 45%; the more demanding surface course must be 35% or less. [1] The test was developed by the city engineers of Los Angeles in the 1920s. [8]