MCQs on Workability of Concrete
15 questions. Tap an option to check it instantly, then read the solution.
Question 1Easy
Which of the following conditions followed in making concrete reduces the workability of concrete?
Answer: B. Higher aggregate-cement ratio in concrete
A higher aggregate-cement ratio means more aggregate per unit of cement paste. The paste available to lubricate and coat aggregate surfaces decreases, causing increased inter-particle friction and reduced workability.Question 2Easy
Which characteristic of fine aggregates indicates their ability to retain water and affects the workability of concrete or mortar mix?
Answer: D. Water absorption
Water absorption of fine aggregates indicates how much water the aggregate particles can absorb from the mixing water. High water absorption reduces the effective free water in the mix, lowering workability.Question 3Easy
Due to segregation of well-mixed concrete, -
Answer: A. the workability of concrete decreases
Segregation disrupts the homogeneous distribution of materials in concrete. Once segregation occurs, the remaining mix loses its uniform paste-aggregate balance, which reduces its ability to flow and be compacted — lowering workability.Question 4Medium
Consider the below statements with respect to cement concrete and identify the correct statement(s).
Answer: A. Only i
Only statement i is correct. Aggregate size and shape do significantly influence workability. Statement ii is false (higher w/c decreases strength per Abrams' Law). Statement iii is false (maturity depends on both time AND temperature).Question 5Easy
Which of the following types of soil have excellent workability as a construction material?
Answer: A. Well graded gravel
Well-graded gravel (GW in USCS) has excellent workability as a construction material for earthworks because it is easy to compact, drains freely, provides good shear strength, and does not swell or shrink excessively.Question 6Medium
Experimental water absorption tests are done on fine aggregates to find the:
Answer: A. Only (i) Water holding capacity, (ii) Strength of material, and (iii) Quality of material
Water absorption tests on fine aggregates provide information on water holding capacity (i), indirectly indicate strength/quality (ii, iii) through porosity, but do NOT indicate shape (iv). Shape is determined by flakiness index and elongation index tests.Question 7Medium
The recommended slump range (mm) as per IS 456:2000, for hand placed pavement quality concrete is:
Answer: D. 25 - 75
IS 456:2000 specifies a slump of 25-75 mm for pavement quality concrete placed by hand. Pavement concrete needs to be relatively stiff (low slump) to resist deformation under finishing and traffic loads.Question 8Hard
According to IS: 5515, the distance between the bottom of the lower hopper and the top of the cylinder in the Compacting Factor Apparatus is:
Answer: D. 20.0 cm
Per IS 5515, in the Compacting Factor Apparatus, the distance between the bottom of the lower hopper and the top of the cylinder is 20.3 cm ≈ 20.0 cm (approximately 8 inches in the original British standard).Question 9Medium
Two statements: 1: As the compaction factor increases, slump decreases. 2: Slump test helps in qualitatively understand the setting time of concrete.
Answer: C. Statement 1 and Statement 2 are false
Both statements are false. Statement 1 is false: as compaction factor increases, slump also increases (both indicate higher workability). Statement 2 is false: slump test measures consistency/workability, not setting time (setting time is measured by the Vicat needle test).Question 10Easy
What is the height of a slump cone mould used for testing the workability of the concrete?
Answer: C. 30 cm
The slump cone has a height of 30 cm (300 mm). The full dimensions are: top diameter = 10 cm, bottom diameter = 20 cm, height = 30 cm. These are standard dimensions per IS 1199.Question 11Medium
According to IS 456-2000, what is the slump of a medium degree of workability of concrete if placed in heavily reinforced sections like slabs, beams, walls, columns?
Answer: D. 50 - 100 mm
IS 456:2000 specifies a slump of 50-100 mm for concrete placed in heavily reinforced sections (slabs, beams, walls, columns) requiring medium degree of workability. The higher range helps concrete flow through reinforcement bars.Question 12Easy
Which of the following properties of concrete is determined using a compaction factor test?
Answer: D. Workability of concrete
The compaction factor test (IS 1199) is specifically designed to measure the workability of fresh concrete, particularly for mixes of low to medium workability where the slump test is less sensitive.Question 13Medium
Which of the following increases the workability of concrete?
Answer: D. Increasing the aggregate size without any change in the mix of concrete
Increasing the aggregate size (at constant cement, water, and fine aggregate content) reduces total aggregate specific surface area. Less surface area means less water is needed to coat all surfaces, leaving more free water available for lubrication — increasing workability.Question 14Easy
Which of the following decreases the workability of concrete?
Answer: A. Angular aggregates
Angular aggregates have rough, irregular surfaces that create more inter-particle friction than smooth rounded aggregates. This friction resists the flow of concrete, reducing workability. All other options (well-graded, air-entraining, rounded) improve workability.Question 15Medium
Which statements are correct about aggregate shape's influence on strength and workability?
Answer: C. S1 and S4
S1 is correct: rounded aggregates have smooth surfaces giving high workability but weaker mechanical bond giving lower strength. S4 is correct: angular aggregates have rough surfaces giving low workability but strong mechanical interlock giving high strength.