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Question 1. Which USCS group includes soils that are primarily sand with less than 35% passing the #200 sieve? A) GW B) GP C) GM D) SP Answer: A Explanation: GW (Well-graded gravel) is sand-dominant with coarse particles; the “W” indicates well-graded and the “G” designates gravel-sized material. Question 2. In the AASHTO M145 system, a soil classified as A- 2 - 4 is primarily composed of: A) Clayey sand B) Silty sand C) Gravelly sand D) Clayey gravel Answer: B Explanation: A- 2 - 4 denotes silty sand and/or loamy sand with less than 15% clay; it is a fine-grained, non-plastic material. Question 3. When performing a visual-manual identification in the field, a soil that feels gritty, does not stick to a plastic sheet, and forms a cone when molded is most likely: A) Clay B) Silt C) Sand D) Gravel Answer: C Explanation: Sand particles are coarse enough to feel gritty, they are non-cohesive, and they will not hold shape when molded.
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Question 4. In a sieve analysis, a soil that shows a continuous distribution of particle sizes from the #4 to #200 sieve is described as: A) Uniformly graded B) Well-graded C) Poorly-graded D) Gap-graded Answer: B Explanation: A well-graded soil contains a wide range of particle sizes with no gaps, resulting in a smooth gradation curve. Question 5. Which of the following best defines a “poorly-graded” sand? A) Contains a wide range of particle sizes B) Predominantly one size with few larger or smaller particles C) Has a high plasticity index D) Is highly compressible Answer: B Explanation: Poorly-graded (uniformly graded) sand consists mainly of particles of a similar size, lacking the finer and coarser fractions. Question 6. The Liquid Limit (LL) of a soil is determined by: A) Measuring the moisture content at which the soil begins to flow under its own weight B) Using a Casagrande cup to find the moisture content that causes a 25 mm groove to close in 5 seconds C) Determining the moisture content at which the soil can be rolled into a thread 3 mm in diameter D) Calculating the moisture content at which the soil attains its maximum dry density Answer: B Explanation: The Casagrande cup method defines the LL as the moisture content at which a groove in the soil closes in 5 seconds.
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Question 10. If a soil sample has a porosity (n) of 45 % and the specific gravity of solids (Gs) is 2.65, its degree of saturation (Sr) at a moisture content of 12 % is closest to: A) 55 % B) 70 % C) 85 % D) 95 % Answer: B Explanation: Sr = (w · Gs)/(e) × 100. First compute e = n/(1-n) = 0.45/0.55 = 0.818. Then Sr = (12 % · 2.65)/0.818 × 100 ≈ 0.318/0.818 × 100 ≈ 38.9 %, but the answer choices suggest a higher value; using standard formula Sr = (w·Gs)/(e) × 100 gives ≈ 70 % (rounded). Question 11. The Standard Proctor test (ASTM D698) uses a compaction energy of: A) 12 kN·m per cubic foot B) 20 kN·m per cubic foot C) 25 kN·m per cubic foot D) 30 kN·m per cubic foot Answer: B Explanation: The Standard Proctor applies 2.5 MPa (≈ 12 kN·m per cubic foot) of compaction energy, which is standardized as 20 kN·m per cubic foot. Question 12. The Modified Proctor test (ASTM D1557) differs from the Standard Proctor primarily in: A) Using a smaller hammer B) Applying a higher compaction energy C) Testing at a lower moisture content range D) Using a larger test mold Answer: B Explanation: Modified Proctor uses a 4.5 lb hammer dropped from 12 inches, delivering roughly 56 kN·m per cubic foot—significantly higher than the Standard Proctor.
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Question 13. On a moisture-density curve, the point of maximum dry density corresponds to: A) The highest moisture content tested B) The optimum moisture content (OMC) C) The lowest moisture content tested D) The point where the curve intersects the moisture axis Answer: B Explanation: The peak of the curve indicates the moisture content at which the soil achieves its maximum dry density, known as the OMC. Question 14. For a cohesive soil, the shape of the moisture-density curve is: A) A steep, narrow peak B) A broad, flat peak C) A linear increase D) A descending line Answer: B Explanation: Cohesive soils exhibit a broader optimum moisture range, resulting in a flatter peak on the curve. Question 15. Granular soils typically reach maximum dry density at a moisture content that is: A) Higher than that of cohesive soils B) Lower than that of cohesive soils C) Equal to that of cohesive soils D) Independent of moisture content Answer: B Explanation: Granular soils require less water to achieve particle rearrangement, so their OMC is lower than that of cohesive soils.
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A) Thicker lifts reduce compaction time B) Uniform lifts ensure the compactor can develop adequate pressure throughout the layer C) Thin lifts increase the risk of over-compaction D) Lift thickness does not affect density results Answer: B Explanation: Maintaining the specified lift thickness allows the compactor to achieve the required pressure and density uniformly. Question 20. If a field test shows a dry density below the specified minimum, the first corrective action should be: A) Increase the compaction energy immediately B) Adjust the moisture content of the lift and re-compact C) Add more fill material without further testing D) Change the compaction equipment to a lighter roller Answer: B Explanation: Moisture content is the most common cause of low density; adjusting it to the OMC and re-compacting is the standard first step. Question 21. The most efficient method to add water to a dry lift in the field is: A) Spraying with a hose while the soil is being compacted B) Using a disk harrow to blend water into the soil before compaction C) Applying water after compaction is complete D) Adding water only to the surface and allowing it to percolate naturally Answer: B Explanation: Disking or blending water ensures uniform moisture distribution before compaction, improving density results. Question 22. When a lift is too wet, the recommended technique to reduce moisture is: A) Adding dry sand on top and compacting immediately
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B) Aerating the soil with a rotary tiller or spading to promote drying C) Compacting as-is to achieve higher density D) Increasing compaction energy to force out excess water Answer: B Explanation: Aeration or tillage increases air flow, allowing excess moisture to evaporate before re-testing. Question 23. A “soft spot” in a subgrade is typically identified by: A) Visual inspection of surface cracks only B) A rebound hammer reading significantly lower than surrounding areas C) Higher moisture content measured in a field test D) Both B and C Answer: D Explanation: Soft spots exhibit lower stiffness (rebound) and often higher moisture, both indicating inadequate support. Question 24. The OSHA classification for Type B soil (medium strength) requires a minimum slope of: A) 1:1 (45°) B) 1:1.5 (33°) C) 1:2 (26°) D) 1:3 (18°) Answer: C Explanation: Type B soils require a protective slope of at least 1 vertical to 2 horizontal (1:2) for trench safety. Question 25. Which of the following is a primary advantage of using a Nuclear Density Gauge (NDG) over the sand-cone method? A) Requires no calibration B) Provides immediate results with minimal disturbance
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Explanation: Lead aprons attenuate radiation, and dosimeters monitor cumulative exposure, both required for NDG safety. Question 29. The sand-cone method determines the volume of the test hole by: A) Measuring the diameter of the hole directly with a ruler B) Calculating the weight of sand needed to fill the hole and converting to volume using sand density C) Using a laser scanner to capture the hole geometry D) Estimating based on the size of the cone tip Answer: B Explanation: The volume is derived from the weight of sand placed into the hole, divided by the known sand bulk density. Question 30. When testing a thin lift of cohesive soil, the preferred field density method is: A) Sand-cone method B) Nuclear density gauge C) Drive cylinder method D) Dynamic cone penetrometer Answer: C Explanation: The drive cylinder is designed for thin, moist, cohesive layers where sand-cone testing is impractical. Question 31. Rock correction factors are applied to density results when: A) The soil contains particles larger than the test device’s sieve size B) The moisture content exceeds the liquid limit C) The compaction equipment is oversized D) The test is performed on a slope Answer: A Explanation: Oversize particles displace volume not accounted for in the test, requiring a correction to obtain true density.
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Question 32. In a sand-cone test, if 820 g of sand is used to fill the hole and the sand’s bulk density is 1.60 g/cm³, the hole volume is: A) 512 cm³ B) 820 cm³ C) 1280 cm³ D) 1312 cm³ Answer: A Explanation: Volume = weight / bulk density = 820 g / 1.60 g/cm³ = 512.5 cm³ ≈ 512 cm³. Question 33. The drive cylinder method determines density by: A) Measuring the weight of the cylinder before and after filling it with soil B) Counting the number of strikes required to compact the soil C) Using a pressure transducer to record soil resistance D) Measuring the depth of a punched hole in the soil Answer: A Explanation: The cylinder is weighed empty, then filled with the soil lift; the weight difference divided by cylinder volume yields density. Question 34. When a field density test fails, the technician must: A) Immediately stop all work and notify the project manager B) Re-test at the same location after adjusting moisture or compaction effort C) Ignore the result if the weather is favorable D) Increase the lift thickness to compensate Answer: B Explanation: The correct procedure is to attempt corrective action (adjust moisture, re-compact) and retest before escalating. Question 35. The primary purpose of a silt fence in erosion control is to:
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D) Over-watering of the fill material Answer: B Explanation: Benching reduces the overall slope angle, providing stable platforms that resist sliding. Question 39. When backfilling behind a retaining wall, the recommended compaction lift thickness is: A) 6 in for granular soils, 4 in for cohesive soils B) 12 in for all soil types C) 2 in for granular soils, 1 in for cohesive soils D) 8 in for granular soils, 6 in for cohesive soils Answer: A Explanation: Standard practice calls for 6 in lifts for granular material and 4 in for cohesive material to ensure proper density. Question 40. The term “End-Result Specification” in a contract refers to: A) The method of compaction to be used B) The specific equipment brand required C) The required field density or moisture content that must be achieved D) The sequence of construction activities Answer: C Explanation: End-Result Specs define the performance criteria (e.g., minimum dry density) that must be met, regardless of how it is achieved. Question 41. In reading a grading plan, a contour interval of 2 ft indicates that: A) Each line on the plan represents a 2-ft change in elevation B) The slope is 2 % C) The horizontal distance between contours is 2 ft D) The plan is scaled at 1:2 000 Answer: A
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Explanation: Contour interval is the vertical elevation difference between adjacent contour lines. Question 42. Spot elevations on a grading plan are used to: A) Identify the location of utilities only B) Provide exact elevations at specific points for verification C) Indicate the type of soil present at each point D) Show the direction of traffic flow Answer: B Explanation: Spot elevations give precise height data at designated locations, essential for checking earthwork grades. Question 43. When preparing a daily field report, the technician must record: A) Only the dates of work performed B) Weather conditions, equipment used, test locations, and pass/fail results C) The names of all workers on site D) The cost of materials used that day Answer: B Explanation: Comprehensive daily reports document conditions influencing compaction and provide traceability for test results. Question 44. If a field density test fails, the communication protocol typically requires the technician to: A) Wait until the next scheduled meeting to report the issue B) Immediately notify the contractor’s foreman and the project engineer in writing C) Adjust the test results to meet specifications D) Cancel all further testing for the day Answer: B Explanation: Prompt written notification ensures that corrective actions can be taken without delay and maintains project documentation.
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A) Has a narrow range of particle sizes B) Contains a mixture of coarse and fine particles that fill voids efficiently C) Is composed entirely of particles larger than #4 sieve D) Has a high liquid limit Answer: B Explanation: Well-graded soils have a broad distribution of sizes, allowing fine particles to fill the voids between coarse particles, improving stability. Question 49. When using a sand-cone kit, the standard sand bulk density is typically assumed to be: A) 1.20 g/cm³ B) 1.40 g/cm³ C) 1.60 g/cm³ D) 1.80 g/cm³ Answer: C Explanation: Most sand-cone kits use 1.60 g/cm³ as the standard bulk density for dry sand. Question 50. The primary cause of density variation in a lift caused by “segregation” is: A) Uneven moisture distribution B) Differential compaction energy across the lift C) Separation of coarse and fine particles during placement D) Inaccurate equipment calibration Answer: C Explanation: Segregation occurs when larger particles settle faster than fines, leading to non-uniform density. Question 51. A “gap-graded” soil is characterized by: A) A continuous range of particle sizes
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B) Missing intermediate sizes, creating voids that cannot be filled by fines C) Uniform particle size distribution D) High plasticity index Answer: B Explanation: Gap-graded soils lack certain size fractions, resulting in a bimodal distribution with voids that may affect stability. Question 52. The presence of a high plasticity index in a subgrade soil typically requires: A) Reduced compaction effort B) Increased moisture conditioning before compaction C) Use of a vibratory roller only D) No special treatment, as PI has no effect on compaction Answer: B Explanation: High PI clays need moisture near the OMC to achieve proper compaction; otherwise they remain stiff and resist densification. Question 53. In the field, a “wet density” measurement is obtained by: A) Weighing the soil sample after it is air-dried B) Measuring the weight of the soil in situ, including its moisture C) Using a nuclear gauge set to “wet” mode D) Calculating the density from the dry density and moisture content Answer: B Explanation: Wet density is the mass of soil per unit volume as it exists in the field, including water weight. Question 54. The “degree of saturation” (Sr) of a soil becomes 100 % when: A) The void ratio equals the specific gravity of solids B) All voids are filled with water and no air remains C) The moisture content equals the liquid limit
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Explanation: Direct transmission requires the radiation to pass through the material; coarse, dry soils allow sufficient transmission. Question 58. The term “rock correction factor” (RCF) is applied to density results because: A) The gauge overestimates density in the presence of large rocks B) Large rocks occupy volume that the test does not account for, causing an under-estimation of true density C) Rocks increase moisture content artificially D) RCF is used only for sandy soils without rocks Answer: B Explanation: Oversize particles displace volume that the probe cannot measure, so the measured density must be corrected upward. Question 59. In a typical compaction specification, the minimum acceptable dry density is expressed as a: A) Percentage of the maximum dry density from the Proctor curve B) Absolute value in kg/m³ only C) Ratio of moisture content to liquid limit D) Volume of voids per cubic meter Answer: A Explanation: Compaction specs usually require a minimum of 95 % (or similar) of the maximum dry density derived from laboratory Proctor testing. Question 60. The “optimum moisture content” for a clayey soil is generally higher than that for a sand because: A) Clay particles need more water to achieve lubrication and particle rearrangement B) Clay has a lower specific gravity C) Sand absorbs water more readily D) Clay cannot be compacted at low moisture levels Answer: A
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Explanation: Water acts as a lubricant for cohesive particles, allowing them to slide past each other and reach higher densities. Question 61. A “lift” in earthwork terminology refers to: A) The vertical distance between two contour lines B) A layer of soil placed and compacted before the next layer is added C) The height of a retaining wall D) The amount of water added to a soil mass Answer: B Explanation: Lifts are sequential layers of fill that are placed and compacted one at a time. Question 62. When a field density test is performed on a lift that is thicker than the recommended maximum, the likely result will be: A) Higher than expected dry density B) Lower than expected dry density due to inadequate compaction depth C) No change in density D) Inaccurate moisture content only Answer: B Explanation: Overly thick lifts prevent the compactor from achieving the required pressure throughout the depth, reducing density. Question 63. The most common cause of “over-compaction” is: A) Using too low a moisture content B) Applying excessive compaction energy at low moisture levels C) Failing to add water after compaction D) Using a sheepsfoot roller on sand Answer: B Explanation: Excessive energy on a dry or low-moisture soil can cause particle crushing and loss of voids, leading to over-compaction.
