Building Stones MCQs – Part 3
20 questions. Tap an option to check it instantly, then read the solution.
Answer: B. argillaceous rocks
Based on their chemical composition, rocks are classified by their dominant minerals. Rocks in which alumina or clay (argil) are the main constituents are known as argillaceous rocks. Examples include slate and laterite.
Answer: C. cleavage
Cleavage is the property of a mineral or rock to break along specific planes of weakness, producing smooth, flat surfaces. This is different from fracture, which is an irregular break. Slate is a classic example of a rock with excellent cleavage.
Answer: C. talc
Hardness is measured on the Mohs scale from 1 (softest) to 10 (hardest). Talc is the defining mineral for the softest end of the scale, with a rating of 1. The other options are significantly harder.
Answer: B. argillaceous rock
Laterite is a type of rock and soil rich in iron and aluminum, formed in hot and wet tropical areas. Chemically, its primary constituent is clay/alumina, which classifies it as an argillaceous rock.
Answer: B. 10%
While a very good quality stone should absorb less than 5% water, the general limit for rejecting a building stone is when its water absorption exceeds 10% of its dry weight. High water absorption indicates higher porosity, which can lead to lower strength and poor durability.
Answer: D. all the above
Limestone fits all of these classifications:
- Aqueous rock: It is formed from the deposition of sediments in water.
- Sedimentary rock: This is its primary geological classification based on its formation from sediments.
- Stratified rock: This is a physical classification, as limestone is formed in layers (strata).
Therefore, "all the above" is the correct answer.
Answer: C. monomineralic
The term for a rock composed of a single mineral is monomineralic. Conversely, a rock composed of multiple minerals is called polymineralic.
Answer: A. intrusive igneous rock
Pegmatite is a type of intrusive igneous rock known for its extremely large crystals. It forms during the final stages of magma crystallization, where the remaining water-rich melt allows crystals to grow to very large sizes.
Answer: B. hardness test of stone
Dorry's testing machine is used to determine the hardness or resistance to abrasion of stones. A cylindrical stone sample is subjected to the abrasive action of sand under a specified pressure.
Answer: B. hard
Rubble masonry is constructed from rough, undressed stones. Since it is a load-bearing construction, the stones must be hard and durable to ensure the strength and stability of the wall.
Answer: D. 45%
Dolomite is a specific type of limestone that is rich in magnesium. By definition, for a limestone to be classified as dolomite, it must contain a significant amount of magnesium carbonate, which can be up to 45%.
Answer: D. 17
The coefficient of hardness, determined using Dorry's testing machine, measures a stone's resistance to wear and abrasion. For stones used in road construction, which are subjected to heavy traffic, a high resistance to wear is critical. A coefficient of hardness greater than 17 is required for such applications.
Answer: C. extrusive igneous rock
Basalt is a type of igneous rock that forms from the rapid cooling of lava at or near the Earth's surface. Because it forms on the surface, it is classified as an extrusive igneous rock.
Answer: C. igneous rocks
Granite is a classic example of an igneous rock. Specifically, it is an intrusive igneous rock, meaning it formed from the slow cooling of magma deep beneath the Earth's surface.
Answer: E. All the above
Wedging is a careful quarrying method used for extracting valuable dimension stone without shattering it. It's particularly suitable for stratified rocks (those in layers) that are soft or costly. All the options listed—laterite, marble, limestone, and sandstone—are types of stratified rocks for which this careful extraction method is appropriate to get usable blocks.
Answer: C. white
Statuary marble is a high-quality marble prized by sculptors for its purity, fine grain, and translucence. The most famous and sought-after statuary marble, such as Carrara marble from Italy, is pure white.
Answer: C. both (a) and (b)
Placing stratified stones with their natural bedding planes parallel to the direction of the load is incorrect practice. The load can easily cause the stone to split along these weak planes. Furthermore, these exposed layers can more easily absorb moisture, leading to faster decay and deterioration.
Answer: C. 100
Crushing strength is a critical property for building stones, especially those used in load-bearing structures. A good quality building stone should have a crushing strength of at least 100 MPa (MegaPascals) to ensure it can safely support the loads imposed on it.
Answer: A. Compact sandstone
Compact sandstone has the best fire-resisting properties because its quartz grains are cemented by silica, which is highly resistant to heat. Other rocks, like those containing calcium carbonate (marble) or clay (shale), tend to crack or decompose at high temperatures.
Answer: C. hard steel ball
The Brinell hardness test involves indenting the test material with a hard steel ball of a standard diameter under a specific load. The diameter of the resulting indentation is then measured to determine the material's hardness. Diamond cones are used in other tests like the Rockwell test.