Construction Test 3 — Questions and Answers

Question 1: The wedge-shaped bricks used to create the arch ring are known as

Voussoirs (Correct answer)
Spandrils
Soffits
Haunches

Correct answer: Voussoirs

Voussoirs are the fundamental components of an arch. They are precisely cut, wedge-shaped blocks, usually made of stone or brick, that form the curved structure. These blocks are arranged with radiating joints, transferring the compressive forces of the arch outwards to its supports, with the central keystone locking them into place.

Question 2: For isolated foundations on clayey soils, the overall settlement should not exceed _______.

30 mm
65 mm (Correct answer)
70 mm
120 mm

Correct answer: 65 mm

For isolated foundations built on clayey soils, the maximum permissible total settlement is generally limited to 65 mm. This standard is established to prevent excessive structural damage, tilting, or functional issues within the building caused by uneven or significant ground movement. Different soil types and foundation designs have specific settlement criteria.

Question 3: _______ is the name for the foundation, which consists of a thick slab of reinforced cement covering the entire region to support highly concentrated structural loads.

Raft footing (Correct answer)
Strap footing
Combined footing
All of the options are correct

Correct answer: Raft footing

A raft footing, also known as a mat foundation, is a large, continuous slab of reinforced concrete that covers the entire footprint of a structure. This type of foundation is employed when individual footings would cover more than half the building area, or when the soil's bearing capacity is low. It effectively distributes heavy, concentrated structural loads over a much larger area, reducing the pressure exerted on the underlying soil.

Question 4: The depth of exploration for each floor (or storey) of a building should be _______.

1 meter
3 meters (Correct answer)
10 meters
12 meters

Correct answer: 3 meters

The depth of soil exploration for a building's foundation is critical for understanding the subsurface conditions. A common guideline for preliminary investigations suggests a minimum exploration depth of 3 meters for each floor or storey of the building. This ensures that the investigation extends sufficiently below the proposed foundation level to identify any problematic soil layers, groundwater, or geological features that could affect the structure.

Question 5: Choose the appropriate statement from the list below:

Curing concrete is necessary for optimal cement compaction.
The index value known as fineness modulus expresses the relative sizes of both coarse and fine aggregates. (Correct answer)
Both compression and tension are equally powerful forces for plain cement concrete.
Slump test is used to evaluate the strength of concrete.

Correct answer: The index value known as fineness modulus expresses the relative sizes of both coarse and fine aggregates.

The fineness modulus is an empirical index value used in concrete technology to describe the average size of aggregate particles. It is derived from the sieve analysis of both coarse and fine aggregates, providing a quick measure of their overall fineness or coarseness. This value is crucial for concrete mix design, helping to ensure optimal workability, strength, and economy of the mix.

Question 6: A water-logged soil's ability to support weight can be increased by:

Increasing the foundation's depth
Grouting
Soil draining (Correct answer)
Increasing soil density

Correct answer: Soil draining

Water-logged soil has significantly reduced bearing capacity because the water fills the soil pores, decreasing the effective stress between soil particles. Draining the soil removes this excess water, thereby increasing the effective stress and improving its ability to support loads. This process directly addresses the root cause of the weakened bearing capacity in saturated soils.

Question 7: _______ refers to the posture of a brick when it is lay on its side in a 9 cm by 9 cm square with its frog in the vertical plane.

Brick without end
Brick held vertically
Brick on edge
Brick on end (Correct answer)

Correct answer: Brick on end

When a brick is laid 'on end,' it means it is positioned with its smallest face (typically 9 cm x 9 cm) exposed, and its longest dimension (length) oriented vertically. In this orientation, the frog (the indentation on one of the larger faces) would indeed be in a vertical plane. This laying style is often used for specific decorative patterns, paving, or certain structural elements.

Question 8: _______ is made from marble chips that range in size from 4 to 6 mm.

Reinforced marble floor
Granite floor
Terrazzo floor (Correct answer)
Marble floor

Correct answer: Terrazzo floor

Terrazzo flooring is a composite material renowned for its durability and aesthetic appeal. It is typically made by mixing chips of marble, quartz, granite, or glass, often ranging in size from 4 to 6 mm, with a cementitious or polymeric binder. This mixture is then poured, cured, ground, and polished to create a smooth, seamless, and decorative surface.

Question 9: Only after ______ may the form work, including the supports, be removed from the beams.

1 week
2 weeks (Correct answer)
3 weeks
1 month

Correct answer: 2 weeks

The removal of formwork, especially for structural elements like beams that carry significant loads, is critical and depends on the concrete's strength gain. For beams, a minimum curing period of 14 days (2 weeks) is generally recommended before removing the formwork and supports. This duration ensures the concrete has achieved sufficient strength to safely support its own weight and any imposed loads without excessive deflection or damage.

Question 10: _______ is a type of mortar that uses both cement and lime as binding agents.

Fire resistant mortar
Gauged mortar (Correct answer)
Lime mortar
Cement mortar

Correct answer: Gauged mortar

Gauged mortar is a versatile type of mortar that combines both cement and lime as binding agents, along with sand and water. The inclusion of cement enhances the mortar's strength and accelerates its setting time, while lime improves its workability, plasticity, and water retention. This combination provides a balanced set of desirable properties for various masonry applications.

Question 11: The minimal depth of foundations, according to Rankine's formula, is ______.

(P/w) × [(1 + sin φ)/(1 - sin φ)]²
(P/2w) × [(1 - sin φ)/(1 + sin φ)]²
(P/w) × [(1 - sin φ)/(1 + sin φ)]² (Correct answer)
(P/w) × [(1 + sin φ)/(1 - sin φ)]²

Correct answer: (P/w) × [(1 - sin φ)/(1 + sin φ)]²

Rankine's formula provides a theoretical minimum depth for foundations to ensure stability against lateral soil movement. The formula is Df = (P/w) × [(1 - sin φ)/(1 + sin φ)]², where Df is the minimum depth, P is the safe bearing capacity of the soil, w is the unit weight of the soil, and φ is the angle of repose or internal friction of the soil. This calculation helps prevent the soil from yielding laterally under the foundation's load.

Construction Test 3

The wedge-shaped bricks used to create the arch ring are known as