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Punjab PSEB Matric NSQF Construction study materials
Punjab PSEB Matric NSQF Construction study resources

Punjab PSEB Matric NSQF Construction practice questions

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Question 1NSQF Vocational Trade Theory (Construction)

In NSQF construction trade practice, which tool is used to check whether a masonry wall is perfectly vertical?

  1. Spirit level
  2. Steel tape
  3. Try square
  4. Plumb bob Correct answer.

Explanation

A plumb bob hangs on a cord and its line points exactly to the centre of gravity, so it indicates true verticality over the full height of a wall. A spirit level checks level and plumb over the length of its own body only, so it is not the tool named for checking verticality of a tall wall.

Question 2NSQF Vocational Trade Theory (Construction)

Which of the following is the correct nominal mix proportion by volume for M15 grade concrete as per common Indian practice?

  1. 1:4:8
  2. 1:1:2
  3. 1:2:4 Correct answer.
  4. 1:3:6

Explanation

M15 concrete is commonly produced with a nominal volume mix of 1 part cement, 2 parts fine aggregate and 4 parts coarse aggregate. The other proportions correspond to different grades such as M25, M10 and M7.5 respectively.

Question 3NSQF Vocational Trade Theory (Construction)

A mortar mix of 1:6 means one part cement to six parts of which material by volume?

  1. Coarse aggregate
  2. Water
  3. Lime
  4. Sand (fine aggregate) Correct answer.

Explanation

In cement mortar notation the second figure always refers to fine aggregate, that is sand, measured by volume. Coarse aggregate is not used in mortar, lime is a separate binding material, and water is added by workability requirement, not as a mix ratio component.

Question 4NSQF Vocational Trade Theory (Construction)

Which bond in brick masonry consists of alternate courses of headers and stretchers, giving good strength and appearance?

  1. Flemish bond
  2. Header bond
  3. English bond Correct answer.
  4. Stretcher bond

Explanation

English bond places one course of headers between successive courses of stretchers, which produces strong, well-keyed masonry. Flemish bond alternates header and stretcher within the same course, stretcher bond uses only stretchers, and header bond uses only headers.

Question 5NSQF Vocational Trade Theory (Construction)

In building drawing practice, a dimension of 1:50 on a plan means that one unit on the drawing represents what on the ground?

  1. 500 units
  2. 5 units
  3. 50 units Correct answer.
  4. 0.5 units

Explanation

A scale of 1:50 is a reducing scale in which one drawing unit equals fifty real units, so 20 mm on paper represents 1000 mm on site. The other values misread the ratio as 1:5, 1:500 or 1:0.5.

Question 6NSQF Vocational Trade Theory (Construction)

Which safety practice is mandatory before starting excavation for a foundation in a construction site?

  1. Checking for underground electric cables and services Correct answer.
  2. Removing shoring from an adjacent pit
  3. Stacking excavated soil against the pit edge
  4. Allowing water to collect in the pit

Explanation

Before digging, the site must be checked for buried services such as cables, water lines and gas pipes so that they are isolated or diverted. Stacking spoil at the edge adds surcharge that can collapse the sides, and standing water or removed shoring increases collapse risk.

Question 7NSQF Vocational Trade Theory (Construction)

Which of these is the standard curing period normally recommended for ordinary Portland cement concrete to reach adequate strength?

  1. 60 days
  2. 1 day
  3. 3 days
  4. 7 to 14 days Correct answer.

Explanation

Concrete is normally kept moist for at least 7 days for ordinary cement and up to 14 days for important or hot-weather work, because curing water is needed for continued hydration. One or three days is too short for adequate strength gain, and sixty days is far beyond normal practice.

Question 8NSQF Vocational Trade Theory (Construction)

Which material is classified as a coarse aggregate in concrete production?

  1. Cement
  2. Stone dust passing 75 micron
  3. Crushed stone of 20 mm size Correct answer.
  4. River sand

Explanation

Coarse aggregate is the fraction retained on the 4.75 mm sieve, typically crushed stone of 20 mm nominal size. River sand and fine stone dust are fine aggregates, while cement is the binder.

Question 9NSQF Vocational Trade Theory (Construction)

A mason needs to lay a course of bricks so that every brick is level and the joints are of uniform thickness. Which combination of tools is most appropriate?

  1. Plumb bob and try square
  2. Bolt and chisel
  3. Mallet and crowbar
  4. Spirit level and trowel Correct answer.

Explanation

A spirit level is used to check that each brick course is horizontal, and a mason's trowel is used to spread mortar to a uniform bed and thickness. The other combinations serve verticality, timber working or demolition tasks rather than levelling a course.

Question 10NSQF Vocational Trade Theory (Construction)

In a brick masonry wall, why are bricks soaked in water before laying?

  1. To improve their colour
  2. To make them easier to break
  3. To increase their weight
  4. To prevent them absorbing water from the mortar Correct answer.

Explanation

Dry bricks absorb water from the mortar, which stops the cement from hydrating properly and weakens the joint. Soaking the bricks beforehand keeps the mortar moist so that it sets with full strength. Weight, breakability and colour are not reasons for soaking.

Question 11NSQF Vocational Trade Theory (Construction)

A concrete mix has a cement:sand:aggregate ratio of 1:2:4 by volume and the cement content is 50 kg. What is the volume of sand required?

  1. 25 kg
  2. 100 kg Correct answer.
  3. 50 kg
  4. 200 kg

Explanation

The ratio 1:2:4 means sand is twice the cement quantity by volume, so 50 kg of cement needs 2 x 50 = 100 kg of sand. The other values correspond to half, one and four times the cement quantity.

Question 12NSQF Vocational Trade Theory (Construction)

Which test is used to determine the workability of fresh concrete on site?

  1. Slump test Correct answer.
  2. Cube crushing test
  3. Sieve analysis
  4. Vicat needle test

Explanation

The slump test measures the consistency and hence workability of fresh concrete by the settlement of a cone of concrete. Cube crushing measures hardened strength, sieve analysis measures grading of aggregates, and the Vicat needle measures setting time of cement.

Question 13NSQF Vocational Trade Theory (Construction)

In a plan drawn to a scale of 1:100, a wall measures 45 mm on the drawing. What is its actual length?

  1. 4.5 m Correct answer.
  2. 45 m
  3. 450 m
  4. 0.45 m

Explanation

At 1:100, each millimetre on the drawing equals 100 mm on site, so 45 mm represents 4500 mm, that is 4.5 m. The other answers result from misplacing the decimal point in the conversion.

Question 14NSQF Vocational Trade Theory (Construction)

Which type of foundation is generally suitable for a multi-storey building on soft soil where shallow foundations would settle excessively?

  1. Isolated footing
  2. Raft foundation Correct answer.
  3. Random rubble footing
  4. Strip footing

Explanation

A raft foundation spreads the building load over the whole footprint, reducing contact pressure and differential settlement on soft or weak soil. Isolated and strip footings concentrate load over a small area, and rubble footing is a traditional shallow option for load-bearing walls.

Question 15NSQF Vocational Trade Theory (Construction)

Which of the following is the main purpose of providing a damp-proof course (DPC) at plinth level in a building?

  1. To stop moisture rising from the ground into the walls Correct answer.
  2. To carry the load of the superstructure
  3. To increase the height of the plinth
  4. To provide a bond between brick courses

Explanation

A DPC is an impervious layer at plinth level that blocks capillary rise of groundwater into the walls, preventing dampness and efflorescence. It does not carry structural load, increase plinth height or act as a bonding course.

Question 16NSQF Vocational Trade Theory (Construction)

While plastering an internal wall, which sequence gives the best finish?

  1. Apply plaster only at the top and let gravity spread it
  2. Apply a thin first coat, roughen it, then apply the finishing coat and float it Correct answer.
  3. Apply plaster before fixing conduits and then chase the wall
  4. Apply thick coat in one pass, then smooth with a float

Explanation

Plastering is done in coats: a thinner undercoat is applied and its surface roughened to give a key, then the finishing coat is applied and floated to a smooth surface. A single thick coat shrinks and cracks, and conduits must be fixed before plastering.

Question 17NSQF Vocational Trade Theory (Construction)

Which property of cement is indicated by its initial setting time of not less than 30 minutes for ordinary Portland cement?

  1. The time available for mixing, placing and compacting the concrete Correct answer.
  2. The time after which the concrete must be cured
  3. The time taken for the cement to be ground
  4. The time required for full strength development

Explanation

The initial setting time marks the start of stiffening, so it must be long enough to allow mixing, transporting, placing and compacting of the concrete. Full strength develops over weeks of curing, and grinding is a manufacturing step unrelated to setting time.

Question 18NSQF Vocational Trade Theory (Construction)

A mason is asked to build a half-brick (115 mm) partition wall. Which bond is most suitable?

  1. Flemish bond
  2. Header bond
  3. Stretcher bond Correct answer.
  4. English bond

Explanation

A half-brick wall has a thickness equal to one brick lengthwise, so all bricks are laid as stretchers in stretcher bond. English, Flemish and header bonds need at least one full brick thickness or more to develop their header-stretcher pattern.

Question 19NSQF Vocational Trade Theory (Construction)

Which of the following correctly states the purpose of a lean concrete (PCC) layer below a footing?

  1. To improve the appearance of the foundation
  2. To increase the depth of the footing
  3. To act as a substitute for reinforcement
  4. To provide a level, clean base and prevent soil from absorbing water from the structural concrete Correct answer.

Explanation

A PCC layer provides a firm, level working surface, keeps the soil from sucking water out of the footing concrete and prevents dirt from mixing with it. It is not a structural substitute for reinforcement and has no role in appearance or depth.

Question 20NSQF Vocational Trade Theory (Construction)

A worker must cut a 20 mm diameter steel reinforcement bar on site. Which tool is most appropriate for a clean, quick cut?

  1. Hacksaw with a fine blade
  2. Cold chisel and mallet
  3. Wood saw
  4. Bar bending and cutting machine Correct answer.

Explanation

A bar cutting machine is designed to shear reinforcement bars quickly and squarely, which is important for correct anchorage and bending. A hacksaw is slow for 20 mm bars, a wood saw cannot cut steel, and a chisel and mallet would deform the bar.

Question 21NSQF Vocational Trade Theory (Construction)

In reinforced concrete, why is a concrete cover of at least 40 mm normally specified for a footing exposed to soil?

  1. To protect the reinforcement from corrosion and to ensure bond with concrete Correct answer.
  2. To make the footing easier to paint
  3. To allow more reinforcement to be placed
  4. To reduce the weight of the footing

Explanation

Adequate cover keeps soil moisture and chemicals away from the steel so that it does not corrode, and it also provides enough concrete around the bar for bond and fire resistance. Cover does not reduce weight, improve paintability or permit extra steel.

Question 22NSQF Vocational Trade Theory (Construction)

Which sequence of operations is correct when constructing a load-bearing brick wall?

  1. Marking and leveling, laying first course with mortar, checking plumb and level at each course, raking joints and curing Correct answer.
  2. Painting the wall after the first course
  3. Laying all courses first, then checking plumb at the end
  4. Curing the wall before laying any course

Explanation

Work starts with setting out and levelling the base, then each course is laid in mortar and checked for plumb and level before the next course is added. Final checking after all courses is too late, curing comes after construction, and painting is a finishing operation.

Question 23NSQF Vocational Trade Theory (Construction)

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

  1. 36 N/mm²
  2. 54 N/mm²
  3. 24 N/mm² Correct answer.
  4. 12 N/mm²

Explanation

Compressive strength equals load divided by the loaded area, that is 540000 N divided by 22500 mm², giving 24 N/mm². The other values result from dividing by the wrong area or by the cube side only.

Question 24NSQF Vocational Trade Theory (Construction)

A site engineer finds that a batch of concrete has a slump of 180 mm although the specified slump is 50 mm. Which action is most appropriate?

  1. Add cement and coarse aggregate to the batch to correct the water-cement ratio and re-test the slump Correct answer.
  2. Add only sand to stiffen the mix
  3. Add more water to make it easier to place
  4. Place the concrete as it is because higher slump means stronger concrete

Explanation

Excess slump means too much water relative to cement, which lowers strength; adding cement and aggregate restores the water-cement ratio. Adding more water worsens the problem, high slump does not mean high strength, and adding only sand distorts the aggregate grading.

Question 25NSQF Vocational Trade Theory (Construction)

In a two-room building, a 230 mm brick wall is to be built over a 1.2 m wide opening in a load-bearing wall. Which structural element is provided directly above the opening?

  1. Damp-proof course
  2. Plinth beam
  3. Raft
  4. Lintel Correct answer.

Explanation

A lintel is a horizontal member placed over an opening to carry the masonry above it and transfer the load to the sides. A plinth beam is at plinth level, a DPC is an impervious layer, and a raft is a foundation type.

Question 26NSQF Vocational Trade Theory (Construction)

In construction work, which personal protective equipment is specifically required while handling cement bags and mixing mortar?

  1. Ear plugs and welding shield
  2. Face shield and rubber apron only
  3. Life jacket and safety harness
  4. Dust mask, gloves and safety goggles Correct answer.

Explanation

Cement dust irritates the respiratory tract and wet cement is alkaline enough to burn skin, so a dust mask, gloves and goggles are the standard protection for bag handling and mortar mixing. Other items listed belong to welding, working at height or water work and do not address cement hazards.

Question 27NSQF Vocational Trade Theory (Construction)

A mason has to check that a brick is of good quality before it is used in a load-bearing wall. Which simple field test gives a quick indication of good burning and strength?

  1. Dropping the brick from a height of 2 m
  2. Striking two bricks together and listening for a clear metallic ring Correct answer.
  3. Immersing the brick in kerosene for 24 hours
  4. Weighing the brick on a spring balance

Explanation

A well-burnt brick gives a clear ringing sound when struck against another brick, while a dull thud suggests under-burning or internal cracks. This field test is quick, needs no apparatus and is widely used on site to judge burning quality.

Question 28NSQF Vocational Trade Theory (Construction)

Which type of lime is produced by burning limestone and then slaking it, and is commonly used for making lime mortar and whitewash on site?

  1. Hydraulic lime
  2. Kankar lime
  3. Quick lime
  4. Fat lime (hydrated lime) Correct answer.

Explanation

Fat lime, also called hydrated lime, is obtained by slaking quick lime and is highly plastic, so it is used for mortar, plaster and whitewash. Quick lime is the unslaked product, hydraulic lime sets under water, and kankar lime is a naturally occurring impure lime.

Question 29NSQF Vocational Trade Theory (Construction)

Which statement correctly describes the purpose of a plumb bob used by a mason?

  1. To check that a wall face is truly vertical Correct answer.
  2. To check that a course of bricks is horizontal
  3. To test the hardness of the brick surface
  4. To measure the thickness of mortar joints

Explanation

A plumb bob hangs on a string and, when the string is held against the wall face, shows whether the surface is truly vertical. Horizontal levelling is checked with a spirit level, and joint thickness is measured with a tape or rod.

Question 30NSQF Vocational Trade Theory (Construction)

Which of the following is a standard size of a modular clay brick as used in Indian construction practice?

  1. 250 mm x 125 mm x 75 mm
  2. 300 mm x 150 mm x 100 mm
  3. 230 mm x 110 mm x 70 mm
  4. 190 mm x 90 mm x 90 mm Correct answer.

Explanation

The modular brick has a nominal size of 200 mm x 100 mm x 100 mm, giving an actual size of 190 mm x 90 mm x 90 mm so that a 10 mm joint brings it back to the nominal module. The 230 mm x 110 mm x 70 mm size is the traditional non-modular brick.

Question 31NSQF Vocational Trade Theory (Construction)

A mason is told to build a 230 mm thick wall using bricks of 230 mm x 110 mm x 70 mm. Which bond will give the strongest wall with proper interlocking of headers and stretchers?

  1. English bond Correct answer.
  2. Stretcher bond
  3. Flemish bond
  4. Stack bond

Explanation

English bond alternates a course of headers with a course of stretchers, giving strong longitudinal and transverse interlocking, which makes it the strongest bond for one-brick walls. Stretcher bond is used for half-brick walls, Flemish bond is decorative, and stack bond has no interlocking.

Question 32NSQF Vocational Trade Theory (Construction)

Which statement correctly describes the function of a lintel in a building?

  1. It ties the two leaves of a cavity wall together.
  2. It provides a horizontal surface for fixing floor tiles.
  3. It distributes the load of a wall over a wider area of soil.
  4. It carries the load of the wall above an opening such as a door or window. Correct answer.

Explanation

A lintel is a horizontal member placed over a door or window opening to support the masonry above it and transfer that load to the adjacent wall. Load spreading over soil is the job of a footing, and cavity ties are separate components.

Question 33NSQF Vocational Trade Theory (Construction)

Which material is commonly used as a damp-proof course (DPC) at plinth level in a load-bearing brick wall?

  1. Ordinary burnt clay brick
  2. Sand filling of 100 mm depth
  3. Polythene sheet of about 400 micron thickness Correct answer.
  4. Cement mortar of 1:6 mix

Explanation

A flexible impervious material such as a 400 micron polythene sheet is laid across the full wall thickness at plinth level to stop rising damp. Bricks, mortar and sand are all porous and would allow moisture to travel up the wall.

Question 34NSQF Vocational Trade Theory (Construction)

In a concrete mix, a supervisor adds extra water on site to make placing easier. Which property of the hardened concrete is most directly reduced by this practice?

  1. Compressive strength Correct answer.
  2. Colour uniformity
  3. Unit weight of cement
  4. Initial setting time of cement

Explanation

Extra water increases the water-cement ratio, which raises porosity and directly lowers the compressive strength of hardened concrete. Colour, cement unit weight and the setting time of cement are not the main properties affected by the added water.

Question 35NSQF Vocational Trade Theory (Construction)

A concrete cube of 150 mm side is tested and fails at a load of 450 kN. What is the compressive strength of the concrete?

  1. 15 N/mm2
  2. 30 N/mm2
  3. 45 N/mm2
  4. 20 N/mm2 Correct answer.

Explanation

The loaded area is 150 mm x 150 mm = 22500 mm2, and strength equals load divided by area, so 450000 N / 22500 mm2 = 20 N/mm2. This equals 20 MPa, a typical value for M20 concrete.

Question 36NSQF Vocational Trade Theory (Construction)

A slump test on a concrete batch gives a true slump of 25 mm, but the specification requires 50 mm to 75 mm for the intended placement. Which action is most appropriate?

  1. Add a suitable water-reducing admixture or adjust the water content under supervision Correct answer.
  2. Increase the mixing time only
  3. Add more cement without changing the water
  4. Add more coarse aggregate to stiffen the mix

Explanation

Low workability means the mix is too stiff for placement, and the correct response is to adjust the water content or use a water-reducing admixture while keeping the water-cement ratio within limits and with engineer approval. Adding aggregate or cement alone changes the mix proportions and does not reliably correct workability.

Question 37NSQF Vocational Trade Theory (Construction)

A masonry wall has to be raised in a single day. Which practice helps to avoid loss of plumb and uneven courses?

  1. Raising the wall in lifts of about 1 m with a line and level check at each lift Correct answer.
  2. Laying bricks without soaking them to save time
  3. Raising the full height of the wall in one continuous stretch
  4. Using a richer mortar to speed up laying

Explanation

Raising masonry in lifts of about 1 m allows the mortar to gain some strength and lets the mason check line, level and plumb at each stage, so errors do not accumulate. Building the full height at once causes bulging and loss of alignment before the mortar sets.

Question 38NSQF Vocational Trade Theory (Construction)

A wall of a room measures 4.0 m long and 3.0 m high, with a door opening of 1.0 m x 2.1 m. Using a 230 mm thick wall, what is the approximate volume of brickwork, ignoring mortar deductions for small openings?

  1. 2.28 m3 Correct answer.
  2. 3.60 m3
  3. 2.76 m3
  4. 3.28 m3

Explanation

The gross wall area is 4.0 x 3.0 = 12.0 m2, and the door opening is 1.0 x 2.1 = 2.1 m2, leaving a net area of 9.9 m2. Multiplying by the thickness of 0.23 m gives about 2.28 m3 of brickwork.

Question 39NSQF Vocational Trade Theory (Construction)

Which type of foundation is generally chosen when a load-bearing wall has to be founded on soil of low bearing capacity at shallow depth?

  1. Pile cap without piles
  2. Strip footing widened at the base Correct answer.
  3. Raft foundation only
  4. Isolated footing

Explanation

A strip footing runs continuously under a load-bearing wall and can be widened at the base to spread the load over a larger soil area where bearing capacity is low. Isolated footings suit columns, and a pile cap without piles is not a foundation at all.

Question 40NSQF Vocational Trade Theory (Construction)

A mason has to plaster an external wall that will be exposed to rain. Which mix and finish is most suitable?

  1. 1:3 cement mortar with a glossy paint finish only
  2. 1:4 cement mortar with a slightly rough texture finish Correct answer.
  3. 1:6 cement mortar with a smooth trowel finish
  4. 1:8 lime mortar with a polished finish

Explanation

A richer 1:4 cement mortar gives better weather resistance, and a slightly rough texture helps shed water and improves key for any subsequent treatment. Very lean mixes or smooth polished surfaces are more prone to cracking and crazing under rain exposure.

Question 41NSQF Vocational Trade Theory (Construction)

Which statement correctly explains why reinforcement bars are provided with a specified concrete cover in reinforced concrete work?

  1. To make the concrete easier to compact around the formwork
  2. To increase the workability of the fresh concrete
  3. To protect the steel from corrosion and provide fire resistance and bond Correct answer.
  4. To reduce the quantity of steel required in the member

Explanation

Concrete cover forms an alkaline protective layer around the steel, prevents moisture and oxygen reaching it, provides fire resistance and helps the bond between steel and concrete. It does not reduce steel quantity or change workability.

Question 42NSQF Vocational Trade Theory (Construction)

A steel bar is to be bent into a hook on site. Which equipment is most suitable for bending bars up to 20 mm diameter accurately and repeatedly?

  1. Wooden mallet
  2. Bar bending machine with a bending table Correct answer.
  3. Hack saw
  4. Bolt cutter

Explanation

A bar bending machine with a bending table gives controlled, repeatable bends to the required angle and radius for reinforcement work. A hacksaw cuts rather than bends, a bolt cutter is for cutting, and a mallet cannot bend steel bars.

Question 43NSQF Vocational Trade Theory (Construction)

Which sequence is correct for preparing a reinforced concrete beam on site before placing concrete?

  1. Erect formwork, fix reinforcement with cover blocks, then place and compact concrete Correct answer.
  2. Erect formwork, place concrete, then insert reinforcement
  3. Place concrete, then fix reinforcement, then erect formwork
  4. Fix reinforcement, place concrete, then erect formwork

Explanation

Formwork is erected first to give shape, reinforcement is then fixed with cover blocks to maintain the specified cover, and finally concrete is placed and compacted. Placing concrete before reinforcement or formwork would make correct positioning impossible.

Question 44NSQF Vocational Trade Theory (Construction)

A plan shows a room 30 mm long on paper at a scale of 1:50. What is the actual length of the room?

  1. 150 m
  2. 1.5 m Correct answer.
  3. 15 m
  4. 0.6 m

Explanation

At a scale of 1:50, one unit on the drawing represents 50 units on the ground, so 30 mm on paper equals 30 x 50 = 1500 mm, or 1.5 m. This is a typical room length and confirms the calculation.

Question 45NSQF Vocational Trade Theory (Construction)

A mason is laying a half-brick partition wall 115 mm thick. Which bond and practice is most appropriate?

  1. Flemish bond with every course showing headers
  2. Raking bond with inclined bricks
  3. Stretcher bond with header bricks at intervals and at junctions Correct answer.
  4. English bond with alternate header courses

Explanation

A half-brick wall is normally built in stretcher bond, but header bricks are introduced at intervals and at junctions with cross walls to tie the leaves and stiffen the wall. English and Flemish bonds need a full brick thickness, and raking bond is not used for partitions.

Question 46NSQF Vocational Trade Theory (Construction)

A concrete mix is specified as M20. What does the designation M20 indicate?

  1. A mix with 20 kg of cement per bag
  2. A mix with a maximum aggregate size of 20 mm
  3. A concrete with a slump of 20 mm
  4. A concrete with a characteristic compressive strength of 20 N/mm2 at 28 days Correct answer.

Explanation

The grade M20 denotes concrete with a characteristic cube compressive strength of 20 N/mm2 at 28 days, tested on standard cubes. It does not refer to cement quantity, slump or aggregate size.

Question 47NSQF Vocational Trade Theory (Construction)

A site has to build a 230 mm load-bearing wall over a 2 m wide opening. Which structural arrangement is most suitable for supporting the wall above the opening?

  1. A course of bricks laid in stretcher bond across the opening
  2. A single 70 mm thick brick on edge
  3. A reinforced concrete lintel bearing at least 150 mm on each side Correct answer.
  4. A timber plank spanning the opening

Explanation

For a 2 m span carrying wall load, a reinforced concrete lintel with adequate bearing of at least 150 mm on each side is required to transfer the load safely to the masonry. A brick on edge, timber plank or plain brick course cannot carry the load over such a span.

Question 48NSQF Vocational Trade Theory (Construction)

A brick masonry wall shows a long diagonal crack running from the corner of a window towards the roof. Which is the most likely cause?

  1. Differential settlement of the foundation or lack of a lintel bearing Correct answer.
  2. Use of a plumb bob during construction
  3. Curing of masonry for seven days
  4. Excess soaking of bricks before laying

Explanation

Diagonal cracks radiating from opening corners are a classic sign of differential settlement or of inadequate lintel support allowing stress concentration at the opening. Curing, soaking and use of a plumb bob do not cause such cracking.

Question 49NSQF Vocational Trade Theory (Construction)

A concrete cube test result at 28 days is 18 N/mm2 for a mix designed as M20. Which interpretation and action is most appropriate?

  1. Accept the concrete because 18 N/mm2 is close to 20 N/mm2
  2. Investigate with non-destructive tests or core tests before taking a decision Correct answer.
  3. Increase the cement content of future batches only
  4. Reject the result without further testing and demolish the member

Explanation

A single cube failing the characteristic strength does not by itself prove the structure is unsafe, so further investigation by rebound hammer, ultrasonic or core testing is needed before acceptance or rejection. Demolition without investigation is premature, and accepting a shortfall without check is equally wrong.

Question 50NSQF Vocational Trade Theory (Construction)

A masonry pier is to be built to carry a concentrated load in a load-bearing wall. Which detail most improves its load-carrying capacity?

  1. Using a hollow clay block pier without filling
  2. Reducing the mortar joint thickness to 2 mm
  3. Attaching the pier to the wall with toothed bonding and providing a wider base Correct answer.
  4. Building the pier with the same bond as the wall and no connection

Explanation

A pier gains strength when it is properly bonded into the wall by toothing and is widened at the base to spread the load over a larger area. An unbonded pier can separate from the wall, and very thin joints cannot be achieved with normal bricks and reduce bond.