Q18: The final operation of finishing floors is known as:
Difficulty: Easy
A. Floating
B. Finishing
C. Troweling
D. All options are correct
Correct Answer: C. TrowelingSolution:The final operation in concrete floor finishing is troweling. It follows screeding (levelling) and floating (smoothing) and produces a hard, dense, smooth surface by compressing the cement paste at the surface.
Q19: Which is the best method for curing of concrete flat surfaces?
Difficulty: Medium
A. Spraying water
B. Placing wet gunny bags
C. Stagnating water (ponding)
D. None of these
Correct Answer: C. Stagnating water (ponding)Solution:The ponding (stagnating water) method is the best for flat surfaces. Sand or clay bunds are built to create rectangular bays, which are then filled with water to a depth of 30-50 mm. This ensures continuously wet conditions over the entire surface, providing the most effective and uniform curing.
Q20: Transport of concrete by pumps, is done for a distance of:
Difficulty: Easy
A. 100 m
B. 200 m
C. 300 m
D. 400 m
Correct Answer: D. 400 mSolution:Concrete pumps can transport concrete horizontally up to 400 m and vertically up to 80 m using pipes of 100-200 mm diameter. The concrete (pumpcrete) must have a slump of 80-100 mm for pumpability. Pipes are first lubricated with a 1:2 cement slurry before pumping begins.
Q21: The operation of removing humps and hollows of uniform concrete surface is known as:
Difficulty: Easy
A. Floating
B. Screeding
C. Troweling
D. Finishing
Correct Answer: B. ScreedingSolution:Screeding is the first finishing operation. A straight-edge (screed board) is drawn across the concrete surface with a sawing motion to remove high spots (humps) and fill low spots (hollows), bringing the surface to the required level and grade.
Q22: The purpose of concrete compaction is to:
Difficulty: Easy
A. Increase the density
B. Increase the weight
C. Increase the voids
D. Decrease the setting time
Correct Answer: A. Increase the densitySolution:Compaction removes entrapped air voids, making the concrete more dense. Increased density directly correlates with increased strength and impermeability. Every 1% of removed air void roughly increases strength by ~5%.
Q23: Compaction of concrete by a vibrator is unsuitable if it is:
Difficulty: Medium
A. Dry
B. Earth moist
C. Semi-plastic
D. Plastic
Correct Answer: D. PlasticSolution:Vibrators are suitable for stiff to semi-plastic mixes. When applied to highly plastic (wet, high-slump) concrete, the intense vibration causes segregation — heavy aggregates sink while cement paste and water rise. This destroys the homogeneity of the mix. IS 2505 recommends vibrators for mixes with slump not exceeding 50 mm (5 cm).
Q24: The process of maintaining moisture and temperature conditions of concrete so that concrete develops hardened properties over time is called:
Difficulty: Easy
A. Hardening
B. Softening
C. Setting
D. Curing
Correct Answer: D. CuringSolution:Curing is the deliberate process of controlling moisture content and temperature in fresh and recently hardened concrete to promote continued hydration and strength development. It begins after initial setting and continues for 7-28 days depending on conditions.
Q25: The compaction of concrete improves:
Difficulty: Easy
A. Density
B. Strength
C. Durability
D. All options are correct
Correct Answer: D. All options are correctSolution:Proper compaction expels entrapped air, which simultaneously improves density (fewer voids), strength (greater particle-to-particle contact and paste fill), and durability (reduced permeability prevents ingress of aggressive agents).
Q26: Which vibrator is used for vibrating concrete cubes?
Difficulty: Medium
A. Surface vibrator
B. Internal vibrator
C. Table vibrator
D. Platform vibrator
Correct Answer: C. Table vibratorSolution:A table vibrator (vibrating table) consists of a rigid steel platform mounted on springs with a vibrating mechanism underneath. Concrete moulds (test cubes or cylinders) are clamped to the table and vibrated from below. This is the standard laboratory method for compacting test specimens per IS 516.
Q27: Which process comes after batching in manufacture process of concrete?
Difficulty: Easy
A. Transportation
B. Placing
C. Mixing
D. Compacting
Correct Answer: C. MixingSolution:The concrete manufacturing sequence is: Storage of ingredients → Batching → Mixing → Transportation → Placing → Compacting → Finishing → Curing. Batching measures the ingredients; mixing combines them into a homogeneous concrete.
Q28: Which of the following refers to the process of proper and accurate measurements of concrete ingredients for uniformity of proportion?
Difficulty: Easy
A. Grading
B. Curing
C. Mixing
D. Batching
Correct Answer: D. BatchingSolution:Batching is the process of accurately measuring the concrete ingredients — cement, fine aggregate (sand), coarse aggregate, water, and admixtures — in the specified proportions. Accurate batching ensures uniformity and repeatability of the concrete mix.
Q29: What are the dimensions of a 35-litre farma (gauge box) for measuring aggregates by volume?
Difficulty: Medium
A. L=30 cm, B=25 cm, H=30 cm
B. L=39 cm, B=25 cm, H=32 cm
C. L=27 cm, B=27 cm, H=48 cm
D. L=220 cm, B=25 cm, H=40 cm
Correct Answer: C. L=27 cm, B=27 cm, H=48 cmSolution:A standard 35-litre gauge box has inner dimensions of 27 cm × 27 cm × 48 cm, giving a volume = 0.27 × 0.27 × 0.48 = 0.034992 m³ ≈ 35 litres. This equals the loose volume of one 50 kg bag of OPC cement.
Q30: Which of the following statements is true?
Difficulty: Medium
A. The weight of ingredients of concrete mix is taken in kilograms
B. Water and aggregates are measured in litres
C. The finished concrete is measured in cubic metres
D. All of these
Correct Answer: C. The finished concrete is measured in cubic metresSolution:The most universally correct statement in the context of BOQ and payment is that finished concrete volume is measured in cubic metres (m³). While water is measured in litres and cement in kg, aggregates are typically measured by mass (kg) or volume (m³) — not litres. Option (c) is the universally applicable true statement.
Q31: Pick up the correct statement from the following about concrete mixing:
Difficulty: Medium
A. There should not be any loss of cement from the charged drum of the mixer
B. Cement should be mixed for at least one minute
C. 10% of water is placed in the rotating drum before adding dry material
D. All options are correct
Correct Answer: D. All options are correctSolution:All three are correct good mixing practices: (A) no cement loss from the drum prevents waste and incorrect proportions; (B) minimum 1 minute mixing ensures homogeneity; (C) adding 10% water first prevents dry materials sticking to the drum blades.
Q32: How many methods of batching of concrete are there?
Difficulty: Easy
Correct Answer: A. 2Solution:There are two fundamental methods of batching concrete: (1) Volume batching — using gauge boxes/farmas to measure materials by volume; and (2) Weigh batching — using weigh batchers or scales to measure materials by mass. Weigh batching is more accurate and preferred for structural concrete.
Q33: Membrane curing is done by:
Difficulty: Medium
A. Applying steam on the surface of concrete
B. Applying spray of water on the surface
C. Ponding of water on the surface
D. Applying paraffin or resin-based liquids on the surface
Correct Answer: D. Applying paraffin or resin-based liquids on the surfaceSolution:Membrane curing (also called chemical curing or dry curing) involves applying a liquid chemical compound — typically paraffin wax, resin-based liquids, or bitumen emulsions — that forms a waterproof membrane on the concrete surface. This membrane prevents evaporation of the mixing water already in the concrete, allowing hydration to continue without external water supply.
Q34: Steam curing of concrete is adopted for:
Difficulty: Easy
A. Precast structures
B. Columns
C. Beams
D. Walls
Correct Answer: A. Precast structuresSolution:Steam curing accelerates hydration through elevated temperature and humidity, allowing rapid strength gain (70% of 28-day strength in 4-5 hours). This is ideal for precast concrete production where moulds need to be stripped quickly and reused. It is not practical for cast in-situ elements like columns, beams, and walls.
