Geotechnical · MCQ practice Compaction of Soil MCQs – Part 2
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Part 2 of 2 Question 1 Easy
The degree of compaction of a soil is characterised by its:
A consistency B compressibility C dry density D saturated unit weight
Answer: C. dry density
Degree (state) of compaction is measured by dry density: compaction increases the mass of solids per unit volume.
Question 2 Easy
Which type of rollers are most effective for the compaction of sands?
A Pneumatic rollers B Smooth wheeled rollers C Vibratory rollers D Sheep foot rollers
Answer: C. Vibratory rollers
Vibration rearranges cohesionless grains into a denser packing, so vibratory rollers are best for sands and gravels.
Question 3 Easy
Which of the following is NOT correct about the effects of compaction of soil?
A Compaction increases shear and bearing strength of soil B Compaction increases the permeability of soil C Compaction increases the frictional characteristics of soil D Compaction decreases the tendency for settlement of soil
Answer: B. Compaction increases the permeability of soil
Compaction reduces voids, so permeability decreases, not increases.
Question 4 Easy
For standard compaction test done on soil, the mass of hammer and drop of the hammer are:
A 4.80 kg and 310 mm B 2.60 kg and 450 mm C 5.40 kg and 450 mm D 2.60 kg and 310 mm
Answer: D. 2.60 kg and 310 mm
IS light (standard) compaction: 2.6 kg rammer, 310 mm free drop, 3 layers × 25 blows in a 1000 cm³ mould.
Question 5 Hard
The maximum dry density and optimum moisture content of a soil are 1.65 g/cc and 20.5% respectively. What is the percentage of air content of the soil at OMC, if the specific gravity of particles is 2.65?
A 10.4 B 15.5 C 26.8 D 35.7
Answer: A. 10.4
e = 2.65/1.65 − 1 = 0.606; S = wG/e = 0.205×2.65/0.606 = 0.896; air content = 1 − S ≈ 10.4%.
Question 6 Easy
Which of the following roller is used to compact the coarse-grained soil?
A Drum roller B Pneumatic tyred roller C Tamping roller D Vibratory roller
Answer: D. Vibratory roller
Coarse-grained (cohesionless) soils are compacted best by vibration, so a vibratory roller is used.
Question 7 Medium
Which of the following type of roller is most suitable for proof rolling subgrades and for finishing operation of fills with clayey or sandy soils?
A Pneumatic rubber tired roller B Sheepfoot roller C Smooth wheel roller D Vibratory roller
Answer: C. Smooth wheel roller
Smooth-wheeled rollers give a smooth, sealed finished surface and are used for proof rolling subgrades and finishing fills.
Question 8 Easy
When compaction effort is increased in the standard compaction test, the optimum moisture content:
A Decreases B Increases C Does not change D Is unpredictable
Answer: A. Decreases
More compactive effort shifts the curve up and left: MDD increases and OMC decreases.
Question 9 Easy
Optimum moisture content is obtained from?
A hydrometer test B standard proctor test C consolidation test D triaxial test
Answer: B. standard proctor test
OMC and MDD are found from the standard Proctor (compaction) test.
Question 10 Easy
Clayey soils are best compacted by:
A Sheep foot rollers B Vibratory rollers C Heavy drum rollers D Ramming and pneumatic tampering
Answer: A. Sheep foot rollers
Sheep-foot rollers knead and tamp clay, compacting it from the bottom of the layer upwards.
Question 11 Easy
During compaction the quantity of water at which the maximum density is obtained is known as:
A Half saturated soil B Water content C Saturated soil D Optimum moisture content
Answer: D. Optimum moisture content
The water content giving maximum dry density during compaction is the optimum moisture content (OMC).
Part 2 of 2