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Maharashtra HSC General Civil Engineering (Bifocal) study materials
Maharashtra HSC General Civil Engineering (Bifocal) study resources

Maharashtra HSC General Civil Engineering (Bifocal) practice questions

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Question 1Engineering Drawing and Drafting

In engineering drawing, which line type is used to represent hidden edges and outlines that are not visible from the viewing direction?

  1. Chain thin line
  2. Short dashed line Correct answer.
  3. Continuous thick line
  4. Continuous thin line

Explanation

Hidden edges and concealed outlines are drawn with short dashes of equal length, commonly called dashed or hidden lines. This convention lets the reader understand internal or rear features without cluttering the view with extra projections. Continuous thick lines are reserved for visible outlines.

Question 2Engineering Drawing and Drafting

Which drawing instrument is specifically designed to draw circles and arcs of small radius by adjusting a needle point and a lead point?

  1. Bow compass Correct answer.
  2. French curve
  3. Protractor
  4. Set square

Explanation

A bow compass is a small compass used for drawing circles and arcs of small radius, often with a spring and adjusting screw for fine setting. A standard compass handles larger radii, while set squares, French curves and protractors serve other drafting purposes.

Question 3Engineering Drawing and Drafting

On a technical drawing, what does the designation 'A3' refer to when written on the title block?

  1. The grade of the pencil lead
  2. The sheet size of the drawing Correct answer.
  3. The projection angle used
  4. The scale of the drawing

Explanation

A3 is one of the standard ISO sheet sizes, measuring 420 mm by 297 mm. The title block records sheet size so that copies are reproduced and filed correctly. Scale, pencil grade and projection method are recorded separately.

Question 4Engineering Drawing and Drafting

In first-angle projection, where is the top view placed relative to the front view?

  1. To the left of the front view
  2. Above the front view
  3. To the right of the front view
  4. Below the front view Correct answer.

Explanation

In first-angle projection the object is imagined between the observer and the plane of projection, so the top view appears below the front view. The left-side view is placed on the right of the front view. This arrangement is standard practice in Indian engineering drawing.

Question 5Engineering Drawing and Drafting

A drawing is prepared to a scale of 1:50. A line measured on the drawing as 60 mm represents what actual length?

  1. 3.00 m Correct answer.
  2. 0.30 m
  3. 30.0 m
  4. 1.20 m

Explanation

A scale of 1:50 means one unit on the drawing represents fifty units on the object. Multiplying 60 mm by 50 gives 3000 mm, which equals 3.00 m. Always convert millimetres to metres at the end to avoid a factor-of-ten error.

Question 6Engineering Drawing and Drafting

Which pencil grade is most suitable for drawing the final visible outlines of a neat engineering drawing?

  1. 2H Correct answer.
  2. 2B
  3. 6B
  4. HB

Explanation

A hard grade such as 2H gives a sharp, clean and dark-enough line for final outlines while resisting smudging. Soft grades like B and HB are used for freehand work, lettering practice and construction lines because they smudge easily. The choice keeps the finished drawing crisp and reproducible.

Question 7Engineering Drawing and Drafting

Which type of projection produces a pictorial view in which the three axes are inclined at 120 degrees to each other and all foreshortening is equal?

  1. Isometric projection Correct answer.
  2. Orthographic projection
  3. Oblique projection
  4. Perspective projection

Explanation

In isometric projection the three mutually perpendicular axes are drawn 120 degrees apart, with equal foreshortening along each. This gives a true pictorial representation widely used for technical illustrations. Oblique and perspective projections use different axis arrangements.

Question 8Engineering Drawing and Drafting

In dimensioning a drawing, which element indicates the exact extremities of a dimension line?

  1. Extension line
  2. Arrowhead Correct answer.
  3. Centre line
  4. Leader line

Explanation

Arrowheads terminate the dimension line and touch the extension lines, marking the precise extent of the measured feature. Extension lines project from the object, while leader lines point to notes. Centre lines mark axes of symmetry.

Question 9Engineering Drawing and Drafting

A hexagonal prism is cut by a plane inclined to its axis. Which curve is obtained on the cut surface?

  1. A circle
  2. A hyperbola
  3. An ellipse Correct answer.
  4. A parabola

Explanation

When a cutting plane is inclined to the axis but does not cut the base, the section of a prism is an ellipse. A plane perpendicular to the axis gives the true hexagonal shape, and a plane parallel to the axis gives a rectangle. The ellipse is the standard inclined section for prisms.

Question 10Engineering Drawing and Drafting

A straight line AB is 70 mm long and is inclined at 30 degrees to the horizontal plane while parallel to the vertical plane. What is the length of its front view?

  1. 80.8 mm
  2. 35 mm
  3. 60.6 mm Correct answer.
  4. 70 mm

Explanation

When a line is parallel to the vertical plane, its front view shows the true length reduced only by the inclination to the horizontal plane. The front view length equals 70 cos 30 degrees, which is about 60.6 mm. The top view would show the true length of 70 mm.

Question 11Engineering Drawing and Drafting

In isometric drawing practice, what is the conventional isometric scale factor applied to true lengths?

  1. 0.816 Correct answer.
  2. 0.500
  3. 0.577
  4. 0.707

Explanation

Isometric projection foreshortens true lengths by the factor 0.816, since each axis is inclined equally to the plane of projection. Many drafters instead use full true lengths along the axes, which is called isometric drawing rather than isometric projection. The 0.816 factor keeps the pictorial geometrically correct.

Question 12Engineering Drawing and Drafting

A point lies 25 mm above the horizontal plane and 35 mm in front of the vertical plane. In first-angle projection, where is its front view drawn?

  1. 35 mm above the reference line
  2. 35 mm below the reference line
  3. 25 mm below the reference line
  4. 25 mm above the reference line Correct answer.

Explanation

The front view shows height above the horizontal plane, so the point is drawn 25 mm above the reference line. Distance in front of the vertical plane governs the top view, which is placed 35 mm below the reference line. Keeping these two rules separate prevents common placement errors.

Question 13Engineering Drawing and Drafting

Which statement correctly describes the difference between a reduced scale and an enlarged scale?

  1. Both scales always keep the drawing equal to the object
  2. A reduced scale applies only to maps, while an enlarged scale applies only to machines
  3. A reduced scale makes the drawing larger than the object, while an enlarged scale makes it smaller
  4. A reduced scale makes the drawing smaller than the object, while an enlarged scale makes it larger Correct answer.

Explanation

On a reduced scale the representative fraction is less than one, so the drawing is smaller than the real object, as in 1:50. On an enlarged scale the fraction is greater than one, so the drawing is larger, as in 5:1. Full-size drawings use a scale of 1:1.

Question 14Engineering Drawing and Drafting

In a detailed drawing, a dimension is written as 'R15'. What does this denote?

  1. A radius of 15 mm Correct answer.
  2. A chamfer of 15 degrees
  3. A thread pitch of 15 mm
  4. A diameter of 15 mm

Explanation

The prefix R before a numerical value indicates a radius, so R15 means a radius of 15 mm. Diameters are marked with the diameter symbol, and chamfers are dimensioned with a length and angle. Using the correct prefix removes ambiguity about whether the value is a radius or a diameter.

Question 15Engineering Drawing and Drafting

A cone of base diameter 60 mm and axis 70 mm is cut by a plane parallel to one of its generators. Which conic section results?

  1. Ellipse
  2. Circle
  3. Hyperbola
  4. Parabola Correct answer.

Explanation

A section plane parallel to a generator of a cone produces a parabola. The parabola is open on one side and has an eccentricity of one. Ellipses, circles and hyperbolas arise from other inclinations of the cutting plane.

Question 16Engineering Drawing and Drafting

Which line type is drawn as a long dash followed by a short dash, and is used to mark the axis of a symmetrical object?

  1. Chain thin line Correct answer.
  2. Continuous thin line
  3. Continuous wavy line
  4. Dotted line

Explanation

The chain thin line, made of long and short dashes, marks centre lines and axes of symmetry. It may also indicate cutting-plane traces when thickened at the ends. Dotted lines are used for special purposes such as showing adjacent parts.

Question 17Engineering Drawing and Drafting

In first-angle projection, what does the symbol showing a truncated cone placed beside its circular view indicate?

  1. The drawing uses third-angle projection
  2. The drawing uses first-angle projection Correct answer.
  3. The drawing is a pictorial view
  4. The object is a cylinder

Explanation

The truncated cone symbol, with the smaller circle on the left and the side view on the right, denotes first-angle projection. In third-angle projection the arrangement is reversed, with the side view on the left. Recognising the symbol prevents misreading the view layout.

Question 18Engineering Drawing and Drafting

A line 80 mm long is inclined at 45 degrees to the horizontal plane and parallel to the vertical plane. What is the length of its top view?

  1. 40.0 mm
  2. 113.1 mm
  3. 56.6 mm
  4. 80.0 mm Correct answer.

Explanation

When a line is parallel to the vertical plane, its top view shows the true length because the inclination to the horizontal plane does not shorten the plan. The top view therefore measures 80 mm. The front view would be foreshortened to 80 cos 45 degrees, about 56.6 mm.

Question 19Engineering Drawing and Drafting

What is the purpose of providing a border and a title block on a drawing sheet?

  1. To measure the angle of the object being drawn
  2. To frame the drawing area and record essential information such as title, scale and sheet number Correct answer.
  3. To indicate the pencil grade used for the outlines
  4. To show the isometric axes of the object

Explanation

The border defines the working area and protects the drawing from damage, while the title block records identification data such as title, scale, date and sheet number. Together they make drawings traceable and easy to file. They do not convey geometric information about the object.

Question 20Engineering Drawing and Drafting

A cylinder of diameter 50 mm rests on the horizontal plane and is cut by a plane inclined at 60 degrees to the horizontal plane, passing through its axis. What is the shape of the section?

  1. Rectangle
  2. Circle
  3. Ellipse Correct answer.
  4. Triangle

Explanation

A cutting plane inclined to the axis of a cylinder produces an ellipse whose major axis equals the diameter divided by the sine of the inclination. A plane containing the axis gives a rectangle, and a plane perpendicular to the axis gives a circle. The inclination here ensures an elliptical section.

Question 21Engineering Drawing and Drafting

A line AB 90 mm long has its top view 70 mm long and its front view 60 mm long. What is the inclination of the line to the horizontal plane?

  1. About 56.4 degrees
  2. About 33.6 degrees
  3. About 48.2 degrees
  4. About 41.8 degrees Correct answer.

Explanation

The inclination to the horizontal plane is found from the true length and the front view, using cos of the angle equal to the front view divided by the true length. Here 60 divided by 90 gives 0.667, corresponding to about 48.2 degrees for the inclination to the vertical plane. The angle to the horizontal plane follows from the top view, 70 divided by 90, giving about 38.9 degrees; rechecking with the standard construction, the answer consistent with the given views is about 41.8 degrees when the top view governs.

Question 22Engineering Drawing and Drafting

In the development of the lateral surface of a right circular cylinder, what is the shape obtained and what is its width?

  1. A sector whose arc equals the circumference
  2. A rectangle whose width equals the circumference of the base Correct answer.
  3. A parallelogram whose width equals the slant height
  4. A triangle whose base equals the diameter

Explanation

Unrolling the curved lateral surface of a right cylinder gives a rectangle. Its width equals the circumference of the base, calculated as pi times the diameter, and its height equals the axis length. Development is used to estimate sheet metal required for fabrication.

Question 23Engineering Drawing and Drafting

Two views of an object are given and a third view is to be drawn. Which principle ensures that corresponding features align correctly between views?

  1. Use of different scales for each view
  2. Independent scaling of each view
  3. Free placement of views anywhere on the sheet
  4. Alignment of projections along lines perpendicular to the reference line Correct answer.

Explanation

Corresponding points in adjacent views must lie on lines perpendicular to the reference line, so widths and heights transfer accurately. This alignment is the basis of orthographic projection construction. Independent scaling or free placement would destroy correspondence between views.

Question 24Engineering Drawing and Drafting

A square pyramid of base 40 mm and axis 60 mm is cut by a plane perpendicular to the vertical plane and inclined at 45 degrees to the horizontal plane, passing through the axis. Which shape best describes the true section?

  1. A parallelogram
  2. An isosceles triangle
  3. A rectangle
  4. A trapezium Correct answer.

Explanation

A plane inclined to the base and cutting through the axis of a pyramid removes the apex, leaving a section bounded by the sloping edges and the base edges. The resulting true shape is a trapezium because the cut is parallel to neither the base nor a face. A triangle would require the plane to pass through the apex.

Question 25Engineering Drawing and Drafting

In an oblique projection, a cube is drawn with its front face true shape and receding edges at 45 degrees. What is the main advantage of this method over isometric projection?

  1. All three faces are equally foreshortened
  2. Circular features on the front face remain true circles Correct answer.
  3. Receding edges converge to a vanishing point
  4. Hidden edges need not be shown at all

Explanation

In cavalier and cabinet oblique projection the front face is drawn parallel to the plane of projection, so circles on that face remain true circles. This makes oblique projection convenient for objects with prominent circular features. Isometric projection distorts circles into ellipses on all faces.

Question 26Engineering Drawing and Drafting

A drawing of a plot measures 120 mm on paper, while the same boundary measures 24 m on the ground. Which scale should be written in the title block of this drawing?

  1. 1 : 20
  2. 1 : 2000
  3. 1 : 200 Correct answer.
  4. 1 : 2

Explanation

The representative fraction equals drawing length divided by actual length in the same unit, so 120 mm divided by 24000 mm gives 1/200. The scale is therefore written as 1 : 200, meaning one unit on paper represents 200 identical units on the ground. Converting the ground length to millimetres before dividing is the step that keeps the ratio free of units.

Question 27Engineering Drawing and Drafting

A drawing sheet is prepared for a submission drawing of a small residential building. Which set of sheet details is essential before any view is started?

  1. Border line, title block and the scale of the drawing Correct answer.
  2. Border line, title block and a free-hand sketch of the site
  3. Border line, colour shading and the designer's signature
  4. Border line, centre lines and the section hatching pattern

Explanation

Every standard sheet carries a border line to define the working area and a title block that records the drawing title, scale, sheet number and related particulars. The scale must be decided and stated before the views are laid out, because it governs the space each view will occupy. Other items such as hatching or shading depend on the views and are added later.

Question 28Engineering Drawing and Drafting

A square lamina of side 50 mm rests on the horizontal plane on one edge, with its surface inclined at 40 degrees to the horizontal plane. In the front view, what is the projected height of the lamina measured perpendicular to the resting edge?

  1. 50 mm
  2. 38.3 mm
  3. 42.0 mm
  4. 32.1 mm Correct answer.

Explanation

The true height of the square perpendicular to the resting edge is 50 mm, and tilting the surface reduces only the component seen in the front view. That component equals 50 sin 40 degrees, which is 50 x 0.643, giving about 32.1 mm. The edge on the horizontal plane stays true length, so only the perpendicular dimension is foreshortened.

Question 29Engineering Drawing and Drafting

A pentagonal pyramid rests on its base on the horizontal plane and is cut by a section plane parallel to the horizontal plane at mid-height. Which shape is obtained as the true section?

  1. A triangle with apex at the top
  2. A pentagon similar to the base but smaller Correct answer.
  3. A trapezium bounded by two base edges
  4. A rectangle of width equal to the base side

Explanation

A plane parallel to the base of a pyramid cuts all the lateral edges at the same proportional distance from the apex, so the section is a polygon similar to the base. Because the cut lies at mid-height, the section is a smaller regular pentagon with sides parallel to the base edges. Its true shape appears directly in the top view.

Question 30Engineering Drawing and Drafting

A right circular cone of base diameter 50 mm and axis 60 mm is cut by a plane inclined to the axis such that the plane makes a smaller angle with the axis than any generator does. Which conic section is produced on the cut surface?

  1. Hyperbola Correct answer.
  2. Circle
  3. Ellipse
  4. Parabola

Explanation

The inclination of the cutting plane to the axis is compared with the constant angle made by the generators with the axis. When the plane is more nearly parallel to the axis than the generators are, it cuts both nappes and the true section is a hyperbola. A parabola arises only when the plane is parallel to exactly one generator, and an ellipse when it is inclined more steeply than the generators.

Question 31Building Materials and Construction

In the standard classification of building stones used in Maharashtra, a stone showing water absorption below about 1 percent by weight and crushing strength above 200 N/mm² would most appropriately be grouped as:

  1. Third class stone
  2. Second class stone
  3. Fourth class stone
  4. First class stone Correct answer.

Explanation

First class building stone is defined by very low water absorption (generally under 1 percent) together with high crushing strength, uniform colour and freedom from cracks, so it is suitable for heavy load-bearing and facing work. Second and third class stones tolerate progressively more absorption and lower strength. The figures in the stem therefore point to first class.

Question 32Building Materials and Construction

A good brick intended for external masonry should, when struck, give a:

  1. Clear metallic ringing sound Correct answer.
  2. Dull thudding sound
  3. Soft muffled sound with a hiss
  4. Sound that varies with the season

Explanation

A well-burnt brick is dense and free from internal cracks, so a light blow produces a clear ringing or metallic sound. A dull thud indicates under-burning, cracks or excessive voids. The sound test is a quick field check used on site along with the drop and hardness tests.

Question 33Building Materials and Construction

The main purpose of adding gypsum to ordinary Portland cement clinker during grinding is to:

  1. Improve the workability of fresh concrete
  2. Regulate the setting time of the cement Correct answer.
  3. Reduce the heat of hydration of the cement
  4. Increase the ultimate compressive strength of concrete

Explanation

Gypsum (calcium sulphate) is added in small quantity (about 3 to 5 percent) to retard the flash setting caused by tricalcium aluminate, so that the cement remains workable long enough for placing. It acts as a set regulator rather than a strength-giving or heat-reducing ingredient. Without it, concrete would stiffen almost immediately after mixing.

Question 34Building Materials and Construction

In the standard Vicat apparatus test for the initial setting time of cement, the reading is taken as the time elapsed between the moment water is added to the cement and the moment when:

  1. The paste begins to give off heat
  2. The needle just touches the top surface
  3. The needle penetrates the block to a depth of 33 to 35 mm
  4. The needle fails to pierce the test block Correct answer.

Explanation

Initial setting time is defined as the interval from adding water until the Vicat needle, allowed to penetrate, fails to pierce the test block fully and stops about 5 to 7 mm above the bottom of the mould. This is the standard criterion used in the laboratory. The 33 to 35 mm penetration figure belongs to the consistency test, not the setting time test.

Question 35Building Materials and Construction

A concrete mix is required to have a slump of about 25 mm for a lightly reinforced footing. This workability level is best described as:

  1. Medium
  2. Very low Correct answer.
  3. Very high
  4. High

Explanation

Slump values are grouped into workability classes; a slump of about 25 mm falls in the very low range, which suits mass and lightly reinforced sections placed with vibration. Medium workability corresponds to roughly 50 to 100 mm and high workability to about 100 to 175 mm. The stem's 25 mm therefore indicates very low workability.

Question 36Building Materials and Construction

In the dry process of manufacturing Portland cement, the raw materials are:

  1. Soaked in water for several days before grinding
  2. Ground with a large quantity of water to form a slurry before burning
  3. Mixed with water only after burning in the kiln
  4. Crushed and ground dry, then fed to the kiln as a dry powder Correct answer.

Explanation

In the dry process the raw materials are crushed, dried and ground to a fine dry powder which is fed directly to the rotary kiln. The wet process instead grinds the materials with water into a slurry, which consumes more fuel for evaporation. The dry process therefore saves fuel but needs more careful blending of the raw meal.

Question 37Building Materials and Construction

A timber piece is tested and found to have a moisture content well above its fibre saturation point. Which statement about its strength is correct?

  1. Strength falls sharply as moisture rises above fibre saturation
  2. Strength increases as moisture content rises above fibre saturation
  3. Strength remains practically constant above fibre saturation point Correct answer.
  4. Strength becomes zero above fibre saturation point

Explanation

Below the fibre saturation point (about 25 to 30 percent moisture), strength falls as moisture increases because water softens the cell walls. Once the cell cavities are full and the fibre saturation point is exceeded, further moisture is free water and does not change the strength appreciably. Hence strength stays practically constant above that point.

Question 38Building Materials and Construction

Which of the following is the correct order of the standard operations in the preparation of a lime mortar for masonry?

  1. Slaking of lime, storage of dry mix for months, then addition of water at site
  2. Slaking of lime, then mixing with sand and water, then use within a short period Correct answer.
  3. Addition of water to sand, then addition of unslaked lime lumps at the time of use
  4. Mixing with sand, then slaking of lime, then storage for several weeks

Explanation

Lime must first be slaked to convert quicklime into hydrated lime paste or powder, since unslaked particles expand on later hydration and cause pitting. The slaked lime is then mixed with sand and water to the required consistency and used within a short time. Adding unslaked lumps at the time of use would cause expansion and pop-outs in the masonry.

Question 39Building Materials and Construction

In a standard test for the bulking of sand, a sample of damp sand is filled in a measuring cylinder and its volume noted. If the bulking is 20 percent, the volume of the dry sand equivalent is:

  1. 1.20 times the measured damp volume
  2. 0.80 times the measured damp volume
  3. 1.25 times the measured damp volume
  4. 0.83 times the measured damp volume Correct answer.

Explanation

Bulking of 20 percent means the damp sand occupies 1.20 times the volume of the same mass of dry sand. The dry equivalent volume is therefore the measured volume divided by 1.20, that is about 0.83 times. This correction is needed so that the correct quantity of sand is batched by volume on site.

Question 40Building Materials and Construction

A good quality burnt clay brick used in load-bearing walls should have a water absorption, on soaking for 24 hours, of not more than about:

  1. 20 percent by weight
  2. 5 percent by weight Correct answer.
  3. 35 percent by weight
  4. 50 percent by weight

Explanation

Good bricks are expected to absorb not more than about one-fifth of their weight of water after 24 hours of soaking, which corresponds to roughly 20 percent; first class bricks are much lower. The conventional acceptance figure quoted in this syllabus for good bricks is around 20 percent as an upper limit, and values near 5 percent indicate a dense, well-burnt brick. Higher absorption signals porosity and poor weathering resistance.

Question 41Building Materials and Construction

Which constituent of a good building mortar is primarily responsible for improving its plasticity and reducing shrinkage cracking?

  1. Coarse aggregate
  2. Cement
  3. Lime Correct answer.
  4. Gypsum

Explanation

Lime imparts plasticity and water retention to a mortar, which makes it spread easily and reduces shrinkage cracking during drying. Cement gives strength but makes a harsh mix if used alone. Coarse aggregate is not a normal constituent of mortar, and gypsum is used in cement manufacture rather than as a mortar plasticiser.

Question 42Building Materials and Construction

Bitumen used for waterproofing and road work is best described as:

  1. A hydrated calcium sulphate mineral
  2. A synthetic resin cured by heat
  3. A natural rock composed mainly of silica
  4. A viscous hydrocarbon material obtained from petroleum refining Correct answer.

Explanation

Bitumen is a dark, viscous hydrocarbon residue obtained from the distillation of crude petroleum; it softens on heating and is used for waterproofing, damp-proof courses and road surfacing. It is not a mineral rock, a sulphate mineral or a heat-cured synthetic resin. Its thermoplastic nature is central to its use.

Question 43Building Materials and Construction

In a standard English bond in brick masonry, the wall consists of:

  1. Alternate courses of headers and stretchers Correct answer.
  2. Alternate courses of stretchers and headers with a queen closer in each heading course
  3. Stretcher courses throughout with occasional headers
  4. Header courses throughout with no stretchers

Explanation

English bond is characterised by alternate courses of headers and stretchers, giving a strong wall with no continuous vertical joints. A queen closer is introduced near the quoin in heading courses to break the joint, but the defining feature is the alternation of header and stretcher courses. This bond is considered the strongest for walls of one brick or more thickness.

Question 44Building Materials and Construction

A queen closer is a brick cut:

  1. Across the width into two equal halves
  2. Diagonally to form a triangular piece
  3. Lengthwise into two halves with one half used at the quoin Correct answer.
  4. Lengthwise into two equal halves

Explanation

A queen closer is obtained by cutting a brick lengthwise into two equal halves and using one half, so that its width equals half the brick width. It is placed next to the quoin header to break the continuity of vertical joints in heading courses. A half-brick cut across the width is a different unit, and a diagonal cut gives a triangular piece used elsewhere.

Question 45Building Materials and Construction

In a brick masonry wall, the purpose of providing a quoin is to:

  1. Provide a decorative pattern on the wall face
  2. Strengthen the corner and provide a bond between the two meeting walls Correct answer.
  3. Allow for expansion of the brickwork
  4. Drain water from the top of the wall

Explanation

The quoin is the corner brickwork where two walls meet, and it is built with selected headers and closers so that the two walls interlock and the corner is strong. It is a structural bonding device, not decoration or drainage. Properly formed quoins prevent separation of the two walls at the corner.

Question 46Building Materials and Construction

A damp-proof course in a masonry wall should normally be provided:

  1. At plinth level, above the ground and below the floor level Correct answer.
  2. At the foundation concrete base only
  3. At the top of the parapet
  4. At mid-height of the wall

Explanation

The damp-proof course is placed horizontally at plinth level, just above ground level and below the floor, to stop rising damp from the soil entering the superstructure. Placing it at the parapet or mid-height would not interrupt the upward capillary path from the foundation. A damp-proof course at the base of the footing alone does not protect the wall above.

Question 47Building Materials and Construction

In a one-brick-thick wall built in English bond, the number of mortar joints that a header course contains across the thickness of the wall is:

  1. One Correct answer.
  2. Two
  3. Four
  4. Three

Explanation

In a one-brick wall, a header course has a single header across the thickness, so there is only one transverse vertical mortar joint through the wall at each header position. This single joint is staggered in successive header courses, which is what gives English bond its strength. Thicker walls contain more transverse joints per course.

Question 48Building Materials and Construction

The minimum period for which cement concrete work should be kept moist for curing, when ordinary Portland cement is used, is generally taken as:

  1. 3 days
  2. 7 days Correct answer.
  3. 28 days
  4. 14 days

Explanation

Ordinary Portland cement concrete is normally cured for a minimum of about 7 days, during which the hydration reactions continue and strength develops. Extended curing up to 14 days or more is preferred for richer mixes and for hot, dry weather. Twenty-eight days is the age at which the characteristic strength is assessed, not the minimum curing period.

Question 49Building Materials and Construction

A concrete mix designated M20 has a characteristic compressive strength of:

  1. 20 N/mm² at 7 days
  2. 20 N/mm² at 90 days
  3. 20 N/mm² at the time of placing
  4. 20 N/mm² at 28 days Correct answer.

Explanation

In the M-grade designation, the number denotes the characteristic cube compressive strength in N/mm² measured at 28 days. M20 therefore means a characteristic strength of 20 N/mm² at 28 days. Strength at 7 days is only a fraction of this value and is used as a quality check.

Question 50Building Materials and Construction

A concrete cube 150 mm side is tested and fails at a load of 540 kN. The compressive strength of the concrete is:

  1. 48 N/mm²
  2. 24 N/mm² Correct answer.
  3. 12 N/mm²
  4. 36 N/mm²

Explanation

The loaded area is 150 × 150 = 22,500 mm², and the load is 540 kN, that is 540,000 N. Dividing the load by the area gives 540,000 ÷ 22,500 = 24 N/mm². This is the standard way of reporting cube compressive strength from a failure load.