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Multiple choice question for engineering

Set 1

1. The front and top view are sometimes not sufficient to convey all the information regarding the object. Additional views are therefore projected on other planes known as____________
a) auxiliary vertical plane
b) auxiliary inclined plane
c) auxiliary plane
d) horizontal and Vertical plane

View Answer

Answer: c [Reason:] Any view obtained by a projection on a plane other than the horizontal, frontal, and profile projection planes is an auxiliary view. A primary auxiliary view is projected onto a plane that is perpendicular to one of the principal planes of projection and is inclined to the other two. A secondary auxiliary view is projected from a primary auxiliary view onto a plane that is inclined to all three principal projection planes as shown in the figure below.

civil-engineering-drawing-questions-answers-projection-straight-lines-q1

2. Auxiliary views cannot be used for the determining _____________
a) the true length of a line
b) the point-view of a line
c) the edge-view of a line
d) the apparent size

View Answer

Answer: d [Reason:] The auxiliary views may also be used for determining – true length of a line, point-view of a line, edge- view of a line, true size and form of a plane etc as shown in the figure below.

civil-engineering-drawing-questions-answers-projection-straight-lines-q2

3. Auxiliary planes are of _______types.
a) two
b) one
c) three
d) six

View Answer

Answer: a [Reason:] These are A.V.P ( Auxiliary vertical plane) and A.I.P. (Auxiliary inclined plane ). Auxiliary vertical plane is perpendicular to the H.P. and inclined to the V.P. projection on an A.V.P. is called auxiliary front plane. Auxiliary inclined plane is perpendicular to the V.P. and inclined to the H.P. projection on an A.I.P. is called auxiliary top view.

4. What are non-parallel and non-intersecting lines called?
a) Spiral lines
b) Parallel lines
c) Skew lines
d) Perpendicular lines

View Answer

Answer: c [Reason:] A simple example of a pair of skew lines is the pair of lines through opposite edges of a regular tetrahedron. Two lines that both lie in the same plane must either cross each other or be parallel, so skew lines can exist only in three or more dimensions. Two lines are skew if and only if they are not coplanar. Referring the figure below, here the line through segment AD and the line through segment B1B are skew lines because they are not in the same plane.

civil-engineering-drawing-questions-answers-auxiliary-projection-q4

5. The shortest distance between two parallel lines is equal to the length of the perpendicular drawn between them. If its true length is to be measured, then the two given parallel lines should be shown in their_________ views.
a) top
b) front
c) point
d) line

View Answer

Answer: c [Reason:] If the point views of the lines are required, then first they have to be shown in their true lengths in one of the orthographic views. If none of the orthographic views show the given lines in their true lengths, an auxiliary plane parallel to the two given lines should be set up to project them in their true lengths on it. Even the auxiliary view which shows the lines in their true lengths may not show the perpendicular distance between them in true length. Hence another auxiliary plane perpendicular to the two given lines should be set up. Then the lines appear as points on this auxiliary plane and the distance between these point views will be the shortest distance between them.

6. The end projectors of a line AB is 40 mm. The point A is 24 mm above HP and 10 mm in front of VP. Point B is 46 mm above HP and 46 mm in front of VP. What will be the True length of the line?
a) 57 mm
b) 37 mm
c) 50 mm
d) 47 mm

View Answer

Answer: a [Reason:] Refer the figure below and the following steps- • Draw the XY line. Draw two line perpendicular to XY line separated by a horizontal distance of 40 mm. • Along the first line mark points a’ and a 24 mm above and 10 mm below XY line. • Along the second line mark b and b’ 46 mm above and below XY line. • Draw a reference line X1 Y1 parallel to line ab to represent the AVP. • Through a and b, draw projectors to X1 Y1 line and extend it. • Mark a2’ such that 3-a2’ = 5-a’. similarly mark b2’ such that 4-b2’ = 6b’. • Join a2’-b2’ to obtain the true length of the line. • The inclination of the line a2’-b2’ with X1Y1 line is the true inclination of the line with HP. • Draw X2Y2 parallel to the front view a’b’ and project the auxiliary top view a1b1 in the similar manner. The inclination of the line a1-b1 with X2Y2 line is the true inclination of the line with VP. By measurement, the following dimensions are obtained: True length of the line is 57 mm. civil-engineering-drawing-questions-answers-auxiliary-projection-q6

7. Plane appears as foreshortened surface in all the projection planes is known as _________
a) The parallel plane
b) The vertical plane
c) The slant plane
d) The horizontal plane

View Answer

Answer: c [Reason:] A slant plane is defined as a plane that appears as a line in at least one of the standard views of projection (top, front), and foreshortened in the other views.

civil-engineering-drawing-questions-answers-auxiliary-projection-q7

8. To save space on the drawing or to save time only ___________ view may be drawn.
a) Half auxiliary
b) Full auxiliary
c) Front
d) Top

View Answer

Answer: a [Reason:] If an auxiliary view is symmetrical, and if it is necessary to save space on the drawing or to save time, only half of the auxiliary view may be drawn, as shown below. In this case, half of a regular view is also shown since the bottom flange is also symmetrical as shown in the figure below.

civil-engineering-drawing-questions-answers-auxiliary-projection-q8

9. Planes which are inclined to both the reference planes are called __________
a) vertical planes
b) inclined planes
c) horizontal planes
d) oblique planes

View Answer

Answer: d [Reason:] Oblique projection is a simple type of technical drawing of graphical projection used for producing two-dimensional images of three-dimensional objects. The objects are not in perspective, so they do not correspond to any view of an object that can be obtained in practice, but the technique does yield somewhat convincing and useful images. The plane at which these activity occur refers to as Oblique planes.

10. Auxiliary views tend to make use of ___________ projection.
a) orthographic projection
b) axonometric projection
c) oblique projection
d) isometric projection

View Answer

Answer: b [Reason:] Axonometric projection is a type of orthographic projection used for creating a pictorial drawing of an object, where the lines of sight are perpendicular to the plane of projection, and the object is rotated around one or more of its axes to reveal multiple sides.

11. In ____________, the direction of viewing is such that two of the three axes of space appear equally foreshortened.
a) orthographic projection
b) trimetric projection
c) dimetric projection
d) isometric projection

View Answer

Answer: b [Reason:] In dimetric projection, the direction of viewing is such that two of the three axes of space appear equally foreshortened, of which the attendant scale and angles of presentation are determined according to the angle of viewing; the scale of the third direction (vertical) is determined separately. Approximations are common in dimetric drawings.

12. In _________ the parallel projection rays are not perpendicular to the viewing plane as with orthographic projection, but strike the projection plane at an angle other than ninety degrees.
a) isometric projections
b) orthographic projections
c) axonometric projection
d) oblique projections

View Answer

Answer: d [Reason:] In both orthographic and oblique projection, parallel lines in space appear parallel on the projected image. Because of its simplicity, oblique projection is used exclusively for pictorial purposes rather than for formal, working drawings. In an oblique pictorial drawing, the displayed angles among the axes as well as the foreshortening factors (scale) are arbitrary. The distortion created thereby is usually attenuated by aligning one plane of the imaged object to be parallel with the plane of projection thereby creating a true shape, full-size image of the chosen plane.

Set 2

1. Planes are formed when any three _________ points are joined.
a) non-collinear
b) collinear
c) concentric
d) eccentric

View Answer

Answer: a [Reason:] A plane is as two dimensional surface having length and breadth with negligible thickness. They are formed when any three non-collinear points are joined. Planes are bounded by straight/curved lines and may be either regular or an irregular. Regular plane surface are in which all the sides are equal. Irregular plane surface are in which the lengths of the sides are unequal.

2. When the plane surface is held with its surface parallel to one of the planes of projection, the view of the plane surface projected on it will be in __________
a) apparent shape
b) point shape
c) true shape
d) line shape

View Answer

Answer: c [Reason:] When the plane surface is held with its surface parallel to one of the planes of projection, the view of the plane surface projected on it will be in true shape because all the sides or the edges of the plane surface will be parallel to the plane of projection on which the plane surface is projected.

3. When a plane surface is inclined to any plane of projection, the view of the plane surface projected on it will be its ____________
a) point shape
b) true shape
c) straight line
d) apparent shape

View Answer

Answer: d [Reason:] An inclined surface is a surface that is perpendicular to one of the principal planes, and is at some angle to the remaining two principal planes. As such, an inclined surface will always appear as a line in one of the principal views and as a foreshortened area in the other two views. An inclined surface will not appear true size in a principal view.

4. A plane surface may be positioned in space with reference to the three principal planes of projection in any of the following positions, which one is false?
a) Parallel to one of the principal planes and perpendicular to the other two
b) Perpendicular to one of the principal planes and inclined to the other two
c) Parallel to both the planes
d) Inclined to all the three principal planes

View Answer

Answer: c [Reason:] Planes may be divided into two main types: Perpendicular planes and Oblique planes. And this perpendicular plane is further divided into three parts- a) Parallel to one of the principal planes and perpendicular to the other two. b) Perpendicular to one of the principal planes and inclined to the other two. c) Inclined to all the three principal planes.

5. An equilateral triangular lamina of 25 mm sides lies with one of its edges on HP such that the surface of the lamina is inclined to HP at 60 deg. The edge on which it rests is inclined to VP at 60 deg. How many lines with 3 coordinates will appear during the projection?
a) 5
b) 6
c) 3
d) 2

View Answer

Answer: d [Reason:] Lines above xy line i.e. a’b’(c’) representing lines are the required lines, refer the figure below.

civil-engineering-drawing-questions-answers-plane-projection-q5

6. A circular lamina inclined to the VP appears in the front view as an ellipse of major axis 30mm & minor axis 15 mm. The major axis is parallel to both HP and VP. One end of the minor axis is in both the HP and VP. Determine the inclination of the lamina with the VP.
a) 45o
b) 90o
c) 60o
d) 105o

View Answer

Answer: c [Reason:] On measuring the value of φ by making the projection, its value is found.

civil-engineering-drawing-questions-answers-plane-projection-q6

7. A hexagonal lamina of 30 mm sides rests on HP with one of its corners touching VP and the surface inclined at 45 deg. to it. One of its edges inclined to HP at 30 deg. What will be the value of α?
a) 32.31°
b) 42.32°
c) 52.32°
d) 62.32°

View Answer

Answer: a [Reason:] Referring the figure below, on measuring the value of α, inclination is known.

civil-engineering-drawing-questions-answers-plane-projection-q7

8. A rectangular lamina of sides 20 mm X 25mm has an edge in HP and adjoining edge in VP, is tilted such that the front view appears as a rectangle of 20 mm X 15 mm. The edge which is in VP is 30 mm from the right profile plane. Find its inclinations with the corresponding principal planes.
a) 43.43o
b) 53.13o
c) 43.13o
d) 67.34o

View Answer

Answer: b [Reason:] Referring the figure below, on measuring the value of φ, inclination is known.

civil-engineering-drawing-questions-answers-plane-projection-q8

9. A mirror 30 mm X 40 mm is inclined to the wall such that its front view is a square of 30mm side. The longer side of the mirror appear perpendicular to both HP and VP. Find the inclination of the mirror with the wall.
a) 48.76o
b) 36.78o
c) 51.76o
d) 41.41o

View Answer

Answer: d [Reason:] Referring the figure below, on measuring the value of φ, inclination is known.

10. When a plane is perpendicular to a reference plane, its projection on that plane is a_____
a) straight line
b) true line
c) apparent line
d) point

View Answer

Answer: a [Reason:] Top views of the two end points of a line, when joined, give the top view of the line. Front views of the two end points of the line, when joined, give the front view of the line. Both these Projections are straight lines.

Set 3

1. A ________ is solid bounded only by plane surfaces (faces).
a) square
b) rectangle
c) regular polyhedron
d) triangle

View Answer

Answer: c [Reason:] In geometry, a polyhedron (plural polyhedra or polyhedrons) is a solid in 3 dimensions with flat polygonal faces, straight edges and sharp corners or vertices. The word polyhedron comes from the Classical Greek. A convex polyhedron is the convex hull of finitely many points, not all on the same plane. Cubes and pyramids are examples of convex polyhedra. A polyhedron is a 3-dimensional example of the more general polytope in any number of dimensions.

civil-engineering-drawing-questions-answers-solid-projection-q1

The following figure has six questions, answer the questions which are as follows:-

2. Which types of prism does the 3rd figure represents?
a) Triangular
b) Square
c) Pentagon
d) Oblique

View Answer

Answer: c [Reason:] A solid (3-dimensional) object which has six faces that are rectangles. It has the same cross-section along a length, which makes it a prism. It is also a “cuboid”.

civil-engineering-drawing-questions-answers-solid-projection-q2

3. Which types of prism does the 6rd figure represents?
a) Triangular
b) Square
c) Pentagon
d) Oblique

View Answer

Answer: d [Reason:] A prism with bases that are not aligned one directly above the other. Note: The lateral faces of an oblique prism are parallelograms. Refer the figure b below.

civil-engineering-drawing-questions-answers-solid-projection-q3

4. Which types of prism does the 2rd figure represents?
a) Triangular
b) Square
c) Pentagon
d) Oblique

View Answer

Answer: b [Reason:] A square prism is a three-dimensional shape with two square bases and flat sides. Therefore, all square prisms consist of at least two squares, even if not all the sides are squares, as long as the bases are square, there is a square prism. Cubes are a common example of squareprisms.

civil-engineering-drawing-questions-answers-solid-projection-q4

5. Which types of prism does the 5th figure represents?
a) Triangular
b) Square
c) Pentagon
d) Rectangular

View Answer

Answer: d [Reason:] In geometry, a cuboid is a convex polyhedron bounded by six quadrilateral faces, whose polyhedral graph is the same as that of a cube. While mathematical literature refers to any such polyhedron as a cuboid, other sources use “cuboid” to refer to a shape of this type in which each of the faces is a rectangle (and so each pair of adjacent faces meets in a right angle); this more restrictive type of cuboid is also known as a rectangular cuboid, right cuboid, rectangular box, rectangular hexahedron, right rectangular prism, or rectangular parallelepiped.

civil-engineering-drawing-questions-answers-solid-projection-q5

6. Which types of prism does the 1rd figure represents?
a) Triangular
b) Square
c) Pentagon
d) Equilateral triangular

View Answer

Answer: a [Reason:] In geometry, a triangular prism is a three-sided prism; it is a polyhedron made of a triangular base, a translated copy, and 3 faces joining corresponding sides. A right triangular prism has rectangular sides, otherwise it is oblique.

civil-engineering-drawing-questions-answers-solid-projection-q6

7. Which types of prism does the 4th figure represents?
a) Triangular
b) Hexagonal
c) Pentagon
d) Oblique

View Answer

Answer: b [Reason:] The hexagonal prism is a prism with hexagonal base. This polyhedron has 8 faces, 18 edges, and 12 vertices. Since it has eight faces, it is an octahedron. However, the term octahedron is primarily used to refer to the regular octahedron, which has eight triangular faces.

civil-engineering-drawing-questions-answers-solid-projection-q7

8. What does the dotted line in the centre of the figure represents?
a) Axis
b) Vertical line
c) Separation line
d) Centre line

View Answer

Answer: a [Reason:] It is the imaginary line connecting the end faces is called axis, also a line, used as a reference to determine position, symmetry and rotation is called axis and is shown in figure below. It can be of four types- a) In coordinate geometry and trigonometry as y, x and z axis, b) Axis of symmetry, c) Axis of a solid and d) Axis of rotation.

civil-engineering-drawing-questions-answers-solid-projection-q8

9. When the prism is placed vertically on one of its end faces, the end face on which the prism rests is called the________ and the vertical side faces are the________ faces.
a) bottom, lateral
b) base, lateral
c) base, longitudinal
d) horizontal, lateral

View Answer

Answer: b [Reason:] When the prism is placed vertically on one of its end faces, the end face on which the prism rests is called the base and the vertical side faces are the lateral faces.

civil-engineering-drawing-questions-answers-solid-projection-q9

10. When the axis of the pyramid is perpendicular to its base, which pyramid does it represent?
a) Perpendicular pyramid
b) Square pyramid
c) Oblique pyramid
d) Right pyramid

View Answer

Answer: d [Reason:] A right pyramid is a pyramid with a base that is a regular polygon and whose apex is directly above the centre of the base. The surface area of a right pyramid can be calculated, using. the following formula: SA 5 B 1. Ps , where B is the area of the base, P is the perimeter of the base, and s is the slant height.

civil-engineering-drawing-questions-answers-solid-projection-q10

11. On projection of a cylinder on a plane, the shape appeared by front view will be _____________
a) line
b) square
c) point
d) rectangle

View Answer

Answer: d [Reason:] When the solid is placed with the base on HP position, in the top view, the base will be projected in its true shape. Hence, when the base of the solid is on HP, the top view is drawn first and then the front view and the side views are projected from it. Figure 10 shows a cylinder with its axis perpendicular to HP. There is only one position in which a cylinder or a cone may be placed with its base on HP.

civil-engineering-drawing-questions-answers-solid-projection-q11

Set 4

1. __________is a building material used for the protective and/or decorative coating of walls and ceilings and for moulding and casting decorative elements.
a) Cement
b) Aggregate
c) Plaster
d) Paint

View Answer

Answer: c [Reason:] The most common types of plaster mainly contain either gypsum, lime, or cement, but all work in a similar way. The plaster is manufactured as a dry powder and is mixed with water to form a stiff but workable paste immediately before it is applied to the surface. The reaction with water liberates heat through crystallization and the hydrated plaster then hardens.

2. __________plaster is a mixture of clay, sand and water with the addition of plant fibers for tensile strength over wood lath.
a) Loam
b) Sand
c) Gypsum
d) Clay

View Answer

Answer: d [Reason:] Clay plaster has been used since antiquity. Settlers in the American colonies used clay plaster on the interiors of their houses: “Interior plastering in the form of clay antedated even the building of houses of frame, and must have been visible in the inside of wattle filling in those earliest frame houses in which …wainscot had not been indulged.

3. Gypsum plaster, or plaster of Paris, is produced by heating __________to about 300 °F.
a) gypsum
b) clinker
c) calcium
d) lime

View Answer

Answer: a [Reason:] CaSO4•2H2O + heat → CaSO4•0.5H2O + 1.5H2O (released as steam). When the dry plaster powder is mixed with water, it re-forms into gypsum. The setting of unmodified plaster starts about 10 minutes after mixing and is complete in about 45 minutes; but not fully set for 72 hour. If plaster or gypsum is heated above 266 °F (130 °C), hemihydrate is formed, which will also re-form as gypsum if mixed with water.

4. Lime plaster is a mixture of calcium hydroxide and sand (or other inert fillers).
a) True
b) False

View Answer

Answer: a [Reason:] Lime plaster was a common building material for wall surfaces in a process known as lath and plaster, whereby a series of wooden strips on a studwork frame was covered with a semi-dry plaster that hardened into a surface. The plaster used in most lath and plaster construction was mainly lime plaster, with a cure time of about a month.

5. To make lime plaster, limestone (calcium carbonate) is heated above approximately 50 °C to produce quicklime.
a) True
b) False

View Answer

Answer: b [Reason:] To make lime plaster, limestone (calcium carbonate) is heated above approximately 850 °C to produce quicklime. Water is then added to produce slaked lime (calcium hydroxide), which is sold as a wet putty or a white powder. Additional water is added to form a paste prior to use. The paste may be stored in airtight containers.

6. civil-engineering-drawing-questions-answers-quiz-q6 is a rubbed, keyed or grooved type of pointing.
a) True
b) False

View Answer

Answer: a [Reason:] This pointing is also a modification of flush pointing in which groove is formed at its mid height, by a pointing tool. It gives good appearance.

7. Heat resistant plaster is a building material used for coating walls and chimney breasts.
a) True
b) False

View Answer

Answer: a [Reason:] Its purpose is to replace conventional gypsum plasters in cases where the temperature can get too high for gypsum plaster to stay on the wall. Heat resistant plaster should be used in cases where the wall is likely to exceed temperatures of 50 °C.

8. Cracks in plastering may be caused by settlement of the building, by the use of inferior materials or by bad workmanship.
a) True
b) False

View Answer

Answer: a [Reason:] However, due to none of these, cracks may yet ensue by the too fast drying of the work, caused through the laying of plaster on dry walls which suck from the composition the moisture required to enable it to set, by the application of external heat or the heat of the sun, by the laying of a coat upon one which has not properly set, the cracking in this case being caused by unequal contraction, or by the use of too small a proportion of sand.

9. Instead of plastering entire surface of the masonry, special mortar finishing work is done to the exposed joints. This is called pointing.
a) True
b) False

View Answer

Answer: a [Reason:] It consists of raking the joints to a depth of 10 mm to 20 mm and filling it with richer mortar mixes. In case of lime mortar pointing mix used is 1:2 and in case of cement mortar pointing mix used is 1:3. Pointing is ideally suited for stone masonry because stones are having attractive colours and good resistance to penetration by water.

10. One differentiates between interior and exterior fireproofing. Exterior products are typically less substantial, with lower densities and lower cost. Interior products have to withstand more extreme fire and other environmental conditions.
a) True
b) False

View Answer

Answer: b [Reason:] One differentiates between interior and exterior fireproofing. Interior products are typically less substantial, with lower densities and lower cost. Exterior products have to withstand more extreme fire and other environmental conditions.

11. Laths are about an inch wide, and are made in three thicknesses; single (5 to 6 inch thick), lath and a half ( 4 inch thick), and double (3–5 inch thick).
a) True
b) False

View Answer

Answer: b [Reason:] Laths are about an inch wide, and are made in three thicknesses; single (1⁄8 to 3⁄16 inch thick), lath and a half (1⁄4 inch thick), and double (3⁄8–1⁄2 inch thick).

12. Cement plaster is a mixture of suitable plaster, sand, _____________and water.
a) fine aggregate
b) portland cement
c) cement
d) plaster

View Answer

Answer: b [Reason:] It is normally applied to masonry interiors and exteriors to achieve a smooth surface. Interior surfaces sometimes receive a final layer of gypsum plaster. Walls constructed with stock bricks are normally plastered while face brick walls are not plastered. Various cement-based plasters are also used as proprietary spray fireproofing products.

13.Name the type of pointing, where mortar is pressed hard in the raked joints and by finishing off flush with the edge of masonry units. The edges are neatly trimmed with trowel and straight edge.
a) Struck pointing
b) V-pointing
c) Weathered pointing
d) Flush pointing

View Answer

Answer: d [Reason:] It does not give good appearance. But, flush pointing is more durable because of resisting the provision of space for dust, water etc., due to this reason, flush pointing is extensively used. civil-engineering-drawing-questions-answers-analysis-rates-plastering-pointing-q13

14. The below figure shows ___________
civil-engineering-drawing-questions-answers-analysis-rates-plastering-pointing-q14

a) struck pointing
b) v-pointing
c) weathered pointing
d) beaded pointing

View Answer

Answer: d [Reason:] It is a special type of pointing which is formed by a steel or ironed with a concave edge. It gives good appearance, but it will damage easily when compared to other types.

15. _________pointing is made by making a projection in the form of V-shape.
a) V-pointing
b) Struck pointing
c) Weathered pointing
d) Surface pointing

View Answer

Answer: a [Reason:] This type of pointing is made similar to keyed or grooved pointing by suitably shaping the end of the steel rod to be used for forming the groove. V pointing pointing is formed by forming v-groove in the flush finishing face. civil-engineering-drawing-questions-answers-analysis-rates-plastering-pointing-q15

Set 5

1. Reinforced cement concrete work is usually estimated under ________items.
a) two
b) three
c) four
d) one

View Answer

Answer: a [Reason:] The concrete work including centering and shuttering, and binding of steel bars in position is taken under one item in cu m (cu ft) and the steel reinforcement and its bending is taken under one item in (cwt).

2. The density of steel may be taken as _______________
a) 68.5 quintal per cu m
b) 9.85 grams per cu m
c) 390 lbs per cu ft
d) 78.5 quintal per cu m

View Answer

Answer: d [Reason:] The density of steel may be taken as 78.5 quintal per cu m or 7.85 grams per cu m, 390 lbs per cu ft. The percentage of steel reinforcement depends on the design of the structure.

3. In R.C.C. work the end or side covers for steel bar may be taken as ____________
a) 4cm to 5cm
b) 7cm to 9cm
c) 6cm to 9cm
d) 3cm to 7cm

View Answer

Answer: a [Reason:] In R.C.C. work the end or side covers for steel bar may be taken as 4cm to 5cm (1 1/2” to 2”) and the bottom and top covers may be taken as 1.2 cm to 2 cm(1/2” to 3/4”) for slab and 2.5 cm to 5cm (1” to 2”) for beams.

4. Concrete reinforced with fibers (which are usually steel, glass, or plastic fibers) is less expensive than hand-tied rebar, while still increasing the tensile strength many times.
a) True
b) False

View Answer

Answer: a [Reason:] A thin and short fiber, for example short, hair-shaped glass fiber, is only effective during the first hours after pouring the concrete (its function is to reduce cracking while the concrete is stiffening), but it will not increase the concrete tensile strength. A normal-size fiber for European shotcrete (1 mm diameter, 45 mm length—steel or plastic) will increase the concrete’s tensile strength.

5. Resistant to weak acids and especially sulfates, this cement cures slowly and has very low durability and strength.
a) True
b) False

View Answer

Answer: b [Reason:] Resistant to weak acids and especially sulfates, this cement cures quickly and has very high durability and strength. It was frequently used after World War II to make precast concrete objects. However, it can lose strength with heat or time (conversion), especially when not properly cured. After the collapse of three roofs made of prestressed concrete beams using high alumina cement, this cement was banned in the UK in 1976. Subsequent inquiries into the matter showed that the beams were improperly manufactured, but the ban remained.

6. The coefficient of thermal expansion of concrete is similar to that of steel, eliminating large internal stresses due to differences in thermal expansion or contraction.
a) True
b) False

View Answer

Answer: a [Reason:] An average value for the coefficient of thermal expansion of concrete is about 10 millionths per degree Celsius (10×10-6/C), although values ranging from 7 to 12 millionths per degree Celsius have been observed.

7. If a material with high strength in tension, such as steel, is placed in concrete, then the composite material, reinforced concrete, resists not only compression but also bending and other direct tensile actions.
a) False
b) True

View Answer

Answer: b [Reason:] A reinforced concrete section where the concrete resists the compression and steel resists the tension can be made into almost any shape and size for the construction industry. FRP composites and Construction Parameters.

8. Another, cheaper way of protecting rebars is coating them with calcium sulphate.
a) True
b) False

View Answer

Answer: b [Reason:] Another, cheaper way of protecting rebars is coating them with zinc phosphate. Zinc phosphate slowly reacts with calcium cations and the hydroxyl anions present in the cement pore water and forms a stable hydroxyapatite layer.

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