Correct Answer: D. Reinforced brickwork
Solution:
Reinforced brickwork incorporates steel reinforcement (bars or mesh) within the mortar joints or in cavities. This reinforcement provides significant tensile strength, which unreinforced masonry lacks. During an earthquake, structures are subjected to lateral forces that induce tension. The steel reinforcement helps the wall resist these forces, preventing catastrophic brittle failure and providing much greater ductility and overall earthquake resistance compared to other unreinforced masonry types.
Correct Answer: C. Cement : Sand
Solution:
In cement mortar mixes, the ratio represents the proportion of binder (cement) to fine aggregate (sand) by volume. A 1:4 ratio is a common mix for plastering, meaning it consists of 1 part cement to 4 parts sand.
Correct Answer: C. Steel
Solution:
Steel formwork (shuttering) is highly durable, strong, and can be reused hundreds of times with very little maintenance. Unlike timber, it does not absorb moisture, warp, or shrink, making it a long-lasting and economical choice for large projects.
Correct Answer: B. mastic asphalt
Solution:
Mastic asphalt is a voidless, dense, and highly durable material created by heating asphalt and mixing it with sand and mineral fillers. It is widely used for waterproofing roofs, floors, and tanking.
Correct Answer: B. 30
Solution:
A standard modular brick has a nominal size of 20 cm x 10 cm x 10 cm (including mortar). A one-and-a-half brick wall is constructed with one brick's length and one brick's width. Therefore, the thickness is the length of one brick (20 cm) plus the width of one brick (10 cm), totaling 30 cm.
Correct Answer: B. There is a gain of compressive strength by the replacement of less than 25% of cement by hydrated lime.
Solution:
This statement is incorrect. Replacing cement (the primary strength-giving component) with hydrated lime will generally decrease the compressive strength of the mortar, although it improves workability, water retention, and elasticity. Lime does not contribute to strength in the same way cement does.
Correct Answer: A. Abut
Solution:
The term "abut" means to border on or adjoin. In building regulations, a property or wall that is directly on the street boundary is said to abut the street.
Correct Answer: B. 3.5 N/mm²
Solution:
Indian Standard IS 2185 (Part 1) specifies the requirements for concrete masonry units (blocks). For these units to be classified as load-bearing, they must have a minimum average compressive strength of 3.5 N/mm² on the net area.
Correct Answer: A. Cement concrete
Solution:
Materials used for damp-proofing courses (DPC) can be categorized as rigid or flexible. Cement concrete (typically a rich mix like 1:1.5:3) is a rigid DPC material. Bitumen felts, polythene sheets, and mastic asphalt are all examples of flexible DPC materials.
Correct Answer: B. High drying shrinkage
Solution:
Adding lime to cement mortar improves its properties by increasing workability and water retention, which leads to low drying shrinkage. Therefore, high drying shrinkage is a disadvantage, not an advantage of composite mortar.
Correct Answer: C. Bull mark
Solution:
A bull mark (or dot) is a small patch of plaster of the desired thickness that is applied to the surface before general plastering begins. These marks are set out across the wall to act as guides, ensuring a uniform and even thickness of the final plaster coat.
Correct Answer: A. Rough
Solution:
A rough surface is essential before plastering as it provides a better mechanical key or grip for the plaster to adhere to. A smooth surface can lead to poor bonding and potential detachment of the plaster layer.
Correct Answer: C. Pozzolana
Solution:
Cement, gypsum, and lime are all primary binding materials used to make different types of plaster. Pozzolana, on the other hand, is a siliceous and aluminous material which in itself possesses little or no cementitious value but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide to form compounds possessing cementitious properties. It is an additive, not a primary plaster type.
Correct Answer: D. Undercoat, 10-15
Solution:
The first coat of plaster applied to a surface is known as the undercoat or render coat. Its purpose is to cover irregularities in the background surface. Its typical thickness is between 10-15 mm to provide a true and level base for subsequent coats.
A. Mud plastering does not require curing.
B. Mud plastering requires curing.
C. It depends on the situation.
Correct Answer: A. Only A
Solution:
Statement A is true. Mud plaster hardens by drying (evaporation of water), not by a chemical reaction like cement plaster. Curing is the process of keeping cement-based materials moist to allow for hydration, the chemical reaction that gives them strength. Since mud plaster does not undergo hydration, it does not require curing.