Q1: Define P.C.C.
Ans:P.C.C stands for Plain Cement Concrete, which is a mixture of cement, sand, aggregate, and water without any reinforcement. It is used in flooring, foundations, and leveling surfaces.
Q2: Define R.C.C.
Ans:R.C.C stands for Reinforced Cement Concrete, which is cement concrete strengthened with steel reinforcement bars to resist tensile and compressive stresses.
Q3: Define R.B.C.
Ans:R.B.C stands for Reinforced Brick Concrete, a construction technique where bricks and concrete are used together with reinforcement, typically in slab construction for economical roofing.
Q4: Define slab.
Ans:A slab is a flat horizontal structural element, usually made of reinforced concrete, used to create floors and ceilings in buildings.
Q5: Define one way slab.
Ans:A one-way slab is a slab supported on two opposite sides only, where the load is carried in one direction along the shorter span.
Q6: Define two-way slab.
Ans:A two-way slab is supported on all four sides and carries loads in both directions. It is generally used when the slab's length-to-breadth ratio is less than 2.
Q7: Define waffle slab.
Ans:A waffle slab is a reinforced concrete slab with a grid pattern of ribs on the underside, resembling a waffle. It is used to reduce weight and increase strength, especially for large spans.
Q8: Define ribbed slab.
Ans:A ribbed slab is a type of slab where concrete is placed only in the top slab and along narrow ribs, with voids in between. It reduces dead weight and is used for medium to large spans.
Q9: Define bubble deck slab.
Ans:A bubble deck slab is a type of slab that uses hollow plastic balls (bubbles) embedded in the concrete to reduce its self-weight by removing unused concrete from the middle zone, while maintaining structural strength and stiffness.
Q10: What is meant by main steel?
Ans:Main steel refers to the primary reinforcement bars placed in the direction of maximum bending moment to resist tensile stresses.
Q11: What are the functions of distribution steel?
Ans:Distribution steel (secondary reinforcement) is provided to distribute loads evenly, control shrinkage cracks, and support the main reinforcement in slabs.
Q12: Differentiate between clear concrete cover and effective concrete cover in RCC slab.
Ans:Clear cover is the distance between the outer surface of the concrete and the nearest surface of the reinforcement. Effective cover is the distance from the outer surface to the center of the main reinforcement bar.
Q13: Define self-weight of slab.
Ans:Self-weight of a slab is the weight of the slab itself, calculated based on its density and volume. For RCC, it is usually taken as 25 kN/m³.
Q14: Define live load.
Ans:Live load is the moving load applied to a structure, such as the weight of people, furniture, or vehicles. It is the load that keeps on changing.
Q15: Differentiate between overall depth and effective depth of slab.
Ans:Overall depth is the total thickness of the slab, including cover. Effective depth is the distance from the top surface to the center of the tension reinforcement.
Q16: Define neutral axis.
Ans:The neutral axis is the imaginary axis in a structural member under bending where the fiber experiences zero stress — neither tension nor compression.
Q17: Write down the standard formula to calculate the effective depth of slab.
Ans:NOTE:
Q18: Differentiate between simply supported and cantilever slab.
Ans:
| Aspects | Simply Supported Slab | Cantilever Slab |
|---|
| Support Condition | Supported at both ends | Fixed at one end, free at the other |
| Bending Moment | Bends downward (sagging) in the middle | Bends upward (hogging) at the fixed end |
| Reinforcement | Main bars placed at the bottom (mid-span) | Main bars placed at the top (fixed end) |
| Span | Shorter or moderate spans | Usually, shorter spans due to high bending at the fixed end |
| Examples | Room slabs, floor slabs between beams | Sunshades, balconies, projections without side supports |
Q19: What is the density of RCC in FPS system?
Ans:It is 140 to 150 lb/ft³. A commonly used average is 145 lb/ft³.
Q20: Write down the density of brickwork in FPS system.
Ans:It is 120 to 130 lb/ft³. A commonly used average is 125 lb/ft³.
Q21: How much live load is taken while designing domestic slab for house?
Ans:The live load is usually taken as 2.0 kN/m² (or 40 lb/ft²) for domestic slabs.
