Please keep at least one language enabled. || కనీసం ఒక భాషను ఎంచుకోండి.
Question 1
ప్రశ్న 1
Which statement best describes durability of a natural building stone?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Durability describes the capacity of stone to remain serviceable over time under its actual environmental and loading conditions.
• Deteriorating influences may include moisture, salts, temperature changes, chemical attack, mineral alteration and repeated wetting and drying.
• Compressive strength contributes to performance but does not by itself establish resistance to long-term environmental deterioration.
• Workability and appearance are separate characteristics and cannot substitute for durability assessment.
• Therefore Option A gives the appropriate engineering meaning of durability.
• Deteriorating influences may include moisture, salts, temperature changes, chemical attack, mineral alteration and repeated wetting and drying.
• Compressive strength contributes to performance but does not by itself establish resistance to long-term environmental deterioration.
• Workability and appearance are separate characteristics and cannot substitute for durability assessment.
• Therefore Option A gives the appropriate engineering meaning of durability.
వివరణ:
Question 2
ప్రశ్న 2
Which of the following is primarily a physical weathering mechanism in building stone?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Repeated heating and cooling can cause different minerals within a stone to expand and contract by different amounts.
• The resulting internal stresses may progressively produce microcracks without requiring a chemical change in the minerals themselves.
• This mechanism is therefore principally physical or mechanical weathering.
• Calcite dissolution, mineral oxidation and feldspar alteration involve chemical reactions and are classified as chemical weathering mechanisms.
• Hence Option A is the only predominantly physical mechanism among the alternatives.
• The resulting internal stresses may progressively produce microcracks without requiring a chemical change in the minerals themselves.
• This mechanism is therefore principally physical or mechanical weathering.
• Calcite dissolution, mineral oxidation and feldspar alteration involve chemical reactions and are classified as chemical weathering mechanisms.
• Hence Option A is the only predominantly physical mechanism among the alternatives.
వివరణ:
Question 3
ప్రశ్న 3
In a cold climate where a porous stone repeatedly becomes saturated and then freezes, what is the principal durability concern?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Water entering accessible pores and cracks can freeze when the temperature falls sufficiently below the freezing point.
• Formation of ice and associated hydraulic or crystallization pressures can impose stresses on the surrounding stone matrix.
• Repeated freeze-thaw cycles may progressively enlarge existing cracks and cause scaling, granular disintegration or spalling in susceptible stones.
• The risk depends strongly on saturation, pore geometry, stone strength and climatic exposure rather than merely on the presence of pores.
• Therefore Option A correctly describes the relevant deterioration mechanism.
• Formation of ice and associated hydraulic or crystallization pressures can impose stresses on the surrounding stone matrix.
• Repeated freeze-thaw cycles may progressively enlarge existing cracks and cause scaling, granular disintegration or spalling in susceptible stones.
• The risk depends strongly on saturation, pore geometry, stone strength and climatic exposure rather than merely on the presence of pores.
• Therefore Option A correctly describes the relevant deterioration mechanism.
వివరణ:
Question 4
ప్రశ్న 4
Why can repeated crystallization of soluble salts within the pores of a building stone cause serious deterioration?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Dissolved salts can be transported into a porous stone by rainwater, groundwater, capillary moisture or other water sources.
• When water evaporates, salts may crystallize within pores and near surfaces.
• Repeated crystallization and hydration changes can generate stresses capable of exceeding the local tensile resistance of the stone fabric.
• Progressive damage may appear as powdering, scaling, flaking or loss of grains and is therefore more than a cosmetic problem.
• Option A correctly explains the engineering significance of salt crystallization.
• When water evaporates, salts may crystallize within pores and near surfaces.
• Repeated crystallization and hydration changes can generate stresses capable of exceeding the local tensile resistance of the stone fabric.
• Progressive damage may appear as powdering, scaling, flaking or loss of grains and is therefore more than a cosmetic problem.
• Option A correctly explains the engineering significance of salt crystallization.
వివరణ:
Question 5
ప్రశ్న 5
A porous stone wall repeatedly becomes wet and then dries. Why can these moisture cycles contribute to deterioration even when freezing does not occur?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Wetting and drying cause changes in moisture content within the stone and may repeatedly activate several deterioration processes.
• Soluble salts can migrate during wetting and crystallize during drying, while clay-bearing or otherwise moisture-sensitive constituents may undergo dimensional changes.
• Differential movement between minerals or zones of the stone can generate repeated internal stresses.
• The severity depends on mineralogy, pore structure, salt content and the magnitude and frequency of moisture cycling.
• Therefore Option A correctly describes why wet-dry cycling can be important even without frost.
• Soluble salts can migrate during wetting and crystallize during drying, while clay-bearing or otherwise moisture-sensitive constituents may undergo dimensional changes.
• Differential movement between minerals or zones of the stone can generate repeated internal stresses.
• The severity depends on mineralogy, pore structure, salt content and the magnitude and frequency of moisture cycling.
• Therefore Option A correctly describes why wet-dry cycling can be important even without frost.
వివరణ:
Question 6
ప్రశ్న 6
A calcitic limestone facade is exposed for many years to strongly acidic runoff. Which deterioration mechanism is most directly expected?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Calcitic limestone contains calcium carbonate as a major constituent.
• Acidic water reacts with carbonate minerals and can dissolve or alter the exposed stone surface.
• Continued attack can result in loss of detail, roughening, surface recession and weakening of susceptible zones.
• This is a chemical deterioration mechanism rather than a purely mechanical abrasion process.
• Therefore Option A gives the expected response of carbonate stone to sustained acidic runoff.
• Acidic water reacts with carbonate minerals and can dissolve or alter the exposed stone surface.
• Continued attack can result in loss of detail, roughening, surface recession and weakening of susceptible zones.
• This is a chemical deterioration mechanism rather than a purely mechanical abrasion process.
• Therefore Option A gives the expected response of carbonate stone to sustained acidic runoff.
వివరణ:
Question 7
ప్రశ్న 7
A roofing or facing stone contains appreciable pyrite or other readily oxidizable iron-sulphide inclusions. What durability problem may develop during weather exposure?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Iron-sulphide minerals such as pyrite can oxidize when exposed to oxygen and moisture.
• The resulting products may produce yellow, brown or rust-coloured staining on the stone surface.
• Mineral alteration can also be accompanied by local volume changes and formation of secondary products that contribute to deterioration.
• The significance depends on the quantity, distribution and stability of the inclusions and the environmental exposure.
• Hence Option A correctly identifies the durability concern.
• The resulting products may produce yellow, brown or rust-coloured staining on the stone surface.
• Mineral alteration can also be accompanied by local volume changes and formation of secondary products that contribute to deterioration.
• The significance depends on the quantity, distribution and stability of the inclusions and the environmental exposure.
• Hence Option A correctly identifies the durability concern.
వివరణ:
Question 8
ప్రశ్న 8
Why can biological growth such as plant roots, mosses or lichens contribute to deterioration of exposed stone?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Biological colonization can keep portions of a stone surface damp for longer periods and thereby alter the local moisture regime.
• Roots growing into joints or cracks may exert mechanical pressure and enlarge existing discontinuities.
• Some organisms also produce organic acids or other compounds capable of contributing to mineral alteration.
• The extent of damage depends on climate, stone type, pore structure, surface condition and the organisms involved.
• Therefore Option A provides the most complete engineering interpretation.
• Roots growing into joints or cracks may exert mechanical pressure and enlarge existing discontinuities.
• Some organisms also produce organic acids or other compounds capable of contributing to mineral alteration.
• The extent of damage depends on climate, stone type, pore structure, surface condition and the organisms involved.
• Therefore Option A provides the most complete engineering interpretation.
వివరణ:
Question 9
ప్రశ్న 9
A masonry wall has no major rain penetration through its face, yet salts repeatedly appear near its lower portion. Which mechanism should be investigated first?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Porous masonry materials can draw water through small interconnected pores by capillary action.
• If the rising moisture contains dissolved salts, those salts are transported upward with the water.
• Evaporation near exposed surfaces can then concentrate and crystallize the salts, producing recurring deposits or internal crystallization damage.
• Investigation should therefore consider ground moisture, damp-proofing, drainage and sources of soluble salts rather than only direct rainfall.
• Option A correctly identifies the most relevant mechanism.
• If the rising moisture contains dissolved salts, those salts are transported upward with the water.
• Evaporation near exposed surfaces can then concentrate and crystallize the salts, producing recurring deposits or internal crystallization damage.
• Investigation should therefore consider ground moisture, damp-proofing, drainage and sources of soluble salts rather than only direct rainfall.
• Option A correctly identifies the most relevant mechanism.
వివరణ:
Question 10
ప్రశ్న 10
Match the deterioration mechanism with its most appropriate description:
1. Thermal weathering
2. Salt crystallization
3. Carbonate dissolution
4. Oxidation
P. Chemical reaction of carbonate stone with acidic moisture
Q. Repeated mineral expansion and contraction due to temperature change
R. Alteration of susceptible iron-bearing minerals in the presence of oxygen and moisture
S. Growth of crystals in pores after evaporation of salt-bearing water
1. Thermal weathering
2. Salt crystallization
3. Carbonate dissolution
4. Oxidation
P. Chemical reaction of carbonate stone with acidic moisture
Q. Repeated mineral expansion and contraction due to temperature change
R. Alteration of susceptible iron-bearing minerals in the presence of oxygen and moisture
S. Growth of crystals in pores after evaporation of salt-bearing water
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Thermal weathering is associated with repeated temperature-induced expansion and contraction, giving 1-Q.
• Salt crystallization occurs when dissolved salts precipitate and grow within or near the pore system, giving 2-S.
• Acidic moisture can chemically react with and dissolve carbonate minerals such as calcite, giving 3-P.
• Oxidation alters susceptible iron-bearing minerals in the presence of oxygen and moisture, giving 4-R.
• The complete correct matching is therefore 1-Q, 2-S, 3-P and 4-R, corresponding to Option A.
• Salt crystallization occurs when dissolved salts precipitate and grow within or near the pore system, giving 2-S.
• Acidic moisture can chemically react with and dissolve carbonate minerals such as calcite, giving 3-P.
• Oxidation alters susceptible iron-bearing minerals in the presence of oxygen and moisture, giving 4-R.
• The complete correct matching is therefore 1-Q, 2-S, 3-P and 4-R, corresponding to Option A.
వివరణ:
Question 11
ప్రశ్న 11
Stone is required for cladding at a coastal site exposed to salt-laden moisture and repeated wetting and drying. Which selection strategy is most appropriate?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Coastal exposure combines moisture, dissolved salts, repeated wetting and drying and often wind-driven rain.
• A highly connected pore system can facilitate entry and transport of salt-bearing water into the stone.
• Stable mineralogy, low detrimental moisture uptake and freedom from harmful cracks or weak veins therefore improve the prospects for durable service.
• Laboratory test data and experience with comparable exposure are more informative than appearance or geological name alone.
• Consequently Option A represents the appropriate engineering selection strategy.
• A highly connected pore system can facilitate entry and transport of salt-bearing water into the stone.
• Stable mineralogy, low detrimental moisture uptake and freedom from harmful cracks or weak veins therefore improve the prospects for durable service.
• Laboratory test data and experience with comparable exposure are more informative than appearance or geological name alone.
• Consequently Option A represents the appropriate engineering selection strategy.
వివరణ:
Question 12
ప్రశ్న 12
Two stones have similar compressive strength. Stone X has low water absorption and few connected pores, while Stone Y has high absorption and a strongly connected pore network. Which statement is most defensible for severe moisture exposure?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Compressive strength measures one mechanical property and does not fully characterize long-term environmental performance.
• Connected pores provide pathways for moisture and dissolved salts to penetrate and move through stone.
• Lower accessible absorption can therefore be advantageous under severe moisture exposure when other relevant properties are comparable.
• Mineral composition, cracks, pore-size distribution, salts and actual climatic conditions must still be considered before final selection.
• Hence Option A gives the appropriately qualified engineering conclusion.
• Connected pores provide pathways for moisture and dissolved salts to penetrate and move through stone.
• Lower accessible absorption can therefore be advantageous under severe moisture exposure when other relevant properties are comparable.
• Mineral composition, cracks, pore-size distribution, salts and actual climatic conditions must still be considered before final selection.
• Hence Option A gives the appropriately qualified engineering conclusion.
వివరణ:
Question 13
ప్రశ్న 13
In a durability test, a cleaned stone specimen has an initial dry mass of 500 g and a final dry mass of 487.5 g after the specified deterioration cycles. If percentage mass loss is calculated as [(initial mass − final mass) / initial mass] × 100, what is the value?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• The loss in mass is 500 − 487.5 = 12.5 g.
• Percentage mass loss is therefore (12.5 / 500) × 100.
• The ratio 12.5 / 500 equals 0.025.
• Multiplication by 100 gives a mass loss of 2.50 percent.
• Therefore Option B is correct; interpretation of whether that result is acceptable must be made against the applicable product or project requirement rather than an invented universal limit.
• Percentage mass loss is therefore (12.5 / 500) × 100.
• The ratio 12.5 / 500 equals 0.025.
• Multiplication by 100 gives a mass loss of 2.50 percent.
• Therefore Option B is correct; interpretation of whether that result is acceptable must be made against the applicable product or project requirement rather than an invented universal limit.
వివరణ:
Question 14
ప్రశ్న 14
Which statement best describes the principle of the durability test for natural building stones under IS 1126:2013?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• IS 1126:2013 is the Indian Standard method for determining durability or soundness of natural building stones.
• Its procedure subjects prepared specimens to repeated exposure involving sodium sulphate and drying so that damaging crystallization stresses can be developed in susceptible material.
• The specimens are observed for deterioration such as cracking or spalling and changes in mass are evaluated through the prescribed procedure.
• This accelerated laboratory test is different from a simple strength, colour or density determination.
• Therefore Option A correctly describes the basic test principle.
• Its procedure subjects prepared specimens to repeated exposure involving sodium sulphate and drying so that damaging crystallization stresses can be developed in susceptible material.
• The specimens are observed for deterioration such as cracking or spalling and changes in mass are evaluated through the prescribed procedure.
• This accelerated laboratory test is different from a simple strength, colour or density determination.
• Therefore Option A correctly describes the basic test principle.
వివరణ:
Question 15
ప్రశ్న 15
Match the natural-stone quality assessment with the applicable Indian Standard:
1. Weathering
2. Durability
3. Water transmission by capillary action
4. Surface softening by exposure to acidic atmospheres
P. IS 4122:1967
Q. IS 1125:2013
R. IS 1126:2013
S. IS 4121:1967
1. Weathering
2. Durability
3. Water transmission by capillary action
4. Surface softening by exposure to acidic atmospheres
P. IS 4122:1967
Q. IS 1125:2013
R. IS 1126:2013
S. IS 4121:1967
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• IS 1125:2013 specifies the method for determination of weathering of natural building stones, so 1-Q is correct.
• IS 1126:2013 covers determination of durability of natural building stones, giving 2-R.
• IS 4121:1967 deals specifically with water transmission rate by capillary action through natural building stones, giving 3-S.
• IS 4122:1967 addresses surface softening of natural building stones by exposure to acidic atmospheres, giving 4-P.
• Therefore the complete correct matching is 1-Q, 2-R, 3-S and 4-P, corresponding to Option A.
• IS 1126:2013 covers determination of durability of natural building stones, giving 2-R.
• IS 4121:1967 deals specifically with water transmission rate by capillary action through natural building stones, giving 3-S.
• IS 4122:1967 addresses surface softening of natural building stones by exposure to acidic atmospheres, giving 4-P.
• Therefore the complete correct matching is 1-Q, 2-R, 3-S and 4-P, corresponding to Option A.
వివరణ:
Question 16
ప్రశ్న 16
Which statement best characterizes the weathering test covered by IS 1125:2013?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• IS 1125:2013 is specifically a method for determining weathering behaviour of natural building stones.
• The procedure uses controlled laboratory conditioning and repeated exposure cycles rather than relying solely on casual visual inspection.
• Its purpose is to reveal changes associated with susceptibility to weathering under standardized accelerated conditions.
• It is separate from strength testing, chemical analysis and the durability method specified in IS 1126.
• Therefore Option A correctly identifies the nature of the weathering test without implying that it predicts an exact number of years of field service.
• The procedure uses controlled laboratory conditioning and repeated exposure cycles rather than relying solely on casual visual inspection.
• Its purpose is to reveal changes associated with susceptibility to weathering under standardized accelerated conditions.
• It is separate from strength testing, chemical analysis and the durability method specified in IS 1126.
• Therefore Option A correctly identifies the nature of the weathering test without implying that it predicts an exact number of years of field service.
వివరణ:
Question 17
ప్రశ్న 17
Which statement correctly distinguishes IS 1125:2013 from IS 1126:2013?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Both standards concern performance of natural building stone under deterioration-related laboratory assessment, but their prescribed methods are not identical.
• IS 1125:2013 is titled Determination of Weathering of Natural Building Stones — Method of Test.
• IS 1126:2013 is titled Determination of Durability of Natural Building Stones — Method of Test.
• Engineers should therefore refer to the test specifically required by the applicable stone specification or project requirement rather than treating the standards as interchangeable.
• Option A accurately preserves this distinction.
• IS 1125:2013 is titled Determination of Weathering of Natural Building Stones — Method of Test.
• IS 1126:2013 is titled Determination of Durability of Natural Building Stones — Method of Test.
• Engineers should therefore refer to the test specifically required by the applicable stone specification or project requirement rather than treating the standards as interchangeable.
• Option A accurately preserves this distinction.
వివరణ:
Question 18
ప్రశ్న 18
A stone block has excellent laboratory compressive strength but contains a continuous weathered seam passing through the block. What is the most appropriate quality decision for a heavily loaded exterior masonry unit?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Natural stone performance depends on the condition of the actual block as well as on average properties of intact material from the quarry.
• A continuous weathered seam may represent a zone of substantially reduced strength and cohesion.
• It can also provide an easy pathway for water entry and progressive environmental deterioration.
• A high compressive-strength value obtained from sound specimens therefore does not justify ignoring a major discontinuity in a structural block.
• Hence Option A is the appropriate quality-control judgement.
• A continuous weathered seam may represent a zone of substantially reduced strength and cohesion.
• It can also provide an easy pathway for water entry and progressive environmental deterioration.
• A high compressive-strength value obtained from sound specimens therefore does not justify ignoring a major discontinuity in a structural block.
• Hence Option A is the appropriate quality-control judgement.
వివరణ:
Question 19
ప్రశ్న 19
Why can the orientation of bedding or foliation influence weathering performance of stone masonry?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Bedding and foliation can introduce anisotropy into natural stone because properties may differ parallel and perpendicular to the planes.
• Weak or open planar features can provide preferential paths for moisture penetration and salt transport.
• Repeated environmental or mechanical stresses may also encourage splitting or delamination along these planes.
• Their orientation relative to rainfall, exposed surfaces, fixings and structural loads can therefore affect service performance.
• Option A correctly explains why fabric orientation is a durability consideration.
• Weak or open planar features can provide preferential paths for moisture penetration and salt transport.
• Repeated environmental or mechanical stresses may also encourage splitting or delamination along these planes.
• Their orientation relative to rainfall, exposed surfaces, fixings and structural loads can therefore affect service performance.
• Option A correctly explains why fabric orientation is a durability consideration.
వివరణ:
Question 20
ప్రశ్న 20
Polished calcitic marble is proposed for an exterior facade immediately adjacent to a process that regularly releases acidic condensate. Which assessment is most appropriate?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Marble is a metamorphic stone, but many common marbles consist predominantly of carbonate minerals such as calcite.
• Acidic condensate can chemically react with those carbonate minerals and cause gradual surface recession or loss of polish.
• A polished surface improves appearance but does not fundamentally change the chemical susceptibility of the mineral itself.
• Selection for an aggressive industrial exposure should therefore consider chemical compatibility, test evidence and any protective system proposed.
• Hence Option A is the appropriate engineering response.
• Acidic condensate can chemically react with those carbonate minerals and cause gradual surface recession or loss of polish.
• A polished surface improves appearance but does not fundamentally change the chemical susceptibility of the mineral itself.
• Selection for an aggressive industrial exposure should therefore consider chemical compatibility, test evidence and any protective system proposed.
• Hence Option A is the appropriate engineering response.
వివరణ:
Question 21
ప్రశ్న 21
A sandstone contains abundant swelling clay within its cement and pores. Why may repeated wetting and drying be particularly harmful?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Some clay minerals undergo substantial moisture-related dimensional changes compared with relatively stable quartz grains.
• Repeated wetting can cause swelling, while drying can be accompanied by contraction.
• These repeated movements may weaken the cementing matrix or interfaces between grains and contribute to microcracking.
• Progressive damage can appear as scaling, flaking or granular disintegration in susceptible sandstone.
• Therefore Option A correctly links mineralogical composition with wet-dry durability.
• Repeated wetting can cause swelling, while drying can be accompanied by contraction.
• These repeated movements may weaken the cementing matrix or interfaces between grains and contribute to microcracking.
• Progressive damage can appear as scaling, flaking or granular disintegration in susceptible sandstone.
• Therefore Option A correctly links mineralogical composition with wet-dry durability.
వివరణ:
Question 22
ప్రశ్న 22
Which statement correctly distinguishes surface efflorescence from damaging salt crystallization within a stone?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Efflorescence commonly refers to visible salts deposited at an exposed surface after salt-bearing water evaporates.
• Such deposits can be aesthetically objectionable but need not always cause major structural damage to the stone itself.
• When crystallization occurs within pores beneath the surface, growing crystals can exert pressure against the pore walls.
• Repeated internal crystallization can therefore produce powdering, scaling and spalling even when the surface deposit is not visually dramatic.
• Option A correctly distinguishes appearance-related deposition from potentially disruptive internal salt action.
• Such deposits can be aesthetically objectionable but need not always cause major structural damage to the stone itself.
• When crystallization occurs within pores beneath the surface, growing crystals can exert pressure against the pore walls.
• Repeated internal crystallization can therefore produce powdering, scaling and spalling even when the surface deposit is not visually dramatic.
• Option A correctly distinguishes appearance-related deposition from potentially disruptive internal salt action.
వివరణ:
Question 23
ప్రశ్న 23
Consider the following statements about deterioration of building stones:
1. Salt crystallization is primarily a physical deterioration mechanism even though transport of the salts occurs in solution.
2. Acid attack on carbonate stone is primarily chemical deterioration.
3. High dry compressive strength alone guarantees durability in every environment.
4. Connected porosity can facilitate moisture and salt transport.
Which statements are correct?
1. Salt crystallization is primarily a physical deterioration mechanism even though transport of the salts occurs in solution.
2. Acid attack on carbonate stone is primarily chemical deterioration.
3. High dry compressive strength alone guarantees durability in every environment.
4. Connected porosity can facilitate moisture and salt transport.
Which statements are correct?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Statement 1 is correct because the principal disruptive action of salt crystallization is the mechanical stress generated within the pore system.
• Statement 2 is correct because acidic solutions react chemically with carbonate minerals such as calcite.
• Statement 3 is incorrect because durability also depends on mineralogy, moisture, pore structure, defects, salts and the environmental exposure.
• Statement 4 is correct because interconnected pores provide pathways for liquid water and dissolved salts.
• Therefore Statements 1, 2 and 4 are correct, making Option B the unique answer.
• Statement 2 is correct because acidic solutions react chemically with carbonate minerals such as calcite.
• Statement 3 is incorrect because durability also depends on mineralogy, moisture, pore structure, defects, salts and the environmental exposure.
• Statement 4 is correct because interconnected pores provide pathways for liquid water and dissolved salts.
• Therefore Statements 1, 2 and 4 are correct, making Option B the unique answer.
వివరణ:
Question 24
ప్రశ్న 24
Four stone lots are being compared for exposed coastal cladding. Based only on the stated information, which lot is the most promising candidate for further approval testing?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Coastal cladding is exposed to salt-bearing moisture, repeated wetting and drying and environmental temperature changes.
• Lot A combines favourable moisture behaviour, soundness, stable mineralogy and the best stated performance in exposure-related testing.
• Lot B's high compressive strength does not compensate automatically for open microcracks and high capillary uptake that can promote salt entry.
• Lot C shows direct evidence of poor salt-weathering behaviour, while Lot D contains a major continuous structural discontinuity despite its low absorption.
• Therefore Lot A is the most promising candidate based on the supplied data, although final acceptance would still require compliance with all applicable product and project requirements.
• Lot A combines favourable moisture behaviour, soundness, stable mineralogy and the best stated performance in exposure-related testing.
• Lot B's high compressive strength does not compensate automatically for open microcracks and high capillary uptake that can promote salt entry.
• Lot C shows direct evidence of poor salt-weathering behaviour, while Lot D contains a major continuous structural discontinuity despite its low absorption.
• Therefore Lot A is the most promising candidate based on the supplied data, although final acceptance would still require compliance with all applicable product and project requirements.
వివరణ:
Question 25
ప్రశ్న 25
An engineer is evaluating a stone for a facade subjected to wind-driven rain, capillary moisture from joints and periodic atmospheric pollution. Which approach provides the most reliable quality assessment?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Real facade exposure involves several interacting mechanisms rather than one isolated material property.
• Wind-driven rain and capillary transport control how moisture and contaminants enter the stone, while pore characteristics influence their movement and retention.
• Mineral stability and defects determine whether chemical alteration, salt crystallization or cracking is likely to become significant.
• Strength data are useful but must be interpreted together with durability-related test evidence and inspection of the actual quarry material.
• Therefore Option A gives the comprehensive engineering approach required for reliable quality assessment.
• Wind-driven rain and capillary transport control how moisture and contaminants enter the stone, while pore characteristics influence their movement and retention.
• Mineral stability and defects determine whether chemical alteration, salt crystallization or cracking is likely to become significant.
• Strength data are useful but must be interpreted together with durability-related test evidence and inspection of the actual quarry material.
• Therefore Option A gives the comprehensive engineering approach required for reliable quality assessment.
వివరణ:
Answer Key సమాధానాల పట్టిక
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Question 1 ప్రశ్న 1Answer: A. Ability to retain satisfactory engineering performance under the deteriorating influences expected during service సమాధానం: A.
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Question 2 ప్రశ్న 2Answer: A. Repeated differential thermal expansion and contraction producing microcracking సమాధానం: A.
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Question 3 ప్రశ్న 3Answer: A. Repeated freezing of pore water can generate disruptive stresses and progressively enlarge cracks. సమాధానం: A.
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Question 4 ప్రశ్న 4Answer: A. Crystal growth and related pressures can stress pore walls and cause granular disintegration, scaling or spalling. సమాధానం: A.
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Question 5 ప్రశ్న 5Answer: A. Moisture cycles can promote salt movement, mineral swelling or shrinkage and repeated dimensional stresses within susceptible stone. సమాధానం: A.
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Question 6 ప్రశ్న 6Answer: A. Chemical dissolution or reaction of carbonate minerals, leading to progressive surface loss సమాధానం: A.
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Question 7 ప్రశ్న 7Answer: A. Oxidation may produce staining and can contribute to local expansion or deterioration. సమాధానం: A.
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Question 8 ప్రశ్న 8Answer: A. They can retain moisture, exert local physical action and in some cases promote chemical alteration at the surface. సమాధానం: A.
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Question 9 ప్రశ్న 9Answer: A. Capillary rise of salt-bearing moisture from the ground or adjoining porous materials సమాధానం: A.
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Question 10 ప్రశ్న 10Answer: A. 1-Q, 2-S, 3-P, 4-R సమాధానం: A.
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Question 11 ప్రశ్న 11Answer: A. Prefer sound stone with favourable moisture behaviour, stable mineralogy and demonstrated resistance to the relevant salt and weather exposure. సమాధానం: A.
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Question 12 ప్రశ్న 12Answer: A. Stone X is generally the more promising candidate, although complete durability assessment requires additional properties and exposure-specific evaluation. సమాధానం: A.
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Question 13 ప్రశ్న 13Answer: B. 2.50 percent సమాధానం: B.
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Question 14 ప్రశ్న 14Answer: A. Specimens undergo repeated sodium-sulphate crystallization exposure, with deterioration assessed through changes such as mass loss, cracking or spalling. సమాధానం: A.
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Question 15 ప్రశ్న 15Answer: A. 1-Q, 2-R, 3-S, 4-P సమాధానం: A.
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Question 16 ప్రశ్న 16Answer: A. It uses a prescribed accelerated laboratory exposure involving repeated treatment cycles to evaluate susceptibility of natural building stone to weathering. సమాధానం: A.
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Question 17 ప్రశ్న 17Answer: A. IS 1125 deals with weathering assessment, whereas IS 1126 deals with durability or soundness testing; they are related but distinct standardized procedures. సమాధానం: A.
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Question 18 ప్రశ్న 18Answer: A. Reject or remove the defective portion because the weathered seam may govern failure and moisture deterioration. సమాధానం: A.
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Question 19 ప్రశ్న 19Answer: A. Planar weaknesses may provide preferential routes for water entry, splitting or delamination depending on their orientation to exposure and stress. సమాధానం: A.
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Question 20 ప్రశ్న 20Answer: A. Reconsider the material or provide a suitably justified protection strategy because acidic exposure can attack carbonate marble despite its polished finish. సమాధానం: A.
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Question 21 ప్రశ్న 21Answer: A. Moisture-related swelling and shrinkage can weaken grain bonding and promote scaling or granular disintegration. సమాధానం: A.
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Question 22 ప్రశ్న 22Answer: A. A visible surface deposit may be mainly cosmetic, whereas crystallization within pores beneath the surface can generate stresses capable of disrupting the stone fabric. సమాధానం: A.
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Question 23 ప్రశ్న 23Answer: B. 1, 2 and 4 only సమాధానం: B.
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Question 24 ప్రశ్న 24Answer: A. Lot A: sound structure, low accessible absorption, no harmful veins, stable mineralogy and the least deterioration during relevant salt-weathering tests సమాధానం: A.
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Question 25 ప్రశ్న 25Answer: A. Evaluate relevant strength, absorption and pore characteristics, capillary behaviour, weathering or durability response, mineral stability and actual defects together. సమాధానం: A.