Building Construction Technology MCQs for Civil Engineers – Part 3

Correct Answer: 10 cm, 20 cm, 30 cm

Explanation: The dimensions of a slump mold used in the slump test for concrete are typically 10 cm (top diameter), 20 cm (bottom diameter), and 30 cm (height). The slump test measures the consistency and workability of fresh concrete.

Correct Answer: All of the above

Explanation: Proper proportioning of concrete ensures not only the desired strength and workability but also factors in durability and water tightness of the structure. It involves selecting appropriate ratios of cement, aggregates, and water to achieve the desired concrete properties.

Correct Answer: P = (x-z / z-y)x100

Explanation: The correct formula for calculating the percentage (p) of fine aggregates to combined aggregates based on the fineness moduli is P = (x-z / z-y)x100.

Correct Answer: 1:1.5:3

Explanation: The correct ratio of various ingredients (cement: sand: aggregates) in concrete of grade M₂₀ is typically 1:1.5:3. The specific mix proportions may vary based on design requirements and local standards.

Correct Answer: 1:2:4

Explanation: The correct ratio of various ingredients (cement, sand, aggregates) in concrete of grade M₁₅₀ is typically 1:2:4. Higher-grade concrete mixes may have different proportions based on design specifications.

Correct Answer: M₁₀₀

Explanation: The ratio of concrete ingredients 1:3:6 corresponds to a lower-grade concrete, typically referred to as M₁₀₀. Higher-grade concrete mixes have lower water-cement ratios and higher proportions of cement for increased strength.

Correct Answer: Efflorescence effect on the wall

Explanation: Efflorescence is a deposit of salts that can appear on the surface of masonry walls. While it is related to moisture, it is not a direct source of dampness. The main sources of dampness are rain penetration, rising damp from the ground, and condensation.

Correct Answer: An allowance for the entrained air is made

Explanation: When designing air-entrained concrete, an allowance for the entrained air is made. Air entrainment is achieved by adding air-entraining agents to the mix, and it is beneficial for improving freeze-thaw resistance and workability.

Correct Answer: All of the above

Explanation: An ideal warehouse is provided with waterproof masonry walls, a waterproof roof, and few windows that remain generally closed. This design helps prevent moisture ingress, ensuring the protection of goods stored inside.

Correct Answer: All of the above

Explanation: The specifications of a cement bag for storage typically include a weight of 50 kg, a height of 18 cm, and a plan area of 3000 sq. cm. These specifications ensure standardization for handling and storage of cement bags.

Correct Answer: Pressure compaction of the bags on lower layers

Explanation: Warehouse pack of cement refers to the pressure compaction of the bags on the lower layers in a warehouse. It ensures that the stored bags are compacted under the pressure of the bags in the upper layers, optimizing storage space.

Correct Answer: 2700 bags

Explanation: The number of cement bags to be stored can be calculated using the formula: Number of bags = (Effective plan area × Maximum height of piles) / Volume of one bag. Substituting the values, we get (54 m² × 270 cm) / (50 kg/bag), which is approximately 2700 bags.

Correct Answer: 2500 bags

Explanation: The maximum number of bags to be stored in two piles can be calculated using the formula: Number of bags = (Length × Breadth × Maximum height of piles × Number of piles) / Volume of one bag. Substituting the values, we get (15 m × 5.6 m × 2.70 m × 2) / (50 kg/bag), which is approximately 2500 bags.

Correct Answer: Batching

Explanation: Batching is the process of proper and accurate measurement of concrete ingredients (cement, aggregates, water) to achieve the desired uniformity of proportion in the concrete mix. It is a crucial step in ensuring the quality of the concrete.

Correct Answer: All of the above

Explanation: Proper batching ensures not only economy in the use of materials but also contributes to the durability and workability of concrete. It involves measuring and proportioning the ingredients accurately to achieve the desired properties in the finished concrete.

Correct Answer: Length 40 cm, breadth 25 cm, height 35 cm

Explanation: The dimensions of a form for measuring 35 liters of aggregates by volume are typically 40 cm in length, 25 cm in breadth, and 35 cm in height. This form is used to ensure accurate measurement during the batching process.

Correct Answer: 30 minutes

Explanation: The process of mixing, transporting, placing, and compacting concrete using ordinary Portland cement should ideally be completed within 30 minutes. This is to ensure that the concrete remains workable and can be placed and compacted effectively.

Correct Answer: Pumps

Explanation: For concreting of tunnel linings, where the transportation of concrete may involve difficult or confined spaces, concrete is often transported using pumps. Pumps are efficient in moving concrete over longer distances and through intricate structures.

Correct Answer: 150 cm

Explanation: To prevent segregation and achieve uniform compaction, the maximum height for placing concrete is typically limited to around 150 cm. Beyond this height, there is an increased risk of segregation and uneven distribution of aggregates.

Correct Answer: Vertical face – soffit of slab – soffit of beam

Explanation: The correct sequence for the removal of formwork is typically from the vertical faces first, followed by the soffit of the slab, and then the soffit of the beam. This sequence helps prevent damage to the concrete structure and ensures safety during the removal process.

Correct Answer: Seasoned soft wood

Explanation: Seasoned softwood is often suitable for formwork in construction work. Softwood, when properly seasoned, provides the necessary strength and durability required for formwork. It is commonly used due to its availability and cost-effectiveness.

Correct Answer: 18,900 liters

Explanation: The output of a concrete mixer can be calculated by multiplying the number of batches that can be produced in the effective working time by the capacity of each batch. In this case, (7 hours × 60 minutes/hour) / (3 minutes/batch) × 150 liters/batch = 18,900 liters.

Correct Answer: All of the above

Explanation: Too wet concrete can cause segregation, excessive laitance (formation of a thin layer of cement paste on the surface), and lower density. It is important to maintain the correct water-cement ratio to ensure the desired properties of the concrete.

Correct Answer: All of the above

Explanation: Non-uniform compaction of concrete can result in a porous and non-homogeneous structure, leading to reduced strength and durability. Uniform compaction is essential to achieve the desired properties and performance of the concrete.

Correct Answer: All of the above

Explanation: The compaction of concrete improves its density, strength, and durability. Adequate compaction ensures that the concrete mix is free from voids, leading to a denser and more durable finished product.

Correct Answer: Screed vibrator

Explanation: For compacting plum concrete road surfaces with a thickness less than 20 cm, a screed vibrator is commonly used. A screed vibrator is a specialized tool for leveling and compacting freshly placed concrete surfaces.

Correct Answer: Inferior to machine compaction

Explanation: The process of hand compaction of concrete is generally considered inferior to machine compaction. Hand compaction may result in uneven compaction and may not achieve the same level of density and uniformity as machine compaction.

Correct Answer: 28 days

Explanation: ISI (Indian Standards Institute) specifies the full strength of concrete to be measured after 28 days of curing. This is a standard practice in concrete testing, as most of the strength gain occurs during this period.

Correct Answer: Decreases the strength of concrete

Explanation: High temperatures can decrease the strength of concrete. Elevated temperatures can accelerate the rate of hydration, leading to rapid setting and reduced strength. It is important to consider temperature conditions during concrete placement and curing.

Correct Answer: Less liable to segregation

Explanation: Increased cohesiveness in concrete makes it less liable to segregation. Cohesive concrete has better particle distribution and can resist the separation of aggregates from the mortar during handling and transportation.

Correct Answer: All of the above

Explanation: To produce impermeable concrete, a combination of factors is essential, including thorough mixing, proper compaction, and adequate curing. Each of these factors contributes to achieving a dense and durable concrete with low permeability.

Correct Answer: Segregation

Explanation: The separation of coarse aggregates from the mortar in concrete during transportation is known as segregation. This can lead to uneven distribution of aggregates and affect the quality and appearance of the finished concrete.

Correct Answer: Bleeding

Explanation: The separation of water, sand, and cement slurry from freshly mixed concrete is known as bleeding. It involves the migration of excess water to the surface of the concrete, leaving a layer of water on top.

Correct Answer: All of the above

Explanation: Concrete is a composite material consisting of cement, aggregates (such as sand and gravel), water, and optional admixtures. All these components work together to form the hardened and durable material we know as concrete.

Correct Answer: All of the above

Explanation: Cement provides strength, durability, and water-tightness to concrete through the hydration process. The water-cement paste hardens due to hydration, and the cement binds the aggregates together, contributing to the overall strength and durability of concrete.

Correct Answer: All of the above

Explanation: Admixtures in concrete can serve various purposes. Some admixtures accelerate the hydration process, while others can enhance properties such as water resistance or acid resistance. Therefore, all the statements are correct.

Correct Answer: Lime

Explanation: The maximum percentage of the chemical ingredient in cement is that of lime. Lime is a primary component of cement and plays a crucial role in the hydration process, contributing to the strength of the hardened concrete.

Correct Answer: Magnesium oxide

Explanation: The minimum percentage of the chemical ingredient in cement is that of magnesium oxide. While magnesium oxide is present in cement, it is generally present in smaller amounts compared to other components like lime, silica, alumina, and iron oxide.

Correct Answer: Alkalis

Explanation: Efflorescence in cement is caused due to an excess of alkalis. When soluble alkalis are present in concrete and react with moisture, they can migrate to the surface and form white, powdery deposits known as efflorescence.

Correct Answer: Tricalcium silicate (c3s) has more resistance to sulfate attack

Explanation: Tricalcium silicate (C3S) is known for hydrating rapidly, generating more heat of hydration, and contributing to early strength development. However, it is not more resistant to sulfate attack. Sulfate resistance is typically associated with compounds like tricalcium aluminate (C3A).

Correct Answer: Increased lime content

Explanation: The rapid hardening of cement is achieved by increasing the lime content, particularly the content of tricalcium aluminate (C3A). This accelerates the hydration process, resulting in higher early strength.

Correct Answer: Rapid hardening cement

Explanation: Rapid hardening cement is commonly used for road pavements due to its ability to develop high strength at early ages. This allows for faster construction and earlier opening of roads to traffic.

Correct Answer: Low heat cement

Explanation: Low heat cement is suitable for massive concrete structures like dams because it generates less heat during hydration, reducing the risk of thermal cracking in large and thick sections.

Correct Answer: Blast furnace slag cement

Explanation: Blast furnace slag cement is not typically recommended for thin R.C.C. structures. It is more suitable for use in general construction where slower strength development is acceptable.

Correct Answer: All of the above

Explanation: The commercial names for white and colored cement can vary, and different manufacturers may use different brand names. Colocrete, Rainbow cement, and Silvicrete could be commercial names used in Nepal.

Correct Answer: 30%

Explanation: Pozzolana cement is manufactured using pozzolanic materials, and the percentage of clay in the pozzolanic material can be up to 30%.

Correct Answer: Aggregate

Explanation: Inert material in a cement concrete mix refers to the aggregate, which includes sand, gravel, or crushed stone. Water and cement are the active components in the mix.

Correct Answer: Size and shape of the container

Explanation: The bulk density of an aggregate depends on factors such as the size and shape of aggregates, specific gravity of aggregates, and grading of aggregates. It is independent of the size and shape of the container.

Correct Answer: 30 kg

Explanation: The water-cement ratio of concrete is given as 0.6, which means that for every 1 kg of cement, 0.6 kg of water is required. Therefore, for 50 kg of cement, the water required is 30 kg (50 kg * 0.6).

Correct Answer: Higher as compared to that by volume

Explanation: The water-cement ratio by weight is typically higher than that by volume because the density of cement is less than that of water. The water-cement ratio is a critical parameter in concrete mix design.

Correct Answer: 30 cm

Explanation: The standard height of a slump cone used in the slump test for measuring the workability of concrete is 30 cm.

Correct Answer: 6

Explanation: The minimum number of test specimens required for finding the tensile strength of concrete is typically 6. This allows for a statistically valid assessment of the material’s properties.

Correct Answer: 3

Explanation: The minimum number of test specimens required for finding the compressive strength of concrete is typically 3. However, more specimens may be tested for a more comprehensive evaluation.

Correct Answer: Does not set

Explanation: At the freezing point of water (0°C or 32°F), concrete does not set because the water in the mix freezes, preventing the normal hydration process. Freezing conditions can be detrimental to concrete during the setting and curing stages.

Correct Answer: It may corrode the reinforcement

Explanation: The use of sea water in concrete can lead to the corrosion of reinforcement due to the presence of chloride ions. While efflorescence and dampness are also possible issues, corrosion is a significant concern when using sea water in concrete.

Correct Answer: Decreases

Explanation: As the temperature rises, the setting time of cement tends to decrease. Higher temperatures accelerate the hydration process, leading to faster setting times.

Correct Answer: Less

Explanation: The water-cement (W/C) ratio in ferrocement is generally kept lower than that in normal concrete. This is done to achieve better workability and prevent excessive bleeding while maintaining the required strength.

Correct Answer: Troweling

Explanation: Troweling is the final operation of finishing floors. It involves using a trowel to smooth and compact the surface of freshly placed concrete.

Correct Answer: 0.38

Explanation: The minimum water-cement ratio required for full hydration of cement is approximately 0.38. This ratio ensures that there is sufficient water for complete hydration of the cement particles.

Correct Answer: Premature hardening

Explanation: Flash set in ordinary Portland cement paste refers to the phenomenon of premature hardening before normal setting time. It is not a desirable property.

Correct Answer: Reaction of tricalcium aluminate with water

Explanation: The flash set of Portland cement is primarily caused by the rapid reaction of tricalcium aluminate (C3A) with water, leading to premature hardening.

Correct Answer: Sieve analysis/air permeability

Explanation: The fineness of cement is commonly determined by sieve analysis or air permeability methods. The specific surface area of the cement particles is a crucial factor in assessing fineness.

Correct Answer: Le Chatelier’s apparatus

Explanation: The soundness of Portland cement is determined by the Le Chatelier’s apparatus test. It measures the expansion of cement when subjected to a standard amount of autoclave pressure.

Correct Answer: Both (a) and (b) above

Explanation: The soundness test can indicate unsoundness in cement due to the presence of free lime or excess magnesium oxide. Both factors can lead to expansion and cracking.

Correct Answer: 2%

Explanation: The maximum permissible concentration of magnesia in ordinary Portland cement is typically limited to around 2% to avoid adverse effects on the properties of the cement.

Correct Answer: Less than 1.5%

Explanation: The insoluble residue in cement, often referred to as loss on ignition (LOI), is typically required to be less than 1.5%. This parameter indicates the presence of impurities in the raw materials used for cement manufacturing.

Correct Answer: All of the above

Explanation: The addition of pozzolana to cement can result in increased curing time, reduced heat of hydration, and improved resistance to permeability. Pozzolanic materials like fly ash and silica fume are commonly used for these benefits.

Correct Answer: Quick-setting material

Explanation: Gypsum is added to control the setting time of cement. It acts as a retarder, slowing down the setting of the cement to allow sufficient time for proper placement and finishing.

Correct Answer: Moisture content

Explanation: The bulking of aggregates occurs due to an increase in volume caused by the presence of moisture on the surface of the aggregate particles. This increase in volume can affect the mix proportions in concrete.

Correct Answer: Silicious material

Explanation: Pozzolana is a siliceous or siliceous and aluminous material that, when combined with lime in the presence of moisture, forms cementitious compounds. It is commonly used as a supplementary cementitious material in concrete.

Correct Answer: 0.0347 m³

Explanation: The volume of one bag of cement (50 kg) is approximately 0.0347 cubic meters. This value is based on the density of ordinary Portland cement, which is around 1440 kg/m³.

Correct Answer: 45 m

Explanation: Expansion joints in buildings are generally provided when the length of concrete or structural elements exceeds a certain limit. The common practice is to provide expansion joints for lengths exceeding 45 meters to accommodate thermal movements and prevent cracking.

Correct Answer: Mild steel

Explanation: Concrete is commonly reinforced using bars made of mild steel. The use of mild steel reinforcement provides strength and ductility to the concrete, allowing it to withstand tensile forces.

Correct Answer: 2.5 t/m³

Explanation: The unit weight of Reinforced Cement Concrete (RCC) is commonly taken as 2.5 tons per cubic meter (t/m³). This value may vary slightly depending on the mix proportions and the density of the materials used.

Correct Answer: Style

Explanation: In the context of a shutter frame, the vertical side member is referred to as the “style.” The style provides support to the shutter and contributes to the overall structure of the frame.

Correct Answer: Mullion

Explanation: The vertical member running through the middle of a shutter frame is known as the “mullion.” The mullion provides additional support and stability to the frame, especially in the case of larger openings.

Correct Answer: Horn

Explanation: The projections of the head or sill of a door or window frame, often designed for decorative or functional purposes, are known as “horns.” Horns may be present at the top or bottom of the frame.

Correct Answer: 38 mm

Explanation: The maximum thickness of door shutters provided in doors can vary, but a common thickness is 38 mm (approximately 1.5 inches). This thickness provides the necessary strength and durability for typical door applications.

Correct Answer: Rebate

Explanation: A cut or step in the frame of a door to receive the shutter is known as a “rebate.” The rebate provides a space for the door shutter to fit securely and helps in creating a tight seal.

Correct Answer: 1 cm

Explanation: The thickness of a rebate is typically kept around 1 cm (10 mm). The precise dimension may vary based on design and construction requirements.

Correct Answer: Stop

Explanation: A wooden block fixed on the back side of a door frame on its post is known as a “stop.” The stop helps prevent the door from swinging too far into the room and provides support.

Correct Answer: Cleat

Explanation: A wooden block hinged on the post outside a door is known as a “cleat.” Cleats are used to secure doors, especially in the open position, preventing them from swinging too far.

Correct Answer: Pivoted window

Explanation: A small window in which shutters are allowed to swing around pivots fixed to the window frame is known as a “pivoted window.” Pivoted windows typically open by rotating around a vertical or horizontal axis.

Correct Answer: Dormer window

Explanation: The window provided on a sloping roof of a building is called a “dormer window.” Dormer windows are often used to bring light into attic spaces or rooms located within the roof structure.

Correct Answer: Lantern window

Explanation: The window provided in a flat roof of a room is known as a “lantern window.” Lantern windows are designed to allow natural light into the space below and may be part of a larger skylight or roof opening.

Correct Answer: Battened & ledged door

Explanation: A gate (door) without importance is typically referred to as a “battened & ledged door.” This type of door consists of horizontal battens (boards) held together by vertical ledges. It is a simple and commonly used door design.

Correct Answer: Screeding

Explanation: Bringing the floor to a true level surface by means of screeds is known as “screeding.” Screeds are typically used to level and finish a concrete floor or other surfaces.

Correct Answer: Terrazzo floor

Explanation: A floor constructed with special aggregate of 3 mm marble chips mixed with white and colored cement is called a “Terrazzo floor.” Terrazzo flooring is known for its durability and attractive appearance.

Correct Answer: Cork flooring

Explanation: Cork flooring is suitable for noiseless situations such as theaters, churches, libraries, etc., due to its sound-absorbing properties.

Correct Answer: Granolithic flooring

Explanation: Granolithic flooring is suitable to resist heavy wear and provides an attractive appearance. It is a type of flooring made from a mixture of cement, sand, and crushed rock.

Correct Answer: Timber flooring

Explanation: Timber flooring is preferred for a dancing hall due to its smooth surface and comfortable feel. It is commonly used in areas where a resilient and aesthetically pleasing floor is desired.

Correct Answer: Sloping member that supports the step in a stair

Explanation: In stairs, stringers are the sloping members that support the steps (treads) and risers. They provide structural support to the staircase.

Correct Answer: Threshold

Explanation: The arrangement of steps provided from the ground level to the plinth level is known as the “threshold.”

Correct Answer: Straight step having parallel width of tread

Explanation: In stairs, a flier is a straight step having parallel width of tread. It is a basic step without any change in direction.

Correct Answer: Flight

Explanation: A series of steps without any platform in a stair is called a “flight.” It represents a continuous series of steps between landings.

Correct Answer: 17

Explanation: The number of treads (steps) can be calculated by dividing the total floor height by the riser height. In this case, 2.70 m / 0.15 m = 18 treads. However, the number of risers is one less than the number of treads, so it would be 17 treads.

Correct Answer: Scotia

Explanation: A moulding provided under nosing to beautify the elevation of the step is known as “scotia.” Scotia is a concave moulding used for decorative purposes.

Correct Answer: Baluster

Explanation: The vertical member fixed between steps and handrail in a stair is known as a “baluster.” It provides support and serves as a decorative element.

Correct Answer: Newel post

Explanation: The vertical member provided at the top and bottom ends of a flight supporting the handrail is called a “newel post.” It is a structural element that provides stability to the handrail.

Correct Answer: Landing

Explanation: The platform at the end of the series of steps is known as the “landing.” It provides a flat surface for users to rest or change direction in the staircase.