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RBSE SS Voc Construction study materials
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RBSE SS Voc Construction practice questions

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Question 1Construction Materials and Their Properties

Which property of a construction material describes its ability to return to its original shape after a load is removed?

  1. Plasticity
  2. Elasticity Correct answer.
  3. Brittleness
  4. Ductility

Explanation

Elasticity is the capacity of a material to deform under stress and then recover its original dimensions once the load is released, as seen in steel within its elastic range. The other terms describe permanent deformation or sudden failure, not recovery.

Question 2Construction Materials and Their Properties

A standard cement mortar cube is tested and fails suddenly with almost no visible deformation beforehand. Which material property does this behaviour indicate?

  1. Brittle failure Correct answer.
  2. Elastic recovery
  3. High toughness
  4. High ductility

Explanation

Brittle failure occurs when a material fractures with little or no plastic deformation, which is typical of cement mortar and concrete under compression. Tough materials absorb energy and deform noticeably before breaking, which is not the case here.

Question 3Construction Materials and Their Properties

What is the approximate dry bulk density range of ordinary structural concrete made with normal-weight aggregates?

  1. 1200 to 1400 kg/m³
  2. 2200 to 2600 kg/m³ Correct answer.
  3. 600 to 900 kg/m³
  4. 3500 to 4000 kg/m³

Explanation

Normal-weight structural concrete typically has a dry density of about 2200 to 2600 kg/m³, depending on aggregate type and mix proportions. Lower ranges correspond to lightweight concrete, and the highest range is far above typical concrete density.

Question 4Construction Materials and Their Properties

Which constituent of ordinary Portland cement is primarily responsible for early strength development?

  1. Gypsum (calcium sulfate)
  2. Dicalcium silicate (C2S)
  3. Tricalcium silicate (C3S) Correct answer.
  4. Tetracalcium aluminoferrite (C4AF)

Explanation

Tricalcium silicate hydrates rapidly and contributes most of the early strength gain in Portland cement. Dicalcium silicate hydrates slowly and mainly contributes to later strength, while gypsum controls set time.

Question 5Construction Materials and Their Properties

Which test is used to determine the consistency of fresh cement paste and thereby estimate the water requirement of a cement sample?

  1. Le Chatelier soundness test
  2. Compressive strength test on mortar cubes
  3. Vicat apparatus test
  4. Standard consistency test with Vicat plunger Correct answer.

Explanation

The standard consistency test uses a Vicat plunger to find the water content at which the paste reaches a defined penetration, indicating normal consistency. This value is then used to prepare specimens for setting-time and soundness tests.

Question 6Construction Materials and Their Properties

A concrete mix is required to resist freezing and thawing in a wet environment. Which feature most directly improves its freeze-thaw durability?

  1. Higher cement content
  2. Entrained air voids of suitable spacing Correct answer.
  3. Increased sand proportion
  4. Larger maximum aggregate size

Explanation

Air entrainment creates a network of closely spaced small voids that relieve hydraulic pressure from freezing water, greatly improving freeze-thaw resistance. Increasing cement content or aggregate size does not provide this pressure relief and can worsen cracking.

Question 7Construction Materials and Their Properties

Which of the following best describes the role of gypsum in the manufacture of Portland cement?

  1. It increases the density of the hardened paste.
  2. It retards the flash set of cement paste. Correct answer.
  3. It accelerates the hydration of C3S.
  4. It acts as a filler to reduce cost.

Explanation

Gypsum is interground with clinker to control the reaction of tricalcium aluminate with water, preventing rapid stiffening known as flash set. Without it, concrete would lose workability almost immediately after mixing.

Question 8Construction Materials and Their Properties

A material sample has a saturated surface-dry mass of 500 g, an oven-dry mass of 480 g, and a bulk volume of 200 cm³. What is its apparent (bulk) specific gravity on an oven-dry basis?

  1. 2.00
  2. 2.40 Correct answer.
  3. 2.50
  4. 2.60

Explanation

Bulk specific gravity is the oven-dry mass divided by the bulk volume (in the same units, with water density taken as 1 g/cm³). Here 480 g ÷ 200 cm³ = 2.40. The saturated surface-dry value would give 2.50, but the question specifies the oven-dry basis.

Question 9Construction Materials and Their Properties

Which statement correctly distinguishes bulk density from relative density (specific gravity)?

  1. Both are dimensionless ratios comparing mass to volume.
  2. Bulk density has units of mass per volume, while relative density is dimensionless. Correct answer.
  3. Both are expressed in newtons per cubic metre.
  4. Bulk density is dimensionless, while relative density is expressed in kg/m³.

Explanation

Bulk density expresses mass per unit volume and therefore carries units such as kg/m³. Relative density compares a material's density with that of water and is a dimensionless ratio.

Question 10Construction Materials and Their Properties

Which aggregate characteristic most directly reduces the workability of a concrete mix at a fixed water content?

  1. Rounded particle shape
  2. Low water absorption
  3. High angularity and rough surface texture Correct answer.
  4. Uniform grading

Explanation

Angular, rough-textured particles increase interparticle friction and require more paste to achieve a given workability. Rounded, smooth particles reduce friction, and uniform grading also aids workability.

Question 11Construction Materials and Their Properties

Which of the following is the principal reason for limiting the chloride content of concrete in reinforced structures?

  1. It accelerates the evaporation of mixing water.
  2. It promotes corrosion of embedded steel reinforcement. Correct answer.
  3. It increases the compressive strength of concrete.
  4. It reduces the density of hardened concrete.

Explanation

Chloride ions depassivate the protective oxide layer on steel and, in the presence of moisture and oxygen, promote corrosion that can crack and spall the concrete. Limits on chloride content are therefore specified for reinforced and prestressed concrete.

Question 12Construction Materials and Their Properties

Which type of cement is most suitable for mass concrete where low heat of hydration is required?

  1. Ordinary Portland cement
  2. Low-heat Portland cement or slag-blended cement Correct answer.
  3. White Portland cement
  4. Rapid-hardening Portland cement

Explanation

Low-heat cements and slag-blended cements contain less tricalcium aluminate and tricalcium silicate, so they generate heat more slowly and reduce the risk of thermal cracking in large pours. Rapid-hardening cement does the opposite.

Question 13Construction Materials and Their Properties

What is the typical purpose of adding a superplasticiser to a concrete mix?

  1. To accelerate setting time
  2. To reduce the density of the mix
  3. To entrain air for freeze-thaw resistance
  4. To increase workability at low water-cement ratio Correct answer.

Explanation

Superplasticisers are high-range water reducers that disperse cement particles, allowing a flowing mix at a low water-cement ratio or a workable mix with less water. This improves strength and durability through reduced water demand.

Question 14Construction Materials and Their Properties

Which of the following best explains why concrete is normally strong in compression but weak in tension?

  1. Steel reinforcement is absent from the tensile zone.
  2. Water evaporates from the tensile face during loading.
  3. Cement paste and the interfacial transition zone contain microcracks that open under tension. Correct answer.
  4. Aggregate particles dissolve under tensile stress.

Explanation

Concrete is a brittle composite with microcracks in the paste and at the paste-aggregate interface; tensile stress propagates these cracks, causing early failure. Under compression, these defects tend to close and load is transferred through aggregate interlock.

Question 15Construction Materials and Their Properties

Which property of hardened concrete is most directly measured by the rebound hammer test?

  1. Depth of carbonation
  2. Modulus of elasticity
  3. Surface hardness as an index of compressive strength Correct answer.
  4. Tensile splitting strength

Explanation

The rebound hammer measures the rebound of a spring-driven mass from the concrete surface, which correlates with surface hardness and hence provides an index of compressive strength. It does not directly measure tensile strength, stiffness, or carbonation.

Question 16Construction Materials and Their Properties

Which of the following is the main function of aggregates in a concrete mix?

  1. To act as an inert filler forming the skeleton of the concrete Correct answer.
  2. To regulate the setting time of the paste
  3. To supply air voids for durability
  4. To provide the chemical reaction that binds the mix

Explanation

Aggregates are generally inert granular materials that form the structural skeleton of concrete, occupying most of the volume and reducing shrinkage compared with pure paste. Binding is provided by the hydrated cement paste, not by the aggregate.

Question 17Construction Materials and Their Properties

Which grading characteristic of fine aggregate is indicated by a fineness modulus of about 2.2?

  1. A coarse sand with a high proportion of large particles
  2. A fine sand with a high proportion of small particles Correct answer.
  3. A gap-graded aggregate with missing mid-size fractions
  4. A well-graded gravel with large maximum size

Explanation

A lower fineness modulus indicates a finer sand, because finer particles reduce the average particle size and lower the index. Typical fine sand falls around 2.2 to 2.6, while coarser sands give higher values.

Question 18Construction Materials and Their Properties

A concrete cube of 150 mm side fails at a load of 540 kN. What is the compressive strength?

  1. 24 MPa Correct answer.
  2. 36 MPa
  3. 54 MPa
  4. 12 MPa

Explanation

The loaded area is 150 mm × 150 mm = 22,500 mm². Dividing 540,000 N by 22,500 mm² gives 24 N/mm², or 24 MPa. The calculation requires converting kilonewtons to newtons and squaring the side length.

Question 19Construction Materials and Their Properties

Which of the following materials is classified as a lightweight aggregate used to reduce concrete density?

  1. Crushed limestone
  2. River sand
  3. Expanded clay Correct answer.
  4. Crushed granite

Explanation

Expanded clay is produced by firing clay to create a porous, low-density particle, making it a common lightweight aggregate. Granite, sand, and limestone are normal-weight materials.

Question 20Construction Materials and Their Properties

Which of the following best describes the purpose of curing concrete?

  1. To keep concrete moist so cement hydration can continue and strength can develop Correct answer.
  2. To lower the temperature of the concrete to freezing point
  3. To dry the concrete rapidly and increase surface hardness
  4. To remove excess cement from the surface

Explanation

Curing maintains adequate moisture and temperature so that cement hydration continues after initial set, allowing strength and durability to develop. Premature drying stops hydration and causes shrinkage cracking and a weak surface layer.

Question 21Construction Materials and Their Properties

Which statement about the water-cement ratio of a concrete mix is correct?

  1. Increasing the water-cement ratio generally reduces strength and increases permeability. Correct answer.
  2. The water-cement ratio has no effect on strength once the mix is compacted.
  3. Increasing the water-cement ratio generally increases strength and reduces permeability.
  4. The water-cement ratio affects only the colour of hardened concrete.

Explanation

Excess water increases the porosity of the paste after evaporation, reducing strength and increasing permeability. A lower water-cement ratio, while maintaining workability, generally produces stronger and less permeable concrete.

Question 22Construction Materials and Their Properties

Which of the following describes the soundness of cement?

  1. The rate at which cement paste gains compressive strength
  2. The ability of cement paste to retain its volume after setting without disruptive expansion Correct answer.
  3. The capacity of cement to entrain air during mixing
  4. The ability of hardened cement paste to resist abrasion

Explanation

Soundness refers to the ability of set cement paste to maintain volume without harmful expansion, often caused by free lime or magnesia. The Le Chatelier test is used to check this property.

Question 23Construction Materials and Their Properties

Which of the following best explains why a low water-cement ratio concrete may need a superplasticiser?

  1. To increase the heat of hydration
  2. To achieve adequate workability without adding extra water Correct answer.
  3. To reduce the cost of cement
  4. To accelerate the final setting time

Explanation

Lowering the water-cement ratio reduces workability, so a superplasticiser disperses cement particles and restores flow without adding water. This preserves the strength and durability benefits of the low water content.

Question 24Construction Materials and Their Properties

A sample of aggregate has a bulk specific gravity of 2.65 and a water absorption of 1.5 percent. What does this absorption value most directly indicate?

  1. The aggregate will contribute water to the mix rather than absorb it.
  2. The aggregate is saturated and should be dried before use.
  3. The aggregate can absorb about 1.5 percent of its oven-dry mass in water. Correct answer.
  4. The aggregate has a very high porosity unsuitable for concrete.

Explanation

Water absorption expresses the mass of water taken up by an oven-dry aggregate as a percentage of its dry mass, so 1.5 percent means it can absorb that fraction. This affects the effective water content of the mix and must be accounted for in batching.

Question 25Construction Materials and Their Properties

Which of the following is the correct order of the main stages in the manufacture of Portland cement?

  1. Clinker cooling, raw grinding, burning, gypsum addition
  2. Gypsum addition, burning, raw grinding, clinker cooling
  3. Raw material crushing and grinding, burning in kiln, clinker cooling, grinding with gypsum Correct answer.
  4. Burning, gypsum addition, raw grinding, clinker cooling

Explanation

Cement manufacture begins with crushing and grinding of raw materials, followed by burning in a rotary kiln to form clinker, cooling of the clinker, and finally grinding with gypsum to produce cement. Any other order misplaces the kiln stage or the gypsum addition.

Question 26Construction Materials and Their Properties

Which of the following best describes the setting time of cement?

  1. The time required for the cement paste to lose its plasticity and begin to harden Correct answer.
  2. The time required for the cement to be ground to the required fineness
  3. The time required for the cement paste to achieve its design compressive strength
  4. The time required for the cement to cool after leaving the kiln

Explanation

Setting time refers to the period during which a cement paste transitions from a plastic, workable state to a rigid, hardened state. It is commonly divided into initial and final setting times, measured with a Vicat apparatus, and is distinct from hardening or strength gain, which continues long after setting.

Question 27Construction Materials and Their Properties

Which of the following is the most appropriate test for determining the soundness of cement?

  1. Vicat test
  2. Le Chatelier test Correct answer.
  3. Compressive strength test
  4. Blaine air permeability test

Explanation

The Le Chatelier test measures the expansion of a cement paste specimen after curing and boiling, indicating the presence of uncombined lime or magnesia that can cause unsoundness. The Vicat test measures setting time, the compressive strength test measures strength, and the Blaine test measures fineness.

Question 28Construction Materials and Their Properties

A concrete mix has a water-cement ratio of 0.45 by mass. If the cement content is 400 kg/m³, what is the water content in kg/m³?

  1. 160
  2. 220
  3. 180 Correct answer.
  4. 200

Explanation

The water content is calculated as water-cement ratio multiplied by cement content: 0.45 × 400 = 180 kg/m³. This is the mass of water per cubic metre of concrete for the given mix proportions.

Question 29Construction Materials and Their Properties

Which of the following best explains why air entrainment improves the freeze-thaw resistance of concrete?

  1. It accelerates the hydration of cement particles
  2. It creates closely spaced voids that allow water to expand without damaging the paste Correct answer.
  3. It increases the compressive strength of the concrete
  4. It reduces the water-cement ratio required for workability

Explanation

Air-entraining admixtures produce numerous tiny, evenly distributed air bubbles in the concrete. When water in the pores freezes and expands, these voids provide space to accommodate the expansion, relieving pressure and preventing cracking and scaling. Air entrainment typically reduces strength slightly and does not accelerate hydration.

Question 30Construction Materials and Their Properties

A concrete mix is being designed for a reinforced concrete beam exposed to a marine environment. Which of the following cement types is most suitable to resist sulfate attack?

  1. Type V (sulfate-resisting Portland cement) Correct answer.
  2. Type III (high early strength Portland cement)
  3. Type I (ordinary Portland cement)
  4. Type II (moderate sulfate-resisting Portland cement)

Explanation

Type V cement has the lowest tricalcium aluminate content among the standard types, giving it the highest resistance to sulfate attack, which makes it suitable for severe marine exposure. Type II offers only moderate sulfate resistance, while Type I and Type III provide little or none.

Question 31Building Construction Techniques and Components

In a traditional brick-on-edge (Rat-Trap) bond wall, what is the primary structural advantage over a standard English bond of equal thickness?

  1. It allows the wall to carry heavier vertical point loads on the inner leaf
  2. It eliminates the need for any mortar in the inner cavity
  3. It increases the number of header courses per metre of height
  4. It reduces dead load while keeping the wall thickness and lateral stability Correct answer.

Explanation

Rat-trap bond places bricks on edge in alternate courses so the wall keeps its overall thickness and the two leaves are tied by the same bricks, but roughly 20-25 percent less brickwork and mortar are used. The lower self-weight reduces dead load on foundations without sacrificing stability. It is not a load-bearing improvement for concentrated loads, and mortar is still required throughout.

Question 32Building Construction Techniques and Components

A damp-proof course (DPC) is to be laid in a load-bearing masonry wall. Which material and placement satisfies good practice?

  1. A vertical bitumen coat applied only to the external face up to sill level
  2. A layer of broken brick soling placed below the foundation concrete
  3. A 100 mm thick cement concrete layer placed at floor level
  4. A flexible polythene or bituminous felt membrane laid horizontally at plinth level across the full wall thickness Correct answer.

Explanation

A DPC must be continuous, impervious and horizontal across the full thickness of the wall at plinth level to stop rising damp from the foundation soil. Flexible membranes such as polythene or bituminous felt are standard for this purpose. A thick concrete layer is not impervious enough and broken soling belongs below the footing, not in the wall.

Question 33Building Construction Techniques and Components

Which type of foundation is most appropriate for a multi-storey framed building on soil of low bearing capacity where shallow footings would be excessively large?

  1. Strip footing running under all external walls
  2. Raft foundation covering the entire footprint Correct answer.
  3. Stepped footing following the slope of the ground
  4. Isolated pad footings under each column

Explanation

A raft spreads the building load over the whole plan area, lowering contact pressure where soil bearing capacity is low and shallow pads would become uneconomically large. It also improves uniformity of settlement in framed structures. Isolated and strip footings concentrate load over small areas and would need impractical sizes on weak soil.

Question 34Building Construction Techniques and Components

In a English bond wall, what is the standard relationship between a queen closer and the quoin?

  1. A queen closer is placed at mid-length of every stretcher course
  2. A queen closer is placed next to the quoin header to avoid a continuous vertical joint Correct answer.
  3. A queen closer replaces every fourth header in the facing course
  4. A queen closer is used only in half-brick partition walls

Explanation

In English bond a queen closer is inserted after the quoin header so that the following stretcher does not create a vertical joint aligned with the header below. This preserves the bond and prevents a continuous vertical line of joints at the corner. Closers are not distributed mid-length or used to replace headers systematically.

Question 35Building Construction Techniques and Components

A simply supported RCC slab spans 4 m and carries a uniformly distributed load. Which reinforcement detail is correct for the top zone near the supports?

  1. Full main reinforcement is required at the top throughout the span
  2. Main steel is shifted entirely to the top to resist hogging
  3. No reinforcement is needed at the top because the slab is simply supported
  4. Nominal distribution steel alone is provided; main steel is at the bottom Correct answer.

Explanation

In a simply supported slab the sagging moment places the main reinforcement at the bottom of the span, while the top near supports carries little or no bending and only nominal distribution steel is needed there. Main steel is not shifted to the top because hogging is negligible at simple supports. Some top steel may be provided for crack control but not full main reinforcement.

Question 36Building Construction Techniques and Components

A brick masonry wall 230 mm thick is to be provided with an opening 1.2 m wide. What is the most suitable lintel type where headroom is limited and the wall above is lightly loaded?

  1. A steel channel lintel spanning the opening
  2. A reinforced concrete lintel cast in situ
  3. A wooden lintel embedded in the wall
  4. A brick lintel with a relieving arch above Correct answer.

Explanation

A brick lintel with a relieving arch uses the arch action to carry the wall above and needs less construction depth than a flat RCC lintel, which suits limited headroom and light loads. It is economical in brickwork and traditional in load-bearing masonry. RCC lintels are stronger but deeper, and timber lintels are unsuitable for permanent damp-prone walls.

Question 37Building Construction Techniques and Components

In a load-bearing brick wall of a two-storey building, which measure best controls the risk of differential settlement cracking between the two storeys?

  1. Increasing the mortar ratio to 1:3 throughout
  2. Using a richer mix only in the top storey masonry
  3. Providing a continuous plinth beam and uniform footing width under all walls Correct answer.
  4. Reducing the wall thickness abruptly at the first-floor level

Explanation

Differential settlement arises when parts of the structure are loaded or supported differently, so a continuous plinth beam and uniform footing widths distribute load evenly and reduce relative movement. Abrupt changes in wall thickness or mix create stiffness discontinuities that concentrate cracking. A richer mortar alone does not address the underlying settlement mechanism.

Question 38Building Construction Techniques and Components

A concrete floor is to be laid over a ground-floor slab-on-grade. Which sequence gives the correct build-up from the soil upwards?

  1. Hardcore, sand blinding, DPC membrane, concrete slab, screed Correct answer.
  2. Sand blinding, DPC membrane, hardcore, concrete slab, screed
  3. Concrete slab, hardcore, DPC membrane, sand blinding, screed
  4. DPC membrane, hardcore, concrete slab, sand blinding, screed

Explanation

The correct build-up starts with compacted hardcore to provide a stable, drained base, then sand blinding to protect the membrane, then the DPC or damp-proof membrane, then the concrete slab, and finally the screed as the finished surface. Placing hardcore above the slab or membrane defeats the purpose of each layer.

Question 39Building Construction Techniques and Components

Which statement about the function of a sill in a masonry wall is accurate?

  1. It sheds rainwater away from the wall face below an opening Correct answer.
  2. It provides the bearing surface for a floor joist
  3. It transfers roof loads to the lintel
  4. It ties the two leaves of a cavity wall together

Explanation

A sill is the projecting, sloped member at the base of a window or opening that throws rainwater clear of the wall below, protecting the masonry from staining and damp penetration. It does not carry roof loads, tie cavity leaves, or support floor joists. The projection and slope are what make it effective.

Question 40Building Construction Techniques and Components

A cavity wall is to be built with a 50 mm cavity. Which component is essential to ensure the two leaves act together structurally?

  1. Vertical expansion joints at every 3 m
  2. Weep holes at the base of the inner leaf
  3. Wall ties of galvanised or stainless steel at specified spacing Correct answer.
  4. A continuous layer of mortar filling the cavity

Explanation

Wall ties are the only element that structurally connects the two leaves, transferring lateral loads and restraining the outer leaf. They must be corrosion-resistant and spaced to the specified pattern. Filling the cavity with mortar would create a bridge for moisture and defeat the purpose of the cavity.

Question 41Building Construction Techniques and Components

In a reinforced concrete column, why is a minimum number of longitudinal bars and a maximum spacing of lateral ties specified?

  1. To reduce the volume of concrete required in the column
  2. To increase the column's thermal insulation
  3. To allow the column to be cast without formwork
  4. To confine the concrete and prevent buckling of longitudinal bars Correct answer.

Explanation

Lateral ties confine the concrete core, restrain the longitudinal bars against buckling, and hold the cage in position during casting. The minimum bar number ensures the section can resist bending from eccentricity and continuity. Ties do not reduce concrete volume or provide insulation, and formwork is still required.

Question 42Building Construction Techniques and Components

A retaining wall 3 m high retains dry granular backfill. Which feature most directly reduces the lateral earth pressure acting on the wall?

  1. Providing a drainage layer and weep holes behind the wall Correct answer.
  2. Using a richer concrete mix in the stem
  3. Adding a coping at the top of the wall
  4. Increasing the wall thickness at the base

Explanation

Lateral earth pressure depends strongly on the water content of the backfill; drainage behind the wall and weep holes prevent pore water pressure from building up, keeping pressure close to the dry active value. Increasing thickness or mix strength improves resistance but does not reduce the load. A coping protects the top but does not affect earth pressure.

Question 43Building Construction Techniques and Components

Which type of pile derives most of its capacity from friction along the shaft rather than from end bearing?

  1. Friction pile in soft clay Correct answer.
  2. Under-reamed pile with a bulb
  3. End-bearing pile founded on rock
  4. Bored pile socketed into hard strata

Explanation

A friction pile transfers load to the surrounding soil through shaft friction along its length, which suits soft clays where a suitable bearing stratum is deep. End-bearing and socketed piles rely on the resistance at the toe, and an under-reamed pile uses an enlarged bulb for bearing. The distinction is where the load is transferred.

Question 44Building Construction Techniques and Components

A plastered masonry wall shows a horizontal crack just below the ceiling line. Which cause is most consistent with this pattern?

  1. Expansion of the roof slab or truss pushing the wall outward Correct answer.
  2. Sulphate attack in the foundation concrete
  3. Shrinkage of the plaster due to rapid drying
  4. Settlement of the central portion of the footing

Explanation

A horizontal crack near the top of a wall is characteristic of roof expansion or thermal movement pushing the wall outward, often accompanied by cracking at corners. Sulphate attack and central settlement produce different patterns, and plaster shrinkage gives fine map cracking rather than a single horizontal line. The location and orientation point to roof movement.

Question 45Building Construction Techniques and Components

Which roof covering is most suitable for a steeply pitched roof of 40 degrees on a domestic building in a heavy-rainfall region?

  1. Flat bituminous membrane
  2. Precast concrete flooring planks
  3. Mangalore tiles laid with a minimum lap Correct answer.
  4. Glass-reinforced plastic sheets without laps

Explanation

Mangalore tiles are designed for pitched roofs and, when laid with the specified head lap and side lap on a 40-degree slope, shed heavy rain effectively. Flat membranes are for low-slope roofs, and GRP sheets need proper end and side laps to prevent leakage. Concrete planks are a flat-roof or floor element, not a pitched covering.

Question 46Building Construction Techniques and Components

In a steel-framed building, what is the primary function of a gusset plate at a beam-to-column connection?

  1. To increase the span capacity of the beam
  2. To provide thermal insulation at the joint
  3. To allow the beam to rotate freely under load
  4. To distribute connection forces over a larger area of the member Correct answer.

Explanation

A gusset plate spreads the concentrated forces from bolts or welds over a larger area of the connected members, reducing local stress and enabling a practical connection detail. It does not provide insulation, permit free rotation, or change the beam's span capacity. Its role is force distribution at the joint.

Question 47Building Construction Techniques and Components

A stair in a residential building has a floor-to-floor height of 3.0 m. With a riser of 150 mm, how many risers and what going would give a comfortable proportion using the 2R + G = 600 mm rule?

  1. 20 risers with a 300 mm going Correct answer.
  2. 18 risers with a 280 mm going
  3. 15 risers with a 320 mm going
  4. 22 risers with a 250 mm going

Explanation

A 3.0 m rise divided by 150 mm gives 20 risers. Applying 2R + G = 600 mm with R = 150 mm gives G = 300 mm, a comfortable going. The other combinations do not match the total rise or the proportion rule consistently.

Question 48Building Construction Techniques and Components

Which defect in brickwork is described as a vertical crack that follows the junction between two lifts of masonry placed on different days?

  1. Efflorescence
  2. Segregation
  3. Shrinkage crack at a construction joint Correct answer.
  4. Blistering

Explanation

When masonry is built in lifts and the next lift is placed later, the earlier bed may have taken initial set, producing a weak plane; shrinkage and movement then open a vertical or horizontal crack along that construction joint. Efflorescence is a salt deposit, blistering is a plaster defect, and segregation concerns concrete mixing.

Question 49Building Construction Techniques and Components

A concrete mix is specified as M20 with a water-cement ratio of 0.50. If 50 kg of cement is used per batch, what is the approximate quantity of water required?

  1. 50 litres
  2. 15 litres
  3. 25 litres Correct answer.
  4. 40 litres

Explanation

Water-cement ratio is the mass of water divided by the mass of cement, so 0.50 x 50 kg gives 25 kg of water, which is approximately 25 litres since 1 litre of water weighs about 1 kg. The other values correspond to ratios of 0.3, 0.8 and 1.0, which are outside the specification.

Question 50Building Construction Techniques and Components

A two-leaf cavity wall shows dampness on the inner leaf after driving rain. Which cause is most likely, given that the cavity is clear and ties are correctly installed?

  1. The wall has weep holes at the base
  2. The DPC at plinth level is continuous
  3. Rainwater is bridging the cavity through mortar droppings on wall ties Correct answer.
  4. The inner leaf is thicker than the outer leaf

Explanation

Mortar droppings that collect on wall ties form a bridge across the cavity, allowing rainwater to travel from the saturated outer leaf to the inner leaf. A continuous DPC and correctly placed weep holes are protective features, not causes. Differences in leaf thickness do not by themselves transfer water across the cavity.