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Highway Engineering Multiple Choice Questions on “Stone aggregates – 1”.
1. If the load value at 2.5mm penetration in CBR is 190kg and the load for 5.0mm penetration is 48kg, then the CBR value at 5 mm penetration is?
a) 4.6
b) 4.4
c) 4.3
d) 4.1
Answer: b
Clarification: CBR value at 5.0mm penetration=48*190/2055
=4.4%
2. The plate bearing test is used to evaluate __________
a) Modulus of sub grade reaction
b) Modulus of sub base reaction
c) Modulus of base reaction
d) Modulus of pavement
Answer: a
Clarification: The plate bearing test is used to evaluate the modulus of subgrade reaction “k” which is used in westergards analysis.
3. If the shear strength of the non-cohesive soil is 84KN/m2 and angle of friction is 30 degrees, then the normal strength in KN/m2 is?
a) 140
b) 141
c) 143
d) 145
Answer: d
Clarification:
S=c+σtanθ
84=σtan30
σ=145
4. Stone aggregate do not have to resist __________
a) Weathering effect
b) Traffic load
c) Wheel load stress
d) Soil load
Answer: d
Clarification: Stone aggregate do not have to resist the soil load as they are transferred by foundation only, weathering traffic and wheel load are directly experienced by aggregates.
5. Sand obtained from river is used as __________
a) Course aggregate
b) Fine aggregate
c) Filling materials
d) Substitute
Answer: b
Clarification: Sand obtained from river is used as fine aggregate as it can be used to fill the voids in the concrete, coarse aggregate is obtained from the rock, sand is not used as filling material but stone dust can be used if sand is not available.
6. Soft aggregates are used in __________
a) Lower layers
b) Upper layers
c) Everywhere in the pavement
d) Depends on the material
Answer: a
Clarification: Soft aggregates cannot resist the weathering action and wheel load of the vehicle, so they are preferred in lower layers, as they are impacted directly.
7. Which of the following is a soft aggregate?
a) Brick
b) Gravel
c) Clay
d) Silt
Answer: a
Clarification: Bricks are not actually aggregates, but the crushed bricks or over burnt bricks are used as aggregates in pavement they are not so hard as the hard aggregate.
8. Impact value is used to measure?
a) Hardness
b) Toughness
c) Wheel load
d) Strength
Answer: b
Clarification: The impact value of an aggregate is used to measure its toughness; if it is tough then it has a low impact value, hardness is for resistance to abrasion, strength is resistance to crushing.
9. The capability of aggregate to resist more weathering action and wheel load is called __________
a) Hardness
b) Toughness
c) Durability
d) Angularity
Answer: c
Clarification: Durability is the period till which the aggregate can resist the weathering action and other loads, hardness is the resistance to abrasion and toughness is the resistance to impact.
10. If the aggregates are exceptionally strong then they are having impact value which is?
a) Less than 10
b) Less than 15
c) Less than 30
d) Greater than 30
Answer: a
Clarification: The aggregates which have a less impact value are exceptionally tough, but normally the aggregate upto 30% impact value can be used.
11. The skid number for highways should not be less than __________
a) 55
b) 45
c) 35
d) 25
Answer: a
Clarification: The skid number for highways should not be less than 55 for national highways to ensure smooth ride, if it is less than 55 then suitable precautions have to be taken.
12. The specific gravity for aggregates should be within the range of __________
a) 2.5-2.8
b) 2.6-2.9
c) 2.4-2.6
d) 2.2-2.6
Answer: b
Clarification: The specific gravity for aggregates should be within the range of 2.6-2.9 for pavement construction purposes.
13. The crushing value of the aggregate determines its __________
a) Hardness
b) Strength
c) Toughness
d) Durability
Answer: b
Clarification: The resistance to crushing is referred as strength, whereas the resistance to abrasion is called hardness.
14. The flakiness index for surface dressing should not exceed __________
a) 15%
b) 25%
c) 35%
d) 45%
Answer: b
Clarification: The flakiness index for aggregates that are used in the pavement surface dressing should not exceed 25%, but in any case combined flakiness and elongation index should never exceed 30%.
15. The sum of flakiness index and elongation index should not exceed __________
a) 15
b) 20
c) 30
d) 40
Answer: c
Clarification: IRC recommends the combined flakiness and elongation index not to exceed 30%. for the aggregate that should be used in a highway.