What is the recommended slump for RCC columns according to IS 456:2000?
Answer: A
For RCC columns, the recommended slump is 25-50 mm to ensure adequate compaction and workability.
Q.62Medium
Hydration of cement produces which of the following as main products?
Answer: A
CSH (Calcium Silicate Hydrate) and CH (Calcium Hydroxide) are the main hydration products that give strength to concrete.
Q.63Medium
What is the minimum concrete cover for reinforcement in foundations as per IS 456:2000?
Answer: C
IS 456:2000 specifies 50 mm minimum concrete cover for reinforcement in submerged/buried foundations.
Q.64Medium
Which of the following factors increases the compressive strength of concrete?
Answer: C
Pozzolanic materials like fly ash and silica fume react with calcium hydroxide to improve strength and durability.
Q.65Easy
What is the nominal maximum size of coarse aggregate for concrete beams?
Answer: B
For reinforced concrete beams, nominal maximum coarse aggregate size is typically 20 mm to ensure proper placement around reinforcement.
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Q.66Easy
Which standard specifies the code of practice for plain and reinforced concrete in India?
Answer: B
IS 456:2000 is the Indian Standard for plain and reinforced concrete - Code of Practice.
Q.67Medium
What is the typical strength gain pattern of concrete in the first 28 days?
Answer: B
Concrete gains approximately 40-50% strength in 7 days due to rapid hydration, then strength gain slows down gradually.
Q.68Hard
Which chemical compound in cement causes flash setting when exposed to water?
Answer: C
C3A reacts rapidly with water and is responsible for flash setting. Gypsum is added to control this reaction.
Q.69Easy
For a M25 grade concrete, what is the approximate 28-day compressive strength?
Answer: B
M25 designation means the concrete will achieve 25 MPa minimum compressive strength at 28 days with 95% probability.
Q.70Medium
What is the effect of adding admixtures like retarders in concrete?
Answer: B
Retarders delay the setting time of concrete, allowing more time for placement and compaction in large structures.
Q.71Hard
According to Abrams' Law, the relationship between w/c ratio and compressive strength is:
Answer: B
Abrams' Law states that compressive strength decreases exponentially with increase in water-cement ratio.
Q.72Medium
What is the recommended curing period for concrete in normal conditions?
Answer: B
IS 456:2000 recommends minimum 14 days of moist curing for normal Portland cement in normal temperature conditions.
Q.73Easy
Which of the following is a measure of concrete workability?
Answer: A
Slump test is the most common field test to measure the workability and flow characteristics of fresh concrete.
Q.74Hard
Self-compacting concrete (SCC) must achieve a slump flow of:
Answer: C
SCC requires slump flow between 600-800 mm to flow and compact under its own weight without vibration.
Q.75Easy
In the method of sections, when analyzing a truss, the maximum number of members that can be cut in a single section is:
Answer: B
In the method of sections, we can cut maximum 3 members in a single section to ensure we have only 3 unknowns, which can be solved using 3 equilibrium equations (ΣFx=0, ΣFy=0, ΣM=0).
Q.76Easy
The deflection of a cantilever beam of length L carrying a point load W at the free end is:
Answer: A
For a cantilever beam with point load at free end, maximum deflection = WL⁴/(3EI). This is a standard formula in structural analysis.
Q.77Easy
In Castigliano's theorem, the partial derivative of strain energy with respect to a force gives:
Answer: B
Castigliano's first theorem states that ∂U/∂P = δ, where U is strain energy and δ is deflection in the direction of force P.
Q.78Easy
The bending moment diagram for a simply supported beam carrying a uniformly distributed load is:
Answer: B
For UDL on simply supported beam, BMD is parabolic (second-degree curve) with maximum at center.
Q.79Medium
In a two-hinged arch, the number of unknown reactions is:
Answer: B
Two-hinged arch has 2 supports (each with 2 reactions) = 4 unknowns total (horizontal and vertical at each hinge).
Q.80Medium
The influence line for a reaction at support A of a simply supported beam AB is:
Answer: A
Influence line for reaction at A is triangular, varying from 1 at A to 0 at B, representing the reaction at A due to unit load.
