Miscellaneous Material MCQ Quiz - Objective Question with Answer for Miscellaneous Material - Download Free PDF

Explanation:

• A plunging fold as one where the fold axis is inclined (not horizontal).

• This results in:

  • Outcrop patterns that appear curved or V-shaped on geological maps.

  • A distinct difference from horizontal folds, which produce straight bands.

• Plunging folds often form due to complex tectonic stress, especially during multi-phase deformation.

• Symmetrical limbs or steep axial planes are not exclusive features of plunging folds.

Explanation:

• A normal fault is defined as a type of dip-slip fault where:

  • The hanging wall (block above the fault) moves downward.

  • The footwall (block below the fault) stays in place or moves upward.

• This occurs due to tensional forces, causing the crust to stretch and thin.

• Normal faults are commonly found in rift zones and extensional tectonic settings.

• Compressional stress leads to reverse or thrust faults, not normal faults.

Explanation:

• Joints are natural fractures in rocks without displacement, distinct from faults.

  • Spacing (distance between joints) and orientation (angle and direction) significantly influence:

    • Rock stability, especially in excavations, slopes, and foundations.

    • Water seepage and erosion patterns.

• Closely spaced joints reduce the block size and can increase the risk of failure under load.

• Mineral composition and color matter less in structural stability than joint geometry.

• While weathering degrades strength, joint properties directly govern structural behavior.

Explanation:

• Plasticity refers to the soil’s ability to undergo deformation without cracking or breaking.

• As per the textbook:

  • It is largely dependent on the amount and type of clay minerals present.

  • Montmorillonite, for example, has high plasticity, while kaolinite has lower plasticity.

• Clay minerals have a high surface area and adsorb water, allowing them to exhibit plastic behavior.

• Silt and sand lack cohesion and exhibit little to no plasticity.

• Organic matter may affect compressibility but not plasticity directly.

Explanation:

• Capillary action is the ability of soil to draw water upward from the water table into the unsaturated zone.

• It occurs due to:

  • Adhesive forces between water molecules and soil particles.

  • Surface tension pulling water into fine pores.

• Finer soils like clay and silt exhibit greater capillary rise due to smaller pores.

• The textbook emphasizes that this process plays a crucial role in:

  • Moisture availability for plants.

  • Corrosion risk in shallow foundations and underground structures.

• Gravity causes downward flow, not upward; pressure gradient drives saturated flow, not capillarity.

Concept:

Impact test:

Impact test is used to determining the toughness of stone, it is performed in an Impact Test Machine as followed:

1. A cylinder of diameter 25mm and height 25mm is taken out from the sample of stones.
2. It is then placed on the cast iron anvil of the machine.
3. A steel hammer of weight 20N is allowed to fall axially in a vertical direction over the specimen.
4. The height of the first blow is 1 cm, that of the second blow is 2 cm, that of the third blow is 3 cm, and so on.
5. Blow at which specimen breaks is noted. If it is an nth blow, ‘n’ represents the toughness index of stone.

Explanation:

Slaking is the process in which quick lime reacts with water, during this reaction, it swells, cracks, and falls out as calcium hydroxide.

\(\underbrace {CaO}_{\begin{array}{*{20}{c}} {Quick} \\ {lime} \end{array}} + {H_2}O\xrightarrow{{Slaking}}\underbrace {Ca{{\left( {OH} \right)}_2}}_{\begin{array}{*{20}{c}} {Hydrate} \\ {lime} \end{array}} + Heat\)

Explanation:

Characteristics of good building stones are:

• Compressive strength > 1000 kg/cm2 or 100 N/mm2
• High durability and coefficient of hardness > 14
• Stones should be well seasoned before putting into use.
• Specific gravity > 2.7
• Toughness Index > 13
• Low water absorption

Explanation:

(i) The process of giving a proper size, shape, and finish to the roughly broken stones as obtained from the quarry is known as “Dressing of stone” and is carried out for the following purposes:

• To get the desired appearance from stone work.
• to make the transport from quarry easy and economical.
• to suit to the requirements of stone masonry.
• to take advantage of local mean near quarry who are trained for such type of work, etc.

(ii) The process of extraction of suitable stones from their natural rock beds or layers is commonly called Quarrying of Stones

(iii) Stones obtained from the quarries are very rough and irregular in shape and quite bulky in size and weight

(iv) The dressing of stone is done immediately after quarrying.

(v) Seasoning of stone means removal of moisture from stone. seasoning is performed by placing the stones in sundried conditions.

Explanation: 

Concept:

Dorry abrasion test: 

• The test gives a measure of the resistance of aggregate to surface wear by abrasion. 
• Inadequate abrasion resistance of road-surfacing aggregates means an early loss of the texture depth required to maintain high-speed skidding resistance.
• Coefficient of hardness is calculated from Dorry abrasion test and it indicates resistance against external weathering of aggregates.

• \(Coefficient\,\,of\,\,Hardness= \,20\,-\,\frac{Loss\,\,in\,\,weight\,(gm)}{3}\)

• For good aggregate, it should not be less than 17.

• For medium quality aggregate, it is between 14 to 17.

Solution: given, loss in weight of aggregates = 21 gm, 

∴ \(Coefficient\,\,of\,\,Hardness= \,20\,-\,\frac{Loss\,\,in\,\,weight\,(gm)}{3} =\,20\,-\,\frac{21}{3} =\,\, 13\)

Explanation:

Asbestos is natural mineral, which consists of silicate of calcium and magnesium found in the form of very thin fibres.

Characteristics of Asbestos:

• They are light in weight and fire-resistant.
• It has low water permeability hence less porous.
• It is brown, grey, and white in colour.
• It is resistant to acids and alkalis.
• Its specific gravity is 3.10.
• It has excellent heat and electric insulation.
• They do not require any protective paint.
• Asbestos cement is widely used in the manufacturing of roofing slates and tiles.
• These sheets are widely used in industries, factories, cinemas, auditoriums etc. 

Explanation:

Splitting Tension Test on Rocks

• This is also called as Brazilian test. In this test, the specimen is split along the diametric plane by applying load.
• The specimen having the length to diameter ratio of unity when loaded on its side it splits along the diameter and parallel to the cylindrical axis. The horizontal stresses perpendicular to the loaded diameter are uniform and tensile. The tensile stress is given by

\({\sigma _t} = \frac{{2P}}{{\pi dt}}\)

where d = diameter, t = thickness or length of the cylinder, p = applied load.

Important Points

IS: 10082-1981 recommends that the diameter of the specimen should be at least 45 mm and the thickness of the disc shall be approximately equal to half the diameter.

The load should be applied at the rate of 0.2 KN/sec and the load should be measured at least to an accuracy of 1 %.

Explanation:

Laterite is claystone with a vesicular structure.

Vesicular texture

It is a rock texture characterized by a rock being pitted with many cavities (known as vesicles) at its surface and inside.

Among the given options, Laterite is the only clayey stone and it is formed from a wide variety of rocks under slow chemical weathering.

Because of this weathering, it has a vesicular appearance.

Hence among the given options, option (1) is the most appropriate answer

Laterite:

It is sandy claystone containing a high percentage of iron oxide

Its specific gravity varies from 2 to 2.2

Crushing strength = 1.8 to 32 kg/cm2

Explanation:

Terracotta:

• The most common uses for earthenware are roofing tiles and terracotta pots and dinnerware.
• Terracotta is used in the manufacturing of water and waste water pipes, roofing tiles, bricks, and surface embellishment in building construction.

Porcelain:

• Porcelain is a ceramic material made by heating substances, generally including materials such as kaolinite, in a kiln to temperatures between 1,200 and 1,400 °C. 
• Porcelain is used for tableware, decorative objects, laboratory equipment, and electrical insulators like switches, sockets, tubes, etc.

Concept:

Hardness:

• It is the ability of the material to resist scratch.
• It is measured by Mohs hardness test in which the mineral substances of known variation in hardness are used to scratch the rock.
• The following table shows the minerals and their mohs value -

Additional Information

The following listed test is used for aggregates -

Confusion Points

• Abrasion test is used for aggregates while Mohs scale test is used for stones/rocks.