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Odisha CHSE +2 Vocational Building Maintenance study materials
Odisha CHSE +2 Vocational Building Maintenance study resources

Odisha CHSE +2 Vocational Building Maintenance practice questions

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Question 1Building Materials and Construction Basics

In building construction, which material is obtained by burning clay in a kiln and is commonly used for walls and roofing in Odisha?

  1. Mild steel
  2. Glass
  3. Portland cement
  4. Burnt brick Correct answer.

Explanation

Burnt bricks are made by moulding clay, drying it, and firing it in a kiln until it hardens. The firing gives strength, low water absorption and good durability, which is why burnt bricks are widely used for walls and roofing in Odisha. Cement, steel and glass are manufactured by entirely different processes.

Question 2Building Materials and Construction Basics

Which of the following is the correct standard size of a modular burnt clay brick used in Indian building work?

  1. 230 mm × 110 mm × 75 mm
  2. 190 mm × 90 mm × 90 mm Correct answer.
  3. 300 mm × 150 mm × 100 mm
  4. 250 mm × 125 mm × 65 mm

Explanation

The modular brick has nominal dimensions of 200 mm × 100 mm × 100 mm, and its actual or modular size is 190 mm × 90 mm × 90 mm. The 10 mm allowance on each dimension accounts for the mortar joint, so the brick plus joint forms a neat module. The other sets of dimensions do not match the modular system.

Question 3Building Materials and Construction Basics

A first-class brick, when struck with another brick or a hammer, should produce which type of sound?

  1. A soft muffled sound
  2. A dull thud
  3. No sound at all
  4. A clear metallic ringing sound Correct answer.

Explanation

A clear ringing or metallic sound on striking indicates that the brick is well burnt, dense and free from internal cracks. A dull thud suggests under-burning, cracks or excessive voids. This simple field test is part of the standard inspection of bricks on site.

Question 4Building Materials and Construction Basics

Which ingredient in ordinary Portland cement is mainly responsible for the quick initial setting and early strength development?

  1. Tetracalcium aluminoferrite
  2. Dicalcium silicate
  3. Tricalcium aluminate Correct answer.
  4. Tricalcium silicate

Explanation

Tricalcium aluminate reacts very rapidly with water and controls the initial set, which is why gypsum is added to retard it. Tricalcium silicate gives most of the early strength, while dicalcium silicate contributes mainly to long-term strength. Tetracalcium aluminoferrite has a comparatively minor role.

Question 5Building Materials and Construction Basics

In the field, the soundness of cement is tested to detect which defect?

  1. Insufficient compressive strength at 28 days
  2. Excessive fineness of grinding
  3. Presence of excess gypsum causing flash set
  4. Expansion after setting due to uncombined lime or magnesia Correct answer.

Explanation

The soundness test, commonly done with the Le Chatelier apparatus, detects delayed expansion caused by free lime or magnesia that hydrates after the cement has set. Such expansion cracks or distorts hardened concrete. Fineness, strength and setting time are checked by separate tests.

Question 6Building Materials and Construction Basics

Why is a small quantity of gypsum added during the manufacture of Portland cement?

  1. To reduce the cost of the finished cement
  2. To improve the colour of the cement powder
  3. To retard the setting action of the cement Correct answer.
  4. To increase the compressive strength of concrete

Explanation

Without gypsum, tricalcium aluminate reacts with water so fast that the cement would stiffen within minutes, a condition called flash set. Gypsum acts as a set regulator and gives the worker enough time to place and compact the concrete. It does not act as a strength-giving compound.

Question 7Building Materials and Construction Basics

Which of the following is classified as a coarse aggregate in ordinary concrete work?

  1. Lime powder used as a filler
  2. Crushed stone retained on a 4.75 mm sieve Correct answer.
  3. Stone dust passing a 150 micron sieve
  4. River sand passing a 4.75 mm sieve

Explanation

Aggregates retained on the 4.75 mm sieve are coarse aggregates, such as crushed stone or gravel. Material passing the 4.75 mm sieve is fine aggregate, such as river sand. The distinction matters because coarse aggregate forms the skeleton of concrete while fine aggregate fills the voids.

Question 8Building Materials and Construction Basics

In a concrete mix designated M20, what does the number 20 represent?

  1. The characteristic compressive strength in N/mm² at 28 days Correct answer.
  2. The maximum size of coarse aggregate in millimetres
  3. The slump value in millimetres
  4. The cement content in bags per cubic metre

Explanation

In the M-grade system, M stands for mix and the number gives the characteristic cube compressive strength at 28 days in N/mm². Thus M20 concrete is expected to reach 20 N/mm² on 150 mm cubes at 28 days. Aggregate size and workability are specified separately.

Question 9Building Materials and Construction Basics

A concrete mix has a cement:sand:aggregate proportion of 1:2:4 by volume. What grade of concrete does this nominal mix correspond to?

  1. M20 Correct answer.
  2. M10
  3. M5
  4. M15

Explanation

The nominal mix 1:2:4 is the standard volumetric proportion for M20 grade concrete. The richer mixes 1:1:2 and 1:1.5:3 correspond to M25 and M20 respectively in some tables, while 1:3:6 and 1:4:8 give lower grades. For ordinary reinforced work 1:2:4 is a common specification.

Question 10Building Materials and Construction Basics

During a slump test on a concrete sample, the cone settles by 25 mm. How is this result best described?

  1. A stiff mix with very low workability
  2. A mix of medium workability
  3. A high-workability mix suitable for pumping
  4. A mix of low workability Correct answer.

Explanation

For the standard slump cone, a slump of about 25 to 75 mm is generally classed as low workability. Very low slumps near zero indicate a stiff mix, while slumps above about 100 mm indicate medium to high workability. The measured value therefore places this concrete in the low range.

Question 11Building Materials and Construction Basics

Which test is used to determine the workability of concrete by measuring the time taken for a given vibration to remould a sample?

  1. Slump test
  2. Vee-Bee consistometer test Correct answer.
  3. Compaction factor test
  4. Cube crushing test

Explanation

The Vee-Bee consistometer measures the time in seconds needed for a concrete sample to be remoulded from a cone shape into a cylinder under vibration. This time is a measure of workability and suits very stiff mixes. The compaction factor test uses a different principle, and the cube test measures strength.

Question 12Building Materials and Construction Basics

Why is curing of concrete necessary after it has been placed and finished?

  1. To keep the concrete moist so that hydration and strength gain can continue Correct answer.
  2. To increase the water content of the mix
  3. To speed up the evaporation of mixing water
  4. To remove excess cement from the surface

Explanation

Cement gains strength through hydration, which requires water. If the concrete dries out too early, hydration stops and the surface becomes weak, porous and prone to cracking. Curing keeps the concrete moist for the required period so that strength and durability develop properly.

Question 13Building Materials and Construction Basics

In brick masonry, which bond is formed by placing bricks alternately as headers and stretchers in the same course?

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

Explanation

Flemish bond alternates a header and a stretcher within each course, giving a strong and attractive wall face. English bond instead uses separate courses of headers and stretchers. Stretcher bond shows only stretchers, and header bond shows only headers.

Question 14Building Materials and Construction Basics

What is the main purpose of providing a mortar joint of about 10 mm thickness between bricks in masonry?

  1. To permit thermal expansion of each brick
  2. To bind the bricks together and distribute the load evenly Correct answer.
  3. To reduce the overall height of the wall
  4. To allow water to drain through the wall

Explanation

Mortar acts as a bedding material that bonds the units into a single structural mass and spreads the load over a larger area, avoiding stress concentration. The joint thickness is kept uniform so that the load transfer is even. A joint that is too thick weakens the masonry, and one that is too thin cannot bond properly.

Question 15Building Materials and Construction Basics

Which mortar is prepared by mixing cement, sand and lime and is known for good workability and water retention?

  1. Cement-lime mortar Correct answer.
  2. Mud mortar
  3. Cement mortar
  4. Lime mortar

Explanation

Cement-lime mortar, also called composite or gauged mortar, combines the strength of cement with the plasticity and water retention of lime. The lime makes the mix easier to spread and reduces shrinkage cracking. Plain cement mortar is stronger but harsher, and mud mortar is weak and not water-resistant.

Question 16Building Materials and Construction Basics

Which type of foundation is most suitable for a load-bearing masonry wall of a small two-storey building on firm soil?

  1. Well foundation
  2. Pile foundation
  3. Strip footing Correct answer.
  4. Raft foundation

Explanation

A strip footing is a continuous widened base running under a wall and is the usual choice for load-bearing walls on soil of adequate bearing capacity. It spreads the wall load over a sufficient area at shallow depth. Rafts, piles and wells are used for heavier loads or poor soil conditions.

Question 17Building Materials and Construction Basics

What is the main function of a damp-proof course provided near the plinth level of a building?

  1. To provide a level surface for flooring
  2. To prevent moisture from rising into the walls by capillary action Correct answer.
  3. To anchor the doors and windows to the wall
  4. To carry the load of the superstructure

Explanation

A damp-proof course is a continuous impervious layer, such as bitumen or polythene, laid across the wall near plinth level. It blocks the upward movement of groundwater through capillary pores in the masonry. This protects the walls and finishes above from rising damp.

Question 18Building Materials and Construction Basics

A wall is built with a 230 mm thickness using standard bricks laid as stretchers. Which bond is being used?

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

Explanation

When bricks are laid lengthwise along the wall face, the visible face is the stretcher and the wall thickness equals the brick width, about 230 mm including the joint. This is stretcher or running bond, common in half-brick walls. Header bond would show brick ends and produce a similar thickness with a different appearance.

Question 19Building Materials and Construction Basics

Which of the following is the correct sequence of operations in the manufacture of burnt clay bricks by the soft-mud process?

  1. Tempering, moulding, drying, firing Correct answer.
  2. Moulding, firing, tempering, drying
  3. Firing, drying, moulding, tempering
  4. Drying, tempering, firing, moulding

Explanation

In brick manufacture the clay is first tempered with water to make a workable mass, then moulded into shape, dried to remove free moisture, and finally fired in a kiln. Drying before firing is essential because rapid heating of wet bricks causes cracking. Reversing the order would make the bricks weak or distorted.

Question 20Building Materials and Construction Basics

A cement sample gives an initial setting time of 20 minutes and a final setting time of 9 hours. How should this result be interpreted?

  1. The cement is sound and acceptable
  2. Both setting times are within permissible limits
  3. The cement has failed the initial setting time requirement Correct answer.
  4. The cement has failed the final setting time requirement

Explanation

For ordinary Portland cement, the initial setting time should not be less than 30 minutes and the final setting time should not exceed 600 minutes (10 hours). A 20-minute initial set is shorter than the minimum and indicates flash setting, which would make placing and compacting difficult. The final setting time of 9 hours is within limits.

Question 21Building Materials and Construction Basics

Two concrete mixes have water-cement ratios of 0.45 and 0.60, with all other conditions identical. Which statement is most defensible?

  1. The 0.45 mix will generally be stronger and less permeable Correct answer.
  2. The water-cement ratio has no effect on concrete strength
  3. The 0.60 mix will generally be stronger and more durable
  4. Both mixes will reach identical strength at 28 days

Explanation

Abrams' law states that, for a given set of materials, strength decreases as the water-cement ratio increases. A lower ratio of 0.45 leaves less excess water, so the hardened paste has fewer voids and is stronger and less permeable. The 0.60 mix would be more workable but weaker and more porous.

Question 22Building Materials and Construction Basics

In a masonry wall, why are bricks laid with a small overlap over the bricks below rather than stacked directly on top of one another?

  1. To allow rainwater to run down the joints
  2. To make the wall lighter in weight
  3. To avoid continuous vertical joints and thus distribute loads and resist cracking Correct answer.
  4. To reduce the quantity of mortar required

Explanation

Overlapping bricks breaks the continuity of vertical joints, so each brick is supported by the bricks below and the load spreads through the wall. Continuous vertical joints, as in stack bond, act as planes of weakness and allow cracks to develop. The overlap also improves the appearance and stability of the masonry.

Question 23Building Materials and Construction Basics

Which of the following best explains why lime is sometimes added to cement mortar used for plastering?

  1. It makes the mortar waterproof
  2. It speeds up the setting of cement
  3. It improves plasticity and reduces shrinkage cracking Correct answer.
  4. It increases the compressive strength beyond that of plain cement mortar

Explanation

Lime makes the mortar more plastic and easier to spread, and it retains water so that the cement hydrates properly. It also reduces drying shrinkage, which limits hairline cracking in plaster. It does not increase strength or make the mortar waterproof.

Question 24Building Materials and Construction Basics

A building site has a soil with a very low bearing capacity extending to a considerable depth. Which foundation type is most appropriate?

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

Explanation

When the soil is weak over a large depth, a raft foundation spreads the load over the entire building area, reducing contact pressure and differential settlement. Strip and isolated footings would need very large areas and might still settle unevenly. Grillage footings are used for heavy steel columns on firm soil.

Question 25Building Materials and Construction Basics

Which property of a good building stone refers to its ability to withstand weathering without losing strength or appearance?

  1. Porosity
  2. Specific gravity
  3. Durability Correct answer.
  4. Toughness

Explanation

Durability is the resistance of a stone to weathering, abrasion and chemical attack over time, so it retains strength and appearance. Porosity is the proportion of voids, specific gravity is a density measure, and toughness is resistance to impact. A durable stone resists decay in the exposed environment.

Question 26Building Materials and Construction Basics

In building construction, which material is most commonly used as a binding medium in cement mortar for masonry work?

  1. Ordinary Portland cement Correct answer.
  2. Well-graded river sand
  3. Clean potable water
  4. Burnt clay brick bats

Explanation

Cement is the binding material that sets and hardens to hold the fine aggregate particles together into a solid mass. Sand acts only as fine aggregate or filler, brick bats are sometimes used as coarse aggregate in lime concrete, and water is needed for the chemical reaction but does not bind.

Question 27Building Materials and Construction Basics

A standard burnt clay brick used in Indian masonry work is normally expected to have which nominal size?

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

Explanation

The standard modular brick has a nominal face of 200 mm x 100 mm x 100 mm including the mortar joint, which corresponds to an actual brick size of about 190 mm x 90 mm x 90 mm; the traditional field brick is about 230 mm x 110 mm x 70 mm including the joint allowance. The 230 x 110 x 70 figure is the conventional size used in ordinary masonry.

Question 28Building Materials and Construction Basics

Which property of fresh concrete is directly assessed by the compaction factor test?

  1. The rate of heat evolution during hydration
  2. The resistance of concrete to sulphate attack
  3. The compressive strength after 28 days of curing
  4. The workability or ease with which concrete can be compacted Correct answer.

Explanation

The compaction factor test measures the ratio of the weight of concrete compacted under standard falling conditions to the weight of the same concrete fully compacted, which indicates workability. Strength, durability and heat of hydration are separate properties determined by other tests or conditions.

Question 29Building Materials and Construction Basics

In a load-bearing masonry building, what is the main purpose of providing a lintel over a door opening?

  1. To act as a bond between the brick courses
  2. To provide a damp-proof barrier at the plinth
  3. To carry the load of the wall above the opening and transfer it to the sides Correct answer.
  4. To increase the floor area of the room

Explanation

A lintel spans the opening and supports the masonry above it, transferring that load to the adjoining wall portions on either side. It does not create floor area, does not perform damp-proofing, and is not a bonding device between courses.

Question 30Building Materials and Construction Basics

A mason needs mortar for plastering an external wall and wants good workability with improved water retention. Which mortar composition is most appropriate?

  1. Cement, sand and lime in suitable proportions Correct answer.
  2. Cement and coarse aggregate in the ratio 1:2
  3. Cement and sand only, in the ratio 1:3
  4. Lime and sand only, without any cement

Explanation

Adding a small proportion of lime to cement-sand mortar improves workability and water retention, making it easier to spread on the wall and reducing premature drying. Plain cement-sand mortar is harsher to work with, lime-only mortar lacks the strength and setting behaviour of cement, and cement with coarse aggregate is concrete, not plaster mortar.

Question 31Building Materials and Construction Basics

Which type of foundation is generally adopted for a column carrying heavy concentrated loads on soil of moderate bearing capacity?

  1. Grillage foundation
  2. Strip footing
  3. Isolated or spread footing Correct answer.
  4. Raft foundation

Explanation

An isolated footing spreads the load of a single column over a sufficient area of soil and is the usual choice for individual columns. Strip footings serve continuous walls, raft foundations cover the whole area for weak soil, and grillage foundations are used for heavy loads on limited area with steel or timber beams.

Question 32Building Materials and Construction Basics

A concrete mix is to be designed for a water-cement ratio of 0.50. If cement content is 320 kg per cubic metre, what is the approximate water content?

  1. 160 kg Correct answer.
  2. 320 kg
  3. 64 kg
  4. 640 kg

Explanation

The water-cement ratio is the mass of water divided by the mass of cement, so water = 0.50 x 320 kg = 160 kg per cubic metre. The other values arise from misplacing the decimal or from using the cement content directly without applying the ratio.

Question 33Building Materials and Construction Basics

Which of the following is the principal reason for using a mortar joint of controlled thickness in brick masonry?

  1. To distribute the load uniformly and accommodate small size variations of bricks Correct answer.
  2. To allow the bricks to be removed easily later
  3. To prevent the bricks from absorbing any moisture
  4. To increase the self-weight of the wall for stability

Explanation

A controlled mortar joint of about 10 mm provides a uniform bed that distributes loads evenly and absorbs the small dimensional variations of individual bricks. It is not intended for easy dismantling, deliberate weight increase, or making bricks non-absorbent.

Question 34Building Materials and Construction Basics

Which bond in brick masonry is formed by placing bricks alternately as headers and stretchers in the same course, giving a strong and decorative appearance?

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

Explanation

In Flemish bond, each course contains alternating headers and stretchers, which produces a strong wall with an attractive elevation. Stretcher bond uses only stretchers, English bond uses separate header and stretcher courses, and raking bond is a special bond used to fill triangular or irregular areas.

Question 35Building Materials and Construction Basics

A cement sample shows an initial setting time of 45 minutes and a final setting time of 8 hours. How should this result be interpreted against the usual requirements?

  1. Both values are within the normal acceptable limits Correct answer.
  2. The final setting time is too short and the sample is rejected
  3. The initial setting time is too long and the sample is rejected
  4. Both values are outside the acceptable limits and the sample is rejected

Explanation

Ordinary Portland cement should not have an initial setting time earlier than about 30 minutes and a final setting time not later than about 600 minutes (10 hours). A sample setting initially at 45 minutes and finally at 8 hours therefore lies within both limits.

Question 36Building Materials and Construction Basics

Which of the following is the main function of a plinth beam in a framed or load-bearing building?

  1. To carry the staircase flights
  2. To tie the columns or walls at plinth level and distribute loads to the foundation Correct answer.
  3. To serve as a lintel over windows
  4. To support the roof slab directly

Explanation

A plinth beam is provided at plinth level to tie the columns or wall panels together and to distribute the superstructure load more evenly onto the foundation. Roof slabs are supported by beams and columns at roof level, lintels span openings, and staircases have their own supporting members.

Question 37Building Materials and Construction Basics

Which of the following best explains why a damp-proof course is placed continuously across the full width of a wall?

  1. To prevent the upward movement of moisture by capillary action from the foundation Correct answer.
  2. To increase the compressive strength of the wall
  3. To reduce the dead load transferred to the footing
  4. To provide a bond between the foundation concrete and the brickwork

Explanation

A damp-proof course is a continuous impervious layer that interrupts the path of rising damp, preventing moisture from moving upward through the wall by capillary action. It does not add compressive strength, does not act as a bonding layer, and does not reduce the load on the footing.

Question 38Building Materials and Construction Basics

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. 20 N/mm2 Correct answer.
  2. 45 N/mm2
  3. 30 N/mm2
  4. 10 N/mm2

Explanation

The face area of a 150 mm cube is 150 x 150 = 22,500 mm2, and strength equals load divided by area, so 450,000 N / 22,500 mm2 = 20 N/mm2. The other values come from using the side length or the load incorrectly rather than the face area.

Question 39Building Materials and Construction Basics

Which of the following is the primary reason for providing a mortar joint of about 10 mm in brick masonry?

  1. To distribute the load uniformly and accommodate small size variations of bricks Correct answer.
  2. To prevent the bricks from absorbing any moisture
  3. To allow the bricks to be removed easily later
  4. To increase the self-weight of the wall for stability

Explanation

A controlled mortar joint of about 10 mm provides a uniform bed that distributes loads evenly and absorbs the small dimensional variations of individual bricks. It is not intended for easy dismantling, deliberate weight increase, or making bricks non-absorbent.

Question 40Building Materials and Construction Basics

A site has soil of very low bearing capacity extending to a considerable depth. Which foundation type is most suitable for a multi-storey building at that site?

  1. Isolated footings
  2. Raft foundation Correct answer.
  3. Grillage foundation
  4. Strip footing

Explanation

A raft foundation spreads the building load over the entire footprint, reducing the pressure on weak soil and bridging local soft spots. Isolated and strip footings concentrate load on small areas and would settle excessively, while grillage foundations serve heavy concentrated loads on limited areas rather than weak soil over depth.

Question 41Masonry, Plastering and Finishing Works

In brick masonry, the standard thickness of a mortar joint used with modular bricks is normally kept at:

  1. 3 mm
  2. 40 mm
  3. 10 mm Correct answer.
  4. 25 mm

Explanation

Brickwork mortar joints are normally kept about 10 mm thick so that modular bricks plus joint give a regular module and the load is spread evenly over the bed. Joints much thinner cannot accommodate brick size variation, and joints much thicker shrink excessively and weaken the wall.

Question 42Masonry, Plastering and Finishing Works

English bond in brick masonry is identified by:

  1. Headers placed only at the quoins
  2. Continuous stretcher courses with occasional headers
  3. Two stretchers between every header in the same course
  4. Alternate courses of headers and stretchers Correct answer.

Explanation

English bond is formed by laying one course entirely of headers and the next entirely of stretchers, giving great transverse strength and no continuous vertical joint. Flemish bond, by contrast, alternates header and stretcher within each course.

Question 43Masonry, Plastering and Finishing Works

Before plastering a new brick wall, the surface is deliberately roughened and wetted. The main purpose of wetting is to:

  1. Make the wall heavier so plaster grips by weight
  2. Speed up the setting of the cement in the plaster
  3. Increase the thickness of plaster that can be applied
  4. Prevent the dry brick from absorbing water from the mortar too quickly Correct answer.

Explanation

Dry bricks suck water out of the plaster mortar, leaving too little water for cement hydration and causing shrinkage cracks and poor adhesion. Pre-wetting the wall controls this suction so the plaster sets and bonds properly.

Question 44Masonry, Plastering and Finishing Works

In plastering terminology, a 'dado' in a building refers to:

  1. The projecting moulding around a door opening
  2. The sloped weathering on top of a parapet
  3. The lower portion of an internal wall finished differently from the upper part Correct answer.
  4. The horizontal band at the junction of wall and ceiling

Explanation

A dado is the lower part of an internal wall, often finished with tiles, cement plaster or paint to protect it from damp and abrasion up to about 1.2 m. The band at the wall-ceiling junction is the cornice, and the door surround is architrave.

Question 45Masonry, Plastering and Finishing Works

Which mortar mix is generally specified for ordinary load-bearing brick masonry in a vocational building maintenance job?

  1. 1:12 cement-lime mortar
  2. 1:1 cement-sand mortar
  3. 1:6 cement-sand mortar Correct answer.
  4. Pure clay slurry

Explanation

A 1:6 cement-sand mortar gives adequate strength and workability for ordinary load-bearing brickwork and is the common site specification. Very rich mixes are wasteful and shrink, while very lean mixes lack bond strength.

Question 46Masonry, Plastering and Finishing Works

The chief function of a 'key' formed by raking the surface of a first plaster coat is to:

  1. Seal the surface against water penetration
  2. Improve the colour of the final finish
  3. Provide a mechanical grip for the next coat Correct answer.
  4. Reduce the total thickness of plaster

Explanation

Raking or scratching the surface of the backing coat creates grooves into which the next coat keys mechanically, preventing delamination. Without a key, the finishing coat can shell off.

Question 47Masonry, Plastering and Finishing Works

Cement plaster on external walls is commonly provided with grooves or a 'V' joint at intervals mainly to:

  1. Increase the bond of paint to the plaster
  2. Allow rainwater to drain off the wall
  3. Control shrinkage cracking by forming a movement joint Correct answer.
  4. Improve the appearance of the elevation only

Explanation

Plaster shrinks as it dries, and long uninterrupted panels crack randomly; a formed groove acts as a controlled movement or expansion joint so cracking occurs at a planned line. Appearance is secondary to this crack-control function.

Question 48Masonry, Plastering and Finishing Works

Which of the following is a finishing operation rather than a structural masonry operation?

  1. Building the plinth course
  2. Laying the header course
  3. Constructing a quoin
  4. Pointing of mortar joints Correct answer.

Explanation

Pointing is the finishing of raked-out joints with a neat mortar, done after the masonry has been built, to weatherproof and dress the joints. Laying headers, plinth courses and quoins are all structural masonry operations.

Question 49Masonry, Plastering and Finishing Works

A mason is building a 230 mm thick wall and finds that a continuous vertical joint would run through several courses. The most appropriate corrective action is to:

  1. Fill the joint with rich 1:3 mortar and continue
  2. Increase the mortar joint thickness to fill the gap
  3. Introduce a header course or bond stone to break the joint Correct answer.
  4. Reduce the wall thickness to 115 mm

Explanation

A continuous vertical joint is a 'straight joint' that splits the wall into unconnected leaves and greatly reduces strength. Breaking it with a header course or bond stones restores interlocking and distributes load across the wall.

Question 50Masonry, Plastering and Finishing Works

A plastered ceiling shows a network of fine cracks soon after drying. The most likely cause is:

  1. Adequate curing for seven days
  2. Use of a 1:6 mix with clean sand
  3. Excessive richness of the mix and rapid drying Correct answer.
  4. Application of a 12 mm finishing coat on a keyed backing

Explanation

Over-rich cement mixes and rapid loss of water cause high shrinkage strains in the thin plaster, producing craze or map cracking. Leaner, well-graded mixes with proper curing reduce this risk.