Showing 21–30 of 53 questions
What is the typical strength gain pattern of concrete in the first 28 days?
A
Linear growth throughout
B
Rapid growth in first 7 days, then slower
C
Slow initial growth, then rapid after 14 days
D
Constant growth at all stages
Correct Answer:
B. Rapid growth in first 7 days, then slower
EXPLANATION
Concrete gains approximately 40-50% strength in 7 days due to rapid hydration, then strength gain slows down gradually.
Which of the following factors increases the compressive strength of concrete?
A
Increase in water-cement ratio
B
Decrease in curing time
C
Use of pozzolanic materials
D
Increase in slump value
Correct Answer:
C. Use of pozzolanic materials
EXPLANATION
Pozzolanic materials like fly ash and silica fume react with calcium hydroxide to improve strength and durability.
What is the minimum concrete cover for reinforcement in foundations as per IS 456:2000?
A
25 mm
B
40 mm
C
50 mm
D
75 mm
EXPLANATION
IS 456:2000 specifies 50 mm minimum concrete cover for reinforcement in submerged/buried foundations.
Hydration of cement produces which of the following as main products?
A
Calcium Silicate Hydrate and Calcium Hydroxide
B
Silicon Dioxide and Aluminum Oxide
C
Iron Oxide and Magnesium Oxide
D
Calcium Carbonate only
Correct Answer:
A. Calcium Silicate Hydrate and Calcium Hydroxide
EXPLANATION
CSH (Calcium Silicate Hydrate) and CH (Calcium Hydroxide) are the main hydration products that give strength to concrete.
What is the recommended slump for RCC columns according to IS 456:2000?
A
25-50 mm
B
50-100 mm
C
100-150 mm
D
150-200 mm
Correct Answer:
A. 25-50 mm
EXPLANATION
For RCC columns, the recommended slump is 25-50 mm to ensure adequate compaction and workability.
What is the water-cement ratio for M20 grade concrete as per IS 456:2000?
A
0.40
B
0.45
C
0.50
D
0.55
EXPLANATION
For M20 concrete, the maximum water-cement ratio is 0.55 to achieve the specified 28-day compressive strength.
The principle of virtual displacements is applicable to:
A
Determinate structures only
B
Indeterminate structures only
C
Both determinate and indeterminate structures
D
Rigid bodies only
Correct Answer:
C. Both determinate and indeterminate structures
EXPLANATION
Virtual work principle applies universally to all structures, both determinate and indeterminate, and rigid/deformable bodies.
In slope-deflection method, the fixed-end moment for a fixed beam with UDL w over length L is:
A
wL²/12
B
wL²/8
C
wL²/6
D
wL²/4
Correct Answer:
A. wL²/12
EXPLANATION
Fixed-end moment for fixed beam with UDL = wL²/12 at each end (opposite signs).
For a continuous beam with equal spans and equal loads, the negative moment at interior support is maximum at:
A
First interior support
B
Second interior support
C
Middle interior support
D
All interior supports equally
Correct Answer:
D. All interior supports equally
EXPLANATION
For symmetrical continuous beam with equal spans and loads, negative moments at all interior supports are equal.
In a three-hinged arch, the additional hinge at crown provides:
A
One additional equilibrium equation
B
Two additional constraints
C
Reduces indeterminacy to zero
D
Increases bending moment
Correct Answer:
C. Reduces indeterminacy to zero
EXPLANATION
Three-hinged arch has 4 reactions with 3 global + 1 local equilibrium equation at crown, making it statically determinate (DSI=0).
