Concept explainers
Videos
State whether the following are true or false.
a. In the AASHTO classification Table 4.1, the soils that are more suitable for roadwork are located on the left than right.
b. In AASHTO classification system, the better performing fine grained soils are the ones with lower group indices.
c. In AASHTO classification system, sands are classified as grains with 0.075-4.75 mm diameter.
d. The USCS symbol for clayey gravel is CG.
e. A soil with USCS symbol SM is sandy silt.
(a)
Find whether the statement is true or false.
Answer to Problem 4.1P
The statement, “In the AASHTO classification Table 4.1, the soils that are more suitable for roadwork are located on left than right” is true.
Explanation of Solution
Refer Table 4.1, “Classification of highway Subgrade Materials” in the textbook.
- Consider the Granular materials are listed left side in the table and Silt-clay materials are listed right side in the Table.
- The soil groups are classified by AASHTO system as A-1, A-2, A-3, A-4, A-5, A-6 and A-7.
- The group classification of the soil A-1 and A-2 belongs to left side of the table and A-4 to A-7 belongs to right side of the table.
- The general subgrade rating of the soil A-1 and A-2 has ‘excellent to good’.
- The general subgrade rating of the soil A-4 to A-7 has ‘fair to poor’.
Generally the rating from excellent to good subgrade materials are suitable for roadwork. So the classification of the soil A-1 and A-2 is used for roadwork, but the soil group A-4 to A-7 is not used for road work due to its poor rating.
Thus, the soils belongs to left side than the right side of the table is fit for roadwork.
Therefore, the statement, “In the AASHTO classification Table 4.1, the soils that are more suitable for roadwork are located on left than right” is true.
(b)
Find whether the statement is true or false.
Answer to Problem 4.1P
The statement, “In the AASHTO classification system, the better performing fine grained soils are the ones with lower group indices” is true.
Explanation of Solution
Refer Table 4.1, “Classification of highway Subgrade Materials” in the textbook.
- The AASHTO system classified the soil group as A-1, A-2, A-3, A-4, A-5, A-6 and A-7.
- The group classification of the soil A-1 and A-2 belongs to granular materials and the soil A-4 to A-7 belongs to Silt-clay materials
- From the sieve analysis the gravel, sand and fine sand are grouping under soil A1 and A2 and silty soils and clayey soils are grouping under A-4, A-5, A-6 and A-7.
- The soil group A-1 and A-2 is rated as ‘excellent to good’.so it is considered as better performing fine grained soils.
Thus, the better performing fine grained soils are the ones with lower group indices (A-1 and A-2).
Therefore, The statement, “In the AASHTO classification system, the better performing fine grained soils are the ones with lower group indices” is true.
(c)
Find whether the statement is true or false.
Answer to Problem 4.1P
The statement, “In the AASHTO classification system, sands are classified as grains with 0.075-4.75 mm diameter” is false.
Explanation of Solution
As per AASHTO system, the grain size from 2 mm to 0.075 mm is classified as sand.
As per USCS system, the grain size from 4.75 to 0.075 mm is classified as sand.
The sand is classified by USCS system, but in the given statement mentioned as AASHTO system. So the statement is wrong.
Therefore, The statement, “In the AASHTO classification system, sands are classified as grains with 0.075-4.75 mm diameter” is false.
(d)
Find whether the statement is true or false.
Answer to Problem 4.1P
The statement, “The USCS symbol for clayey gravel is CG” is false.
Explanation of Solution
Refer to Figure 4.3, “Flowchart group names for gravelly and sandy soil”
The group symbol ‘GC’ represents the group name as ‘clayey gravel’ and ‘clayey gravel with sand’.
As per USCS system, the correct group symbol for clayey soil is GC. Hence the given statement is wrong.
Therefore, The statement, “The USCS symbol for clayey gravel is CG” is false.
(e)
Find whether the statement is true or false.
Answer to Problem 4.1P
The statement, “A soil with USCS symbol SM is sandy silt” is false.
Explanation of Solution
Refer to Figure 4.3, “Flowchart group names for gravelly and sandy soil”
The group symbol ‘SM’ is represents the group name as ‘silty sand’ and ‘silty sand with gravel’.
As per USCS system, the correct group name for the symbol SM is silty sand and silty sand with gravel, but in the given statement it is mentioned as sandy silt. Hence, the given statement is wrong.
Therefore, the statement, “A soil with USCS symbol SM is sandy silt” is false.
Want to see more full solutions like this?
Chapter 4 Solutions
Fundamentals of Geotechnical Engineering (MindTap Course List)
- In AASHTO, which group are the following soil likely to fail into? a. A well-graded gravel with approximately 10% fines b. A well-graded sand with approximately 10% fines c. A uniform fine sand d. A high plastic clayarrow_forwardQuestion 4 Classify the following soils using the Unified soil classification system. Give group symbols and group names. % Passing No. 4: 99 % Passing No. 200: 76 LL = 60 PL = 32 %3D Group Symbol: Blank 1 Group name: Blank 2 Blank 1 Add your answer Blank 2 Add your answerarrow_forwardQuestion 3 The sieve analysis of soil and the liquid and plastic limits of the fraction passing through the No. 40 sieve are given below. Classify the soils using the AASHTO classification system and give the group indexes. % Passing No. 10: 48 % Passing No. 40: 28 % Passing No. 200: 6 LL = - %3D PL = NP Group classification: Blank 1 Group index: Blank 2arrow_forward
- A fine-grained soil (no sand) is found to have a liquid limit of 70 percent and a plastic limit of 38 percent. (a) What do the percentages for these limit values represent? (b) What is the plasticity index for this soil? (c) On the plasticity chart for the Unified Soil Classification System, what soil type is this? (d) On the plasticity chart for the AASHTO classification system, what soil type is this?arrow_forward1. Why will bulk density vary between soils but it is valid to use a constant value for particle density (2.65 g cm-3)?arrow_forwardFrom a particle size distribution curve of a sandy soil the following were obtain: Size of particle 0.48 mm percentage finer 60;Size of particle 0.33 mm percentage finer 30,Size of particle 0.21 mm percentage finer 10;Size of particle 0.11 mm percentage finer 5. Classify the soil using USCS. Justify your answer. Oa, SP O b. SM O c. SC O d. SWarrow_forward
- 1. Classify the following soils by using the USDA's textural classification chart. Soil Particle-size Distribution (%) A B C D E Soil A B C DE 2. Classify the foloowing soils according to the AASHTO classification system and give the group indices. Liquid Limit A B C D E Gravel 0 0 10 20 15 No. 10 92 90 100 72 100 No. 4 100 88 72 89 71 Sieve Analysis, % Finer No. 40 Sand 25 5 20 40 32 % Finer 81 70 92 61 85 No. 200 64 26 34 65 11 No. 200 52 34 78 33 71 Liquid Limit 28 38 29 44 32 Silt 65 7 35 22 25 Plastic Limit 10 20 14 23 16 29 37 61 35 55 3. Classify the following soils by using Unified Soil Classification System. Give the group symbols and the group names. Soil Uniformity Coefficient ---- ---- Clay 10 88 30 18 28 ---- 4.8 Plasstic Limit 16 3222 30 26 21 Coefficient of Gradation ---- ---- ---- ---- 2.9arrow_forward2. The following table shows results of testing of two types of soil: Soil G, W% S, LL PL A. 2.22 25 0.95 0.35 22 В 2.72 38 1.01 0.62 26 C 2.66 45 0.92 0.80 35 Answer the question below: I. Which of these soils contains less clay particles? Note ** show in solution process answers II. Which of these soils has a less void ratio? Note ** show in solution process answers III. Which of these soils has a less dry density? Note ** show in solution process answersarrow_forward2. Prove n-e/(1+e) and e-n/(1-n) based on definitions of void ratio and porosity. 3. Classify the following soils according to the unified soil classification system: group symbols and typical names Soil A B Percent passing U.S. sieve No. 4 No. 10 No. 20 No. 40 No. 60 No. 100 No. 200 95 86 65 52 46 38 25 98 95 88 82 75 65 100 LL PL 38 65 22 58arrow_forward
- The sieve analysis of ten soils and the liquid and plastic limits of the fraction passing through the No. 40 sieve are given below. Classify the soils using the AASHTO classification system and give the group indexes. % Passing No. 10: 100 % Passing No. 40: 78 % Passing No. 200: 8 LL = - PL NP (Non-Plastic) Group classification: Blank 1 Group index: Blank 2 Blank 1 Add your answer Blank 2 Add your answerarrow_forwardThe sieve analysis of ten soils and the liquid and plastic limits of the fraction passing through the No. 40 sieve are given below. Classify the soils using the AASHTO classification system and give the group indexes. % Passing No. 10: 92 % Passing No. 40: 75 % Passing No. 200: 62 LL = 43 PL = 28 Group classification: Blank 1 Group index: Blank 2 Blank 1 Add your answer Blank 2 Add your answerarrow_forwardThe properties of seven different clayey soils are shown below. Investigate the relationship between the strength and plasticity characteristics by performing the following tasks: Soil Beauharnois Detroit I Horten Gosport Mexico City Shellhaven St. Thuribe Mineral % Clay fraction (<2 μm) Kaolinite Illite 79 36 40 55 90 41 36 Montmorillonite Halloysite (hydrated) Halloysite (dehydrated) Attapulgite Allophane Activity, A 0.52 0.36 0.42 0.89 4.5 1.33 0.33 Liquid limit, LL 35-100 60-120 100-900 Undisturbed shear strength (kN/m²) 50-70 40-55 150-250 200-250 18 17 41 29 46 36 38 a. Estimate the plasticity index for each soil using Skempton's definition of activity. b. Estimate the probable mineral composition of the clay soils based on plasticity index and activity using the table below. Plastic limit, PL 20-40 35-60 50-100 Sensitivity, S, 14 40-60 30-45 100-125 120-150 2.5 17 2.2 5.3 7.6 150 Activity, A 0.3-0.5 0.5-1.2 1.5-7.0 0.1-0.2 0.4-0.6 0.4-1.3 0.4-1.3 c. Sensitivity refers to the…arrow_forward
Fundamentals of Geotechnical Engineering (MindTap...Civil EngineeringISBN:9781305635180Author:Braja M. Das, Nagaratnam SivakuganPublisher:Cengage Learning
Principles of Geotechnical Engineering (MindTap C...Civil EngineeringISBN:9781305970939Author:Braja M. Das, Khaled SobhanPublisher:Cengage Learning
Principles of Foundation Engineering (MindTap Cou...Civil EngineeringISBN:9781337705028Author:Braja M. Das, Nagaratnam SivakuganPublisher:Cengage Learning