Classification of Soil

According to the U.S. Department of Agriculture (USDA) textural classification system, what are the particle size limits for silt?

A soil's particle-size distribution consists of 20 percent gravel, 10 percent sand, 30 percent silt, and 40 percent clay. To use the USDA textural classification chart, what is the modified percentage of clay?

What is a primary inadequacy of textural classification systems for most engineering purposes?

Under the AASHTO classification system, what is the defining characteristic that separates granular materials (groups A-1, A-2, A-3) from silt-clay materials (groups A-4, A-5, A-6, A-7)?

In the AASHTO classification system, when is the term 'clayey' applied to the fine fractions of a soil?

What is the formula for the Group Index (GI) used in the AASHTO classification system for soils in groups A-4, A-5, A-6, and A-7?

When calculating the Group Index (GI) for a soil, if the formula yields a value of 3.5, what value should be reported?

A soil has 58 percent passing the No. 200 sieve, a liquid limit of 30, and a plasticity index of 10. According to the AASHTO system, what is its classification?

For a soil classified as A-7-6 under the AASHTO system, what is the relationship between its Plasticity Index (PI) and Liquid Limit (LL)?

A soil has 34 percent passing the No. 200 sieve, a liquid limit of 37, and a plasticity index of 12. Using the AASHTO system, calculate its Group Index (GI).

The Unified Soil Classification System (USCS) classifies soils into how many broad categories based on the percentage passing the No. 200 sieve?

In the USCS, what does the symbol 'Pt' represent?

For a coarse-grained soil to be classified as a gravel (G) under the USCS, what condition must be met?

What are the criteria for a sand to be classified as well-graded (SW) in the USCS, assuming it has less than 5 percent fines?

Under the USCS, when is a dual symbol such as GC-GM or SC-SM required for a coarse-grained soil?

A fine-grained soil has a liquid limit of 50 or more. Under what condition is it classified as organic (OH) in the USCS?

What is a major difference in the classification of organic soils between the AASHTO and Unified systems?

A soil has a liquid limit of 30 and a plastic limit of 22. What is its plasticity index (PI), and where does it plot relative to the A-line on the plasticity chart?

A soil has 8 percent of its particles passing the No. 200 sieve. From its grain-size distribution curve, D10 = 0.085 mm, D30 = 0.12 mm, and D60 = 0.135 mm. What is its uniformity coefficient (Cu)?

A grain-size analysis shows that 61 percent of a soil passes the No. 200 sieve. Its liquid limit is 26 and its plastic limit is 20. According to the USCS, what is its group symbol?

A soil has 30 percent passing the No. 200 sieve, and 70 percent passing the No. 4 sieve. The coarse fraction is the material retained on the No. 200 sieve (70 percent). What percentage of the coarse fraction passes the No. 4 sieve?

A coarse-grained soil has 30 percent passing the No. 200 sieve, LL = 33, and PI = 21. More than 50 percent of its coarse fraction is sand. What is its USCS group symbol?

Which soil classification system is generally preferred by geotechnical engineers, as mentioned in the text?

What is the primary difference in the threshold for what is considered a fine-grained soil between the AASHTO and Unified systems?

According to the comparison tables, what is the most probable USCS classification for a soil classified as A-1-a in the AASHTO system?

According to the comparison tables, what is the most probable AASHTO classification for a soil classified as CH (inorganic clay of high plasticity) in the USCS?

For a soil classified as A-3 in the AASHTO system, what is the 'Usual types of significant constituent materials' according to Table 5.1?

A soil has a liquid limit of 60 and a plasticity index of 40. According to the plasticity chart for the USCS, how would this soil be broadly categorized if it were inorganic?

What is the general subgrade rating for soils classified in groups A-4, A-5, A-6, and A-7 in the AASHTO system?

In the context of the Unified Soil Classification System (USCS), what is the definition of the sand fraction?

A sandy soil in the USCS has 15 percent fines. The gravel content is greater than 15 percent. According to the group name conventions, what modifier should be added to its name?

For which AASHTO groups is the Group Index (GI) always 0?

What is the equation for the empirical A-line on the Casagrande plasticity chart?

A soil has a particle size distribution of 10 percent gravel, 20 percent sand, 41 percent silt, and 29 percent clay. Using the USDA system, what is its classification?

In the USCS, a soil with a liquid limit of 45 and a plasticity index of 15 is a fine-grained soil. What is its group symbol, assuming it is inorganic?

A soil is classified as A-1-b in the AASHTO system. According to the comparison tables, what are the MOST PROBABLE USCS classifications?

What does the symbol 'H' signify when used as a secondary letter in a USCS group symbol (e.g., CH, MH)?

Which AASHTO group represents clean, fine sand?

A soil classified as ML in the USCS would most probably be classified as which of the following in the AASHTO system?

A soil has more than 50 percent passing the No. 200 sieve. Its liquid limit is 28 and plasticity index is 5. It plots in the hatched area on the plasticity chart. According to the USCS, what is its classification?

What is the primary characteristic of the AASHTO group A-2?

An AASHTO A-7-6 soil has a liquid limit of 60. What can be inferred about its plasticity index (PI)?

A soil sample has 21 percent gravel, 12 percent sand, 35 percent silt, and 32 percent clay. Using the USDA system, what is its classification?

For a sandy soil with 5 to 12 percent fines in the USCS, what type of classification symbol is required?

Why does the text suggest the AASHTO system's 35 percent threshold for fine-grained soil might be more appropriate than the USCS's 50 percent threshold?

A fine-grained soil has a liquid limit of 65 and a PI of 25. According to the plasticity chart (Figure 5.3), how would it be classified under USCS if it is inorganic?

A soil sample consists of 18 percent sand, 24 percent silt, and 58 percent clay, with zero gravel. According to the USDA textural classification chart (Figure 5.1), what is its classification?

What is the Group Index (GI) of a soil classified as A-1-a in the AASHTO system?

An inorganic soil has the following properties: percent passing No. 4 sieve = 90; percent passing No. 200 sieve = 13; LL = 23; PL = 19. What is its classification under the Unified Soil Classification System?

A soil has a particle-size distribution of 12 percent gravel, 22 percent sand, 26 percent silt, and 40 percent clay. Using the USDA textural classification chart after modification, what is its classification?