Q1: How does the age of concrete affect its compressive strength, considering the age limit as 28 days with continued curing?
Difficulty: Easy
A. Compressive strength increases as the age of concrete increases
B. Compressive strength increases upto 14 days and continues to decrease on further curing
C. Age of concrete does not affect the compressive strength
D. Compressive strength decreases upto 7 days and continues to decrease further
Correct Answer: A. Compressive strength increases as the age of concrete increasesSolution:Concrete primarily gains strength through the hydration of cement. This ongoing process reduces the effective water-cement ratio over time, leading to continuous (though slowing) strength gain. The maximum strength is largely achieved by 28 days, but gradual gain continues over the concrete’s lifetime.
Q2: Which method of transportation of concrete is useful for transporting concrete to a relatively greater distance from the batching plant?
Difficulty: Easy
A. Pump and pipe line
B. Wheel barrow
C. Transit mixer
D. Crane and bucket method
Correct Answer: C. Transit mixerSolution:A transit mixer is a truck-mounted revolving drum that mixes or agitates concrete during transport over long distances, making it the primary equipment used in Ready Mix Concrete (RMC) operations. The drum rotates at 2-6 rpm during transit to prevent setting.
Q3: As per IS 2770 (Part 1), the load at failure in a pull out test was found to be 180 kN. Calculate the bond strength if the bar diameter is 20 mm and its embedded length into concrete is 300 mm.
Difficulty: Hard
A. 30/π N/mm²
B. 10/π N/mm²
C. 50/π N/mm²
D. 15/π N/mm²
Correct Answer: A. 30/π N/mm²Solution:Bond Strength = Load / (π × bar diameter × embedded length) = (180 × 10³) / (π × 20 × 300) = 180,000 / 6000π = 30/π N/mm².
Q4: As per IS 13311 (Part 1), the natural frequency of transducers for a path length of more than 1500 mm is:
Difficulty: Medium
A. Greater than or equal to 50 kHz
B. Greater than or equal to 10 kHz
C. Greater than or equal to 20 kHz
D. Less than 5 kHz
Correct Answer: C. Greater than or equal to 20 kHzSolution:IS 13311 (Part 1) specifies that for a path length exceeding 1500 mm, the transducer natural frequency should be ≥ 20 kHz. Longer paths require lower frequencies because high-frequency waves attenuate more rapidly over distance.
Q5: Which of the following parts of a rebound test apparatus moves with the mass attached to the spring after bouncing back?
Difficulty: Medium
A. Rider
B. Plunger
C. Release button
D. Scales
Correct Answer: A. RiderSolution:In the rebound hammer test, after the plunger is pushed against the concrete surface, the spring-loaded mass strikes the plunger and rebounds. The Rider is the component that travels with the rebounding mass along the graduated scale, recording the rebound number.
Q6: Which of the following problems are observed during the pouring of freshly prepared concrete in hot weather? (i) Rapid rate of hydration (ii) Quick setting (iii) Greater plastic shrinkage (iv) More finishing times
Difficulty: Medium
A. Only (i)
B. Both (i) and (ii)
C. (i), (ii), (iii) and (iv)
D. Only (i), (ii) and (iii)
Correct Answer: D. Only (i), (ii) and (iii)Solution:Hot weather causes rapid hydration, quick setting, and greater plastic shrinkage — all true. However, finishing time is REDUCED (not increased) in hot weather because concrete stiffens faster, leaving less time for the finisher to work the surface. Statement (iv) is therefore incorrect.
Q7: A proper compaction of freshly prepared concrete results in: (i) Achieving maximum strength (ii) Expelling entrapped air (iii) Change in fineness modulus of aggregate
Difficulty: Easy
A. Only (i)
B. Both (i) and (ii)
C. (i), (ii) and (iii)
D. Only (ii)
Correct Answer: B. Both (i) and (ii)Solution:Proper compaction expels entrapped air (ii) and allows the concrete to achieve its maximum possible strength (i). However, compaction has absolutely no effect on the fineness modulus of the aggregate (iii), which is a property determined by gradation analysis — a physical property of the aggregate itself, not changed by compacting the mix.
Q8: As per IS 7861 (Part 1), concreting done at atmospheric temperatures above ________ is termed as hot weather concreting.
Difficulty: Easy
A. 40°C
B. 37°C
C. 47°C
D. 55°C
Correct Answer: A. 40°CSolution:IS 7861 (Part 1): 1975 defines hot weather concreting as any concreting operation carried out at atmospheric temperatures above 40°C (excluding steam curing). Special precautions are mandatory to prevent quality deterioration.
Q9: As per IS 7861 (Part 2), concreting done at atmospheric temperature ________ or below is termed as cold weather concreting.
Difficulty: Easy
A. 7°C
B. 5°C
C. 10°C
D. 3°C
Correct Answer: B. 5°CSolution:IS 7861 (Part 2) defines cold weather concreting as any concreting operation where the atmospheric temperature is 5°C or below. At this temperature, hydration slows drastically, and there is risk of freezing of mix water before concrete gains strength.
Q10: The application of curing on the prepared concrete results in:
Difficulty: Easy
A. Decrease in compressive strength
B. Increase in air entrainment
C. No change in strength
D. Increase in compressive strength
Correct Answer: D. Increase in compressive strengthSolution:Curing provides moisture and temperature conditions necessary for continued hydration of cement. As hydration progresses, the capillary pores fill with C-S-H gel, increasing density and strength. Without curing, hydration stops prematurely and the concrete never reaches its design strength.
Q11: For compacting plain concrete road surface of thickness less than 20 cm, we use:
Difficulty: Medium
A. Internal vibrator
B. Screed vibrator
C. Form vibrator
D. None of these
Correct Answer: B. Screed vibratorSolution:Screed vibrators (surface vibrators) operate on the top surface of the concrete and are ideal for shallow sections like roads, slabs, and canal linings less than 20 cm thick. Internal (immersion) vibrators are needed for deeper sections (60 cm or more), where screed vibrators cannot penetrate effectively.
Q12: Which of the following is the result of proper batching of concrete? A. Economy B. Durability C. Workability D. Strength
Difficulty: Easy
A. A and B only
B. A, B and C only
C. A and D only
D. A, B, C and D (all)
Correct Answer: D. A, B, C and D (all)Solution:Proper batching ensures accurate measurement of all ingredients — cement, aggregates, water, and admixtures — in the specified proportions. This directly delivers economy (no wasted cement), durability (correct w/c ratio), workability (correct water content), and strength (correct cement content).
Q13: ________ are used to press mortar and spread it uniformly.
Difficulty: Easy
A. Trowel
B. Aluminium rod
C. Floats
D. Brush
Correct Answer: C. FloatsSolution:Floats are flat boards (typically wooden or steel, 60–150 cm long and 20 cm wide) used after screeding to press the mortar and spread it uniformly across the concrete surface. Floating removes surface irregularities left by the screed and closes the surface for troweling.
Q14: In small works, concrete is transported using:
Difficulty: Easy
A. Conveyer belts
B. Pumps
C. Pans
D. Buckets
Correct Answer: C. PansSolution:For small works and very short distances, concrete is manually transported in pans (cane or metal baskets) carried on workers’ heads. While labour-intensive, this method is simple, requires no equipment, and is economical for small volumes.
Q15: How many types of machine mixers of concrete are available?
Difficulty: Medium
Correct Answer: A. 2 (Batch and Continuous) — Note: Commission invalidated this question in the revised answer keySolution:This question was invalidated by the examining commission. However, the fundamental classification used in most Indian civil engineering textbooks is 2 main types: (1) Batch Mixers and (2) Continuous Mixers. Batch mixers (tilting drum, non-tilting drum, reversing drum, pan mixer, transit mixer) produce concrete in discrete batches; continuous mixers produce a steady stream.
Q16: For concreting tunnel linings, transportation of concrete is done by which of the following?
Difficulty: Easy
A. Pans
B. Wheel barrows
C. Containers
D. Pumps
Correct Answer: D. PumpsSolution:Tunnel linings are poured in confined, often long, curved spaces where conventional transport methods cannot reach. Pumps are the only practical method — they can push concrete through flexible pipes to any point along the tunnel alignment, including overhead sections of the lining.
Q17: Compacting of concrete is done to:
Difficulty: Easy
A. Place concrete on flat surface
B. Remove air bubbles
C. Place concrete on sloping surface
D. Introduce air bubbles
Correct Answer: B. Remove air bubblesSolution:During mixing and placing, air gets entrapped between aggregate particles and in the cement paste, creating voids. Compaction (vibration, tamping, or rodding) causes these air bubbles to rise to the surface and escape, making the concrete dense, impermeable, and strong.
