RRB JE Civil Engineering — Solved Practice Question Bank

Q: What grade of concrete is denoted by "M25"? Sol: M25 means the concrete has a characteristic compressive strength of 25 N/mm² at 28 days when tested on standard cubes. Q: Why is a minimum clear cover specified for reinforcement in RCC members? Sol: To protect the steel from corrosion (moisture/chemical ingress) and to provide adequate fire resistance — inadequate cover exposes reinforcement to atmospheric attack, causing rust-induced expansion and concrete cracking/spalling. Q: What is the standard nominal size of a modular brick in India? Sol: 200mm × 100mm × 100mm (nominal, including a 10mm mortar joint); the actual brick size is 190×90×90mm.

Q: In levelling, the staff reading taken immediately after setting up the instrument is called? Sol: Back Sight (BS) — the first reading taken from a new instrument station, used to determine the Height of Instrument. Q: Can two contour lines of different elevation cross each other? Sol: No, except in the rare case of an overhanging cliff or cave, where they are shown as dashed/hidden lines — under normal terrain, contour lines of different values never intersect. Q: What does a Total Station measure that a traditional theodolite cannot? Sol: A Total Station integrates Electronic Distance Measurement (EDM) with angle measurement, giving direct 3D coordinates — a traditional theodolite measures angles only and requires a separate chain/tape for distance.

Q: Water flows through a pipe of diameter 10 cm with Reynolds number 1500. Is the flow laminar or turbulent? Sol: Laminar, since Re = 1500 is below the critical value of 2000 for pipe flow. Q: Which flow-measuring device causes lower head loss — a venturimeter or an orifice meter? Sol: The venturimeter, due to its smooth, gradual converging-diverging profile, causes significantly less head loss than the sudden constriction of an orifice meter. Q: A centrifugal pump is preferred over a reciprocating pump for which application? Sol: High discharge, low head applications (e.g. municipal water supply) — centrifugal pumps convert impeller kinetic energy into pressure and handle large flow rates smoothly, unlike the pulsating delivery of reciprocating pumps.