National Level Technical Quiz on RCC Structures

 

A National Level Technical Quiz on RCC Structures

To determine the modulus of rupture, the size of test specimen used is

100 x100 x700 mm

150 x150 x700 mm

150 x150 x500 mm

100 x100 x500 mm

Answer: 150 x150 x700 mm

 

The property of fresh concrete, in which the water in the mix tends to rise to the surface while placing and compacting, is called

Segregation

Bleeding

Bulking

Creep

Answer: Bleeding

 

The property of the ingredients to separate from each other while placing the concrete is called

Segregation

Bulking

Compaction

Shrinkage

Answer: Segregation

 

Workability of concrete is directly proportional to

Aggregate Cement ratio

Time of Transit

Grading of the aggregate

All of the above

Answer: Grading of the aggregate

 

Workability of concrete is inversely proportional to

Time of transit

Water Cement ratio

The air in the mix

Size of the aggregate

Answer: Time of transit

 

Approximate value of shrinkage strain in concrete, is

0.003

0.0003

0.00003

0.03

Answer: 0.0003

 

Air entrainment in the concrete increases

Workability

Strength

The effects temperature variations

The unit weight

Answer: Workability

 

Strength of concrete increases with

Increase in water-cement ratio

Increase in fineness of cement

Decrease in curing time

Decrease in size of aggregate

Answer: Increase in fineness of cement

 

The compressive strength of 100 mm cube as compared to 150 mm cube is always

Less

More

Equal

None of the above

Answer: More

 

Increase in the moisture content in concrete

Reduces the strength

Increases the strength

Does not change the strength

All of the above

Answer: Reduces the strength

 

compared to ordinary portland cement, use of puzolonic cement

Reduces workability

Increases bleeding

Increases shrinkage

Increases strength

Answer: Increases shrinkage

 

Admixtures which cause early setting, and hardening of concrete are called

Workability admixtures

Accelerators

Retarders

Air entraining agents

Answer: Accelerators

 

The most commonly used admixture which prolongs the setting and hardening time is

Gypsum

Calcium Chloride

Sodium Silicate

All of the above

Answer: Gypsum

 

The percentage of voids in cement is approximately

25%

40%

60%

80%

Answer: 40%

 

The strength of concrete after one year as compared to 28 days strength is about

10 to 15% more

15 to 20% more

20 to 25% more

25 to 50% more

Answer: 20 to 25% more

 

Modulus of rupture of concrete is a measure of

Flexural tensile strength

Direct tensile strength

Compressive strength

Split tensile strength

Answer: Flexural tensile strength

 

In order to obtain the best workability of concrete, the preferred shape of aggregate is

Rounded

Elongated

Angular

All of the above

Answer: Rounded

 

Bulking of sand is maximum if moisture content is about

2%

4%

6%

10%

Answer: 4%

 

For a reinforced concrete section, the shape of shear stress diagram is

0/1

Wholly parabolic

Wholly rectangular

Parabolic above neutral axis and rectangular below neutral axis

Rectangular above neutral axis and parabolic below neutral axis

Answer: Parabolic above neutral axis and rectangular below neutral axis

 

If a beam fails in bond, then its bond strength can be increased most economically by

Increasing the depth of beam

Using thinner bars but more in number

Using thicker bars but less in number

Providing vertical stirrups

Answer: Using thinner bars but more in number

 

If the depth of actual neutral axis in a beam is more than the depth of critical neutral axis, then the beam is called

Balanced Beam

Under-reinforced beam

Over-reinforced beam

None of the above

Answer: Over-reinforced beam

 

If the permissible stress in steel in tension is 140 N/mm2, then the depth of neutral axis for a singly reinforced rectangular balanced section will be

0.35d

0.40d

0.45d

Answer: 0.40d

 

dependent on grade of concrete also

Modulus of elasticity of steel as per IS : 456-2000 shall be taken as

0/1

20 kN/cm2

200 kN/cm2

200kN/mm2

2 x 10^6 kN/cm2

Answer: 200kN/mm2

 

Minimum grade of concrete to be used in reinforced concrete as per IS:456-2000 is

M15

M20

M10

M25

Answer: M15

 

Maximum quantity of water needed per 50 kg of cement for M 15 grade of concrete is

28 liters

30 liters

32 liters

34 liters

Answer: 32 liters

 

In case of hand mixing of concrete, the extra cement to be added is

5%

10%

15%

20%

Answer: 10%

 

For walls, columns and vertical faces of all structural members, the form work is generally removed after

24 to 48 hours

3 days

7 days

14 days

Answer: 24 to 48 hours

 

For a simply supported beam of span 15m, the minimum effective depth to satisfy the vertical deflection limits should be

600 mm

750 mm

900 mm

More than 1 m

Answer: 750 mm

 

According to IS : 456-2000, the column or the strut is the member whose effective length is greater than

The least lateral dimension

2 times the least lateral dimension

3 times the least lateral dimension

4 times the least lateral dimension

Answer: 3 times the least lateral dimension

 

The minimum cover in a slab should neither be less than the diameter of bar nor less than

10 mm

15 mm

25 mm

13 mm

Answer: 15 mm