Test 3 - Soil Classification and Identification

Question 1 ప్రశ్న 1

According to IS 1498, which criterion distinguishes a coarse-grained soil from a fine-grained soil in laboratory classification?

A More than 50% of the soil must be retained on the 4.75 mm IS sieve to qualify as coarse-grained. B More than 50% of the total soil material by dry mass must be coarser than the 75-micron IS sieve size for the soil to be coarse-grained. C Every soil containing clay minerals must be classified as fine-grained irrespective of particle proportions. D A soil is coarse-grained only when its coefficient of uniformity exceeds six.

Question 2 ప్రశ్న 2

Which particle-size boundaries are consistent with IS 1498 for the gravel and sand components of soil?

A Gravel: 2–60 mm; sand: 0.002–2 mm. B Gravel: 4.75–80 mm; sand: 0.002–4.75 mm. C Gravel: 75 microns–4.75 mm; sand: 4.75–75 mm. D Gravel: 4.75–75 mm; sand: 75 microns–4.75 mm.

Question 3 ప్రశ్న 3

An engineer finds that most particles in a fine soil are smaller than 2 microns. Which statement is most accurate under the IS 1498 engineering-classification framework?

A The particles may be described as clay-size, but the engineering classification as clay or silt also requires consideration of plasticity and related behaviour. B The soil must be assigned group symbol CH regardless of liquid limit or plasticity index. C Every particle smaller than 2 microns is necessarily an expansive clay mineral. D The soil must be classified as gravel if its dry strength is high.

Question 4 ప్రశ్న 4

A soil sample has 62% of its dry mass passing the 75-micron IS sieve. What is its primary classification division under IS 1498?

A Coarse-grained gravel because some particles are retained on the sieve. B Coarse-grained sand because the percentage passing exceeds 50%. C Fine-grained soil because more than half its mass is finer than 75 microns. D Highly organic soil because more than half the particles pass the sieve.

Question 5 ప్రశ్న 5

A soil contains 38% gravel-size particles, 30% sand-size particles and 32% fines by dry mass. Under IS 1498, how should its primary division and coarse-grained subdivision be identified?

A Fine-grained soil because the fines percentage exceeds 30%. B Coarse-grained gravel because 68% is coarser than 75 microns and gravel predominates within that coarse fraction. C Coarse-grained sand because sand forms 30% of the total mass. D Fine-grained clay because the combined sand and fines percentage is 62%.

Question 6 ప్రశ్న 6

A soil contains 12% gravel, 56% sand and 32% fines by dry mass. According to IS 1498, which statement correctly identifies its primary coarse-grained subdivision?

A It is coarse-grained sand because the coarse fraction is 68% and sand is its dominant component. B It is fine-grained soil because the fines content exceeds 12%. C It is coarse-grained gravel because gravel is retained on the 4.75 mm sieve. D It must be classified as well-graded sand because sand exceeds 50% of the sample.

Question 7 ప్రశ్న 7

Which treatment of fines content in coarse-grained soils agrees with the laboratory-classification rules of IS 1498?

A All coarse-grained soils containing any fines must be classified only as GM or SM. B The threshold separating clean and fines-bearing coarse soils is always exactly 25%. C Coarse-grained soils containing 5–12% fines must be classified only as clean GW or SW. D Less than 5% fines generally permits clean-soil symbols, more than 12% requires classification according to the fines, and 5–12% is a borderline range requiring dual symbols.

Question 8 ప్రశ్న 8

A 1000 g dry soil sample contains 150 g gravel, 650 g sand and 200 g fines. The fines are non-plastic, and their behaviour is consistent with silt. What is the correct IS 1498 group symbol?

A GW. B SC. C SM. D ML.

Question 9 ప్రశ్న 9

For a soil grain-size distribution, D10 = 0.15 mm and D60 = 1.50 mm. What is the coefficient of uniformity Cu?

A 0.10. B 10.0. C 1.35. D 100.0.

Question 10 ప్రశ్న 10

A soil has D10 = 0.20 mm, D30 = 0.60 mm and D60 = 2.00 mm. What is its coefficient of curvature Cc?

A 0.90. B 1.50. C 3.00. D 10.00.

Question 11 ప్రశ్న 11

A clean gravel containing 3% fines has Cu = 5.0 and Cc = 2.0. Assume gravel predominates over sand in the coarse fraction. What is its group symbol under IS 1498?

A GP. B GM. C SW. D GW.

Question 12 ప్రశ్న 12

A clean sand contains 2% fines and has Cu = 8.0 and Cc = 0.60. Which IS 1498 group symbol is appropriate?

A SW. B SM. C SP. D SC.

Question 13 ప్రశ్న 13

A sand-dominated coarse-grained soil contains 20% fines. The fines have plasticity index 3 and show silt-like behaviour. Which group symbol is most appropriate under IS 1498?

A SW. B SM. C SC. D CH.

Question 14 ప్రశ్న 14

A soil contains 60% gravel, 25% sand and 15% fines. Its fines have liquid limit 42% and plasticity index 22. Using the A-line Ip = 0.73(wL - 20), which group symbol is appropriate?

A GC. B GM. C GW. D SC.

Question 15 ప్రశ్న 15

A sand-dominated coarse-grained soil contains 8% non-plastic fines. Its gradation parameters are Cu = 8.0 and Cc = 1.5. Which IS 1498 classification is most suitable?

A SP only. B SC only. C ML only. D SW-SM.

Question 16 ప్రశ్న 16

A soil has 65% by mass passing the 75-micron sieve. It is inorganic, with liquid limit 42% and plasticity index 19. What is its IS 1498 group symbol?

A CL. B MI. C CI. D CH.

Question 17 ప్రశ్న 17

An inorganic fine-grained soil has liquid limit 30% and plasticity index 2. What is its IS 1498 classification, assuming it is not a borderline organic soil?

A CL. B ML. C MI. D CH.

Question 18 ప్రశ్న 18

An inorganic fine-grained soil has liquid limit 60% and plasticity index 35. Which IS 1498 group symbol applies?

A CH. B MH. C CI. D CL.

Question 19 ప్రశ్న 19

A fine-grained inorganic soil has liquid limit 65% and plasticity index 10. Which classification is appropriate under IS 1498?

A CH. B CI. C ML. D MH.

Question 20 ప్రశ్న 20

For a soil with liquid limit 45%, the A-line is defined as Ip = 0.73(wL - 20). If its measured plasticity index is 21, which statement is correct?

A The A-line ordinate is 32.85, and the soil plots below it. B The A-line ordinate is 21.00, and the soil lies exactly on it. C The A-line ordinate is 18.25, and the soil plots above it. D The A-line ordinate is 7.30, and the soil lies within the 4–7 borderline zone.

Question 21 ప్రశ్న 21

A fine-grained soil has a liquid limit of 40% before oven drying and 24% after oven drying and remixing with water. Under the organic-soil identification criterion of IS 1498, what is the appropriate interpretation?

A The soil is certainly inorganic because its liquid limit decreases after drying. B The ratio is 0.60, below 0.75, which provides positive identification of organic soil under the stated criterion. C The ratio is 1.67, which automatically classifies the soil as CH. D The soil must be classified as peat solely because its initial liquid limit is 40%.

Question 22 ప్రశ్న 22

During field identification, a moist fine-grained soil pat shows rapid dilatancy when shaken, little dry strength and negligible toughness near its plastic limit. Which interpretation is most defensible?

A The observations are characteristic of silt-like, low-plasticity behaviour, subject to confirmation by laboratory classification tests. B The soil must be high-plasticity clay because rapid dilatancy always indicates high cohesion. C The soil must be gravel because dry strength is low. D The soil must be highly organic peat regardless of its colour, texture or organic content.

Question 23 ప్రశ్న 23

Which statement correctly describes the purpose and physical basis of hydrometer analysis in soil particle-size determination?

A It determines gravel size by measuring particles retained on a 75 mm sieve. B It determines soil plasticity index directly from the time required for a liquid-limit groove to close. C It measures the dry unit weight of coarse aggregates by applying an impact load. D It estimates the distribution of fine particle sizes from changes in suspension density during settling, using principles based on Stokes' law under suitable assumptions.

Question 24 ప్రశ్న 24

A dry soil sample weighs 500 g and contains 45 g gravel, 280 g sand and 175 g fines. The fines are non-plastic and exhibit silt-like behaviour. Which group symbol follows from the IS 1498 coarse/fine division and fines criteria?

A ML. B SC. C SM. D SW.

Question 25 ప్రశ్న 25

A soil investigation report provides an IS 1498 group symbol obtained from sieve analysis and Atterberg limits. Which additional information is most important for a reliable engineering description of the actual foundation stratum?

A In-situ density or consistency, moisture, stratification, cementation, drainage conditions and other relevant field observations in addition to the laboratory group symbol. B Only the colour of the soil on an oven-dried sample, because the group symbol determines all other properties. C Only the coefficient of uniformity, because it establishes the in-situ bearing capacity uniquely. D No further information, because soils having the same classification symbol necessarily have identical engineering strength and settlement.

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