Please keep at least one language enabled. || కనీసం ఒక భాషను ఎంచుకోండి.
Question 1
ప్రశ్న 1
Match each brick-testing function with the applicable Indian Standard:
1. Determination of compressive strength
2. Determination of water absorption
3. Determination of efflorescence
4. Sampling of burnt clay bricks and burnt clay tiles
P. IS 3495 (Part 1):2019
Q. IS 3495 (Part 2):2019
R. IS 3495 (Part 3):2019
S. IS 5454:2024
1. Determination of compressive strength
2. Determination of water absorption
3. Determination of efflorescence
4. Sampling of burnt clay bricks and burnt clay tiles
P. IS 3495 (Part 1):2019
Q. IS 3495 (Part 2):2019
R. IS 3495 (Part 3):2019
S. IS 5454:2024
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• IS 3495 (Part 1):2019 specifies the method for determining compressive strength of burnt clay building bricks.
• IS 3495 (Part 2):2019 covers determination of water absorption, including the 24-hour immersion procedure and additional boiling-water provisions.
• IS 3495 (Part 3):2019 specifies the procedure for assessing efflorescence on burnt clay building bricks.
• IS 5454:2024 is the current standard dealing with methods of sampling for burnt clay bricks and burnt clay tiles.
• Therefore the correct matching is 1-P, 2-Q, 3-R and 4-S, making Option A correct.
• IS 3495 (Part 2):2019 covers determination of water absorption, including the 24-hour immersion procedure and additional boiling-water provisions.
• IS 3495 (Part 3):2019 specifies the procedure for assessing efflorescence on burnt clay building bricks.
• IS 5454:2024 is the current standard dealing with methods of sampling for burnt clay bricks and burnt clay tiles.
• Therefore the correct matching is 1-P, 2-Q, 3-R and 4-S, making Option A correct.
వివరణ:
Question 2
ప్రశ్న 2
A solid burnt clay brick fails under a maximum compressive load of 240 kN. If the average area of its two bed faces is 17,100 mm², what compressive strength should be reported to the nearest 0.1 N/mm²?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Compressive strength is calculated by dividing the maximum load at failure by the average loaded area of the bed faces.
• The failure load of 240 kN is equal to 240,000 N.
• Therefore the strength is 240,000 / 17,100 = approximately 14.035 N/mm².
• IS 3495 (Part 1):2019 requires the average compressive-strength result to be reported to the nearest 0.1 N/mm².
• The corresponding reported value is therefore 14.0 N/mm², so Option B is correct.
• The failure load of 240 kN is equal to 240,000 N.
• Therefore the strength is 240,000 / 17,100 = approximately 14.035 N/mm².
• IS 3495 (Part 1):2019 requires the average compressive-strength result to be reported to the nearest 0.1 N/mm².
• The corresponding reported value is therefore 14.0 N/mm², so Option B is correct.
వివరణ:
Question 3
ప్రశ్న 3
During the compressive-strength test of a prepared solid brick specimen under IS 3495 (Part 1):2019, which loading procedure is correct?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• The compressive-strength test requires controlled axial loading rather than impact or arbitrary loading.
• The specified loading rate is 7 ± 1 N/mm² per minute until the specimen fails.
• Controlling the loading rate improves consistency and comparability between different brick specimens and laboratories.
• The specimen must also be carefully centred between the testing-machine platens to avoid unintended eccentric loading.
• Therefore Option A accurately describes the specified loading procedure.
• The specified loading rate is 7 ± 1 N/mm² per minute until the specimen fails.
• Controlling the loading rate improves consistency and comparability between different brick specimens and laboratories.
• The specimen must also be carefully centred between the testing-machine platens to avoid unintended eccentric loading.
• Therefore Option A accurately describes the specified loading procedure.
వివరణ:
Question 4
ప్రశ్న 4
Which sequence most accurately represents the pre-conditioning of a solid burnt clay brick for compressive-strength testing under IS 3495 (Part 1):2019?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Solid brick specimens are first immersed in water at the prescribed temperature for 24 hours and surplus moisture is then drained.
• Unevenness of the bed faces is removed to provide smooth and parallel bearing surfaces for compression testing.
• The frog, where present, and relevant bed-face voids are filled or capped with suitable cement-sand mortar having adequate strength.
• The prepared specimens are kept under damp jute bags for 24 hours and subsequently immersed in clean water for three days before testing.
• Option B is therefore the only sequence consistent with the prescribed pre-conditioning procedure.
• Unevenness of the bed faces is removed to provide smooth and parallel bearing surfaces for compression testing.
• The frog, where present, and relevant bed-face voids are filled or capped with suitable cement-sand mortar having adequate strength.
• The prepared specimens are kept under damp jute bags for 24 hours and subsequently immersed in clean water for three days before testing.
• Option B is therefore the only sequence consistent with the prescribed pre-conditioning procedure.
వివరణ:
Question 5
ప్రశ్న 5
Which statement correctly distinguishes the compressive-strength preparation of perforated bricks from that of solid bricks under IS 3495 (Part 1):2019?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• IS 3495 (Part 1):2019 contains a separate procedure for perforated bricks because their geometry differs from that of solid bricks.
• The perforations are not filled with mortar during specimen preparation.
• The method also states that mortar capping is not provided for these perforated specimens.
• Their compressive strength is evaluated using the appropriate net loaded area rather than pretending that the perforations are solid material.
• Therefore Option B correctly identifies the important procedural distinction.
• The perforations are not filled with mortar during specimen preparation.
• The method also states that mortar capping is not provided for these perforated specimens.
• Their compressive strength is evaluated using the appropriate net loaded area rather than pretending that the perforations are solid material.
• Therefore Option B correctly identifies the important procedural distinction.
వివరణ:
Question 6
ప్రశ్న 6
For compressive-strength calculation, which denominator is correctly associated with the brick type under IS 3495 (Part 1):2019?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Compressive stress must be based on the area actually relevant to transmitting the compressive load.
• For a solid brick, the reported strength is obtained using the average area of the bed faces.
• For a perforated brick, the calculation uses the average net area of the two faces under compression because the perforations do not contribute solid bearing area.
• Using mass, perimeter or gross volume would be dimensionally and mechanically inappropriate for calculating compressive stress.
• Therefore Option B correctly distinguishes the area basis for the two procedures.
• For a solid brick, the reported strength is obtained using the average area of the bed faces.
• For a perforated brick, the calculation uses the average net area of the two faces under compression because the perforations do not contribute solid bearing area.
• Using mass, perimeter or gross volume would be dimensionally and mechanically inappropriate for calculating compressive stress.
• Therefore Option B correctly distinguishes the area basis for the two procedures.
వివరణ:
Question 7
ప్రశ్న 7
Before determining 24-hour water absorption under IS 3495 (Part 2):2019, how are brick specimens brought to the required dry condition?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• The dry reference mass is fundamental to the calculation of water absorption, so a standardized drying procedure is required.
• Specimens are dried in a ventilated oven at 105 to 115°C for not less than 24 hours.
• Drying continues until two successive weighings taken at two-hour intervals satisfy the specified constant-mass condition.
• The specimens are then cooled to room temperature before the dry mass is obtained, and specimens still warm to the touch are not used for that weighing.
• Therefore Option A correctly describes the required pre-conditioning.
• Specimens are dried in a ventilated oven at 105 to 115°C for not less than 24 hours.
• Drying continues until two successive weighings taken at two-hour intervals satisfy the specified constant-mass condition.
• The specimens are then cooled to room temperature before the dry mass is obtained, and specimens still warm to the touch are not used for that weighing.
• Therefore Option A correctly describes the required pre-conditioning.
వివరణ:
Question 8
ప్రశ్న 8
A brick has an oven-dry mass of 2.44 kg and a mass of 2.79 kg after the prescribed 24-hour immersion. What is its water absorption to the nearest 0.1 percent by mass?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Water absorption by mass is calculated as [(M2 − M1) / M1] × 100, where M1 is the dry mass and M2 is the mass after immersion.
• The gain in mass is 2.79 − 2.44 = 0.35 kg.
• Dividing the gain by the dry mass gives 0.35 / 2.44 = approximately 0.14344.
• Multiplication by 100 gives approximately 14.34 percent, which is reported to the nearest 0.1 percent as 14.3 percent.
• Therefore Option C is correct.
• The gain in mass is 2.79 − 2.44 = 0.35 kg.
• Dividing the gain by the dry mass gives 0.35 / 2.44 = approximately 0.14344.
• Multiplication by 100 gives approximately 14.34 percent, which is reported to the nearest 0.1 percent as 14.3 percent.
• Therefore Option C is correct.
వివరణ:
Question 9
ప్రశ్న 9
In the 24-hour water-absorption procedure of IS 3495 (Part 2):2019, which practice is correct after the immersed brick is removed from water?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• After the 24-hour immersion, superficial water adhering to the specimen must not be included as part of the absorbed-water mass.
• The brick is therefore removed and traces of surface water are wiped away using a damp cloth.
• The saturated mass must then be obtained promptly before appreciable moisture is lost from the brick.
• The specified procedure requires completion of weighing within three minutes after removal from the water.
• Consequently Option B correctly states the handling and weighing requirement.
• The brick is therefore removed and traces of surface water are wiped away using a damp cloth.
• The saturated mass must then be obtained promptly before appreciable moisture is lost from the brick.
• The specified procedure requires completion of weighing within three minutes after removal from the water.
• Consequently Option B correctly states the handling and weighing requirement.
వివరణ:
Question 10
ప్రశ్న 10
Which sequence correctly describes the 5-hour boiling-water absorption procedure included in IS 3495 (Part 2):2019?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• The boiling-water procedure begins with the specimen submerged in clean distilled water at a temperature between 15 and 30°C.
• The water is heated to boiling within one hour rather than placing the specimen abruptly into an uncontrolled boiling condition.
• Boiling is then continued for five hours so that a high degree of saturation can be achieved.
• The specimen is allowed to cool naturally with the water to between 15 and 30°C before surface water is wiped away and the mass is obtained.
• Therefore Option B accurately describes the prescribed sequence.
• The water is heated to boiling within one hour rather than placing the specimen abruptly into an uncontrolled boiling condition.
• Boiling is then continued for five hours so that a high degree of saturation can be achieved.
• The specimen is allowed to cool naturally with the water to between 15 and 30°C before surface water is wiped away and the mass is obtained.
• Therefore Option B accurately describes the prescribed sequence.
వివరణ:
Question 11
ప్రశ్న 11
For a brick, M1 = 2500 g is the oven-dry mass, M2 = 2840 g is the mass after 24-hour cold-water immersion, and M3 = 2940 g is the mass after the 5-hour boiling-water procedure. What is the saturation coefficient?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• The saturation coefficient is the ratio of the water absorbed during the 24-hour cold-water test to that absorbed during the 5-hour boiling-water test.
• The 24-hour mass gain is M2 − M1 = 2840 − 2500 = 340 g.
• The boiling-water mass gain is M3 − M1 = 2940 − 2500 = 440 g.
• Therefore the saturation coefficient is 340 / 440 = approximately 0.7727.
• Rounded suitably, the value is 0.773 and Option B is correct.
• The 24-hour mass gain is M2 − M1 = 2840 − 2500 = 340 g.
• The boiling-water mass gain is M3 − M1 = 2940 − 2500 = 440 g.
• Therefore the saturation coefficient is 340 / 440 = approximately 0.7727.
• Rounded suitably, the value is 0.773 and Option B is correct.
వివరణ:
Question 12
ప్రశ్న 12
Which sequence most accurately describes the efflorescence test under IS 3495 (Part 3):2019?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Before the efflorescence test, adhering dirt that could be mistaken for a salt deposit is removed by brushing.
• The end of the brick is placed in distilled water with the depth of immersion maintained at 25 mm.
• The arrangement is kept under the prescribed warm, well-ventilated conditions while the water is absorbed and surplus moisture evaporates.
• A similar quantity of water is then introduced and allowed to evaporate again before the final surface condition is assessed.
• Therefore Option A correctly describes the essential two-cycle efflorescence procedure.
• The end of the brick is placed in distilled water with the depth of immersion maintained at 25 mm.
• The arrangement is kept under the prescribed warm, well-ventilated conditions while the water is absorbed and surplus moisture evaporates.
• A similar quantity of water is then introduced and allowed to evaporate again before the final surface condition is assessed.
• Therefore Option A correctly describes the essential two-cycle efflorescence procedure.
వివరణ:
Question 13
ప్రశ్న 13
After the prescribed efflorescence procedure, a thin salt deposit covers approximately 8 percent of the exposed brick surface. How should the result be classified?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• A 'nil' rating applies only when there is no perceptible deposit of efflorescence.
• A 'slight' rating applies when not more than 10 percent of the exposed area is covered by a thin salt deposit.
• The stated coverage of approximately 8 percent lies within this slight category.
• Moderate efflorescence involves a heavier deposit extending beyond the slight condition and covering up to 50 percent without surface powdering or flaking.
• Therefore the correct classification is Slight and Option B is correct.
• A 'slight' rating applies when not more than 10 percent of the exposed area is covered by a thin salt deposit.
• The stated coverage of approximately 8 percent lies within this slight category.
• Moderate efflorescence involves a heavier deposit extending beyond the slight condition and covering up to 50 percent without surface powdering or flaking.
• Therefore the correct classification is Slight and Option B is correct.
వివరణ:
Question 14
ప్రశ్న 14
A brick develops a relatively heavy salt deposit covering about 45 percent of its exposed surface, but there is no powdering or flaking. What is the appropriate efflorescence rating?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• The deposit described is greater than the amount permitted under the slight category.
• Moderate efflorescence covers the condition where a heavier salt deposit extends over up to 50 percent of the exposed brick surface.
• For the moderate category, the surface remains free from the powdering or flaking associated with the most severe condition.
• Heavy efflorescence applies when a heavy salt deposit covers 50 percent or more of the exposed area without powdering or flaking.
• With approximately 45 percent coverage and no surface deterioration, the correct rating is Moderate, making Option B correct.
• Moderate efflorescence covers the condition where a heavier salt deposit extends over up to 50 percent of the exposed brick surface.
• For the moderate category, the surface remains free from the powdering or flaking associated with the most severe condition.
• Heavy efflorescence applies when a heavy salt deposit covers 50 percent or more of the exposed area without powdering or flaking.
• With approximately 45 percent coverage and no surface deterioration, the correct rating is Moderate, making Option B correct.
వివరణ:
Question 15
ప్రశ్న 15
A brick shows a heavy salt deposit accompanied by powdering and flaking of its exposed surface. How is the efflorescence rated under IS 3495 (Part 3):2019?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Efflorescence classification considers not only the area covered by salt deposits but also whether physical deterioration accompanies the deposit.
• A heavy deposit without powdering or flaking is classified as Heavy when the specified area criterion is met.
• Once a heavy deposit is accompanied by powdering and/or flaking of the exposed surface, the condition becomes more severe.
• IS 3495 (Part 3):2019 identifies this deterioration condition as Serious efflorescence.
• Therefore Option D is the correct rating.
• A heavy deposit without powdering or flaking is classified as Heavy when the specified area criterion is met.
• Once a heavy deposit is accompanied by powdering and/or flaking of the exposed surface, the condition becomes more severe.
• IS 3495 (Part 3):2019 identifies this deterioration condition as Serious efflorescence.
• Therefore Option D is the correct rating.
వివరణ:
Question 16
ప్రశ్న 16
Which practice correctly reflects the dimensional checking of common burnt clay bricks under the applicable product specification?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Dimensional conformity of common burnt clay bricks is assessed using grouped measurements rather than by cherry-picking one apparently regular unit.
• Whole bricks from the sample are arranged in contact with one another in a straight line on a level surface.
• The overall dimension is measured with a suitable steel tape or other sufficiently long inextensible measuring device.
• The grouped method evaluates cumulative dimensional variation that is important in masonry construction and mortar-joint control.
• Therefore Option B correctly describes the essential dimensional-checking procedure.
• Whole bricks from the sample are arranged in contact with one another in a straight line on a level surface.
• The overall dimension is measured with a suitable steel tape or other sufficiently long inextensible measuring device.
• The grouped method evaluates cumulative dimensional variation that is important in masonry construction and mortar-joint control.
• Therefore Option B correctly describes the essential dimensional-checking procedure.
వివరణ:
Question 17
ప్రశ్న 17
Twenty modular bricks of nominal product size 190 × 90 × 90 mm give combined measurements of 3878 mm in length, 1842 mm in width and 1770 mm in height. Using the grouped limits of 3800 ± 80 mm for length and 1800 ± 40 mm for both width and height, what is the correct conclusion?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• The acceptable combined length range is 3800 ± 80 mm, or 3720 mm to 3880 mm, so 3878 mm complies.
• The acceptable combined width range is 1800 ± 40 mm, or 1760 mm to 1840 mm.
• The measured width of 1842 mm exceeds the upper limit by 2 mm and therefore fails.
• The measured height of 1770 mm lies within the corresponding 1760 mm to 1840 mm permissible range.
• Hence only the width measurement fails and Option C is correct.
• The acceptable combined width range is 1800 ± 40 mm, or 1760 mm to 1840 mm.
• The measured width of 1842 mm exceeds the upper limit by 2 mm and therefore fails.
• The measured height of 1770 mm lies within the corresponding 1760 mm to 1840 mm permissible range.
• Hence only the width measurement fails and Option C is correct.
వివరణ:
Question 18
ప్రశ్న 18
Which statement best expresses the purpose of sampling under IS 5454:2024 before laboratory testing of a brick consignment?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• A conformity decision about a consignment must be based on specimens that fairly represent the lot being evaluated.
• Deliberately selecting unusually good or unusually poor bricks introduces sampling bias and can make the test results misleading.
• IS 5454:2024 provides the current sampling framework for burnt clay bricks and burnt clay tiles, including criteria relevant to conformity assessment.
• Representative sampling and standardized testing perform different functions and one does not replace the other.
• Therefore Option B correctly states the principal quality-control purpose of the sampling procedure.
• Deliberately selecting unusually good or unusually poor bricks introduces sampling bias and can make the test results misleading.
• IS 5454:2024 provides the current sampling framework for burnt clay bricks and burnt clay tiles, including criteria relevant to conformity assessment.
• Representative sampling and standardized testing perform different functions and one does not replace the other.
• Therefore Option B correctly states the principal quality-control purpose of the sampling procedure.
వివరణ:
Question 19
ప్రశ్న 19
Consider the following statements about brick testing:
1. IS 3495 specifies test methods for relevant brick properties.
2. The applicable product specification provides acceptance or performance requirements for the brick product.
3. A test-method standard by itself necessarily supplies the class limit for every type of brick product.
4. Sampling requirements should be considered separately from the mechanical or physical test procedure.
Which statements are correct?
1. IS 3495 specifies test methods for relevant brick properties.
2. The applicable product specification provides acceptance or performance requirements for the brick product.
3. A test-method standard by itself necessarily supplies the class limit for every type of brick product.
4. Sampling requirements should be considered separately from the mechanical or physical test procedure.
Which statements are correct?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Statement 1 is correct because the IS 3495 series prescribes standardized procedures for determining properties such as strength, absorption and efflorescence.
• Statement 2 is correct because the product standard, such as the applicable specification for the particular brick type, establishes the performance requirements against which results are assessed.
• Statement 3 is incorrect because a test-method document explains how to determine a property but does not necessarily establish the universal acceptance limit for every brick product.
• Statement 4 is correct because representative sampling is governed by a separate sampling framework and must precede valid conformity testing.
• Therefore Statements 1, 2 and 4 are correct, making Option B the unique answer.
• Statement 2 is correct because the product standard, such as the applicable specification for the particular brick type, establishes the performance requirements against which results are assessed.
• Statement 3 is incorrect because a test-method document explains how to determine a property but does not necessarily establish the universal acceptance limit for every brick product.
• Statement 4 is correct because representative sampling is governed by a separate sampling framework and must precede valid conformity testing.
• Therefore Statements 1, 2 and 4 are correct, making Option B the unique answer.
వివరణ:
Question 20
ప్రశ్న 20
Which of the following is correctly regarded as a field-quality indication rather than a standardized quantitative IS 3495 laboratory test?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• The ringing-sound check is a traditional field observation used as a quick qualitative indication of whether a brick appears sound and well fired.
• It does not produce a standardized numerical value and cannot establish a precise compressive-strength class.
• Compressive strength under Part 1 and water absorption under Part 2 are prescribed laboratory determinations with defined calculations and specimen procedures.
• Efflorescence under Part 3 is also a standardized assessment carried out under specified exposure conditions and rating criteria.
• Therefore Option C is the only field-quality indication among the listed alternatives.
• It does not produce a standardized numerical value and cannot establish a precise compressive-strength class.
• Compressive strength under Part 1 and water absorption under Part 2 are prescribed laboratory determinations with defined calculations and specimen procedures.
• Efflorescence under Part 3 is also a standardized assessment carried out under specified exposure conditions and rating criteria.
• Therefore Option C is the only field-quality indication among the listed alternatives.
వివరణ:
Question 21
ప్రశ్న 21
During a 24-hour water-absorption test, a technician removes a specimen from the drying oven and weighs it while it is still noticeably warm. Why is this procedure unacceptable?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• The oven-dry mass serves as the reference denominator for calculating water absorption, so it must be determined under controlled conditions.
• IS 3495 (Part 2):2019 requires the dried brick to be cooled to room temperature before its dry mass is recorded.
• The procedure specifically avoids using specimens that remain warm to the touch.
• Weighing under a different thermal and moisture condition would depart from the standardized method and could impair comparability of results.
• Therefore Option A correctly identifies both the procedural requirement and the reason the technician's action is unacceptable.
• IS 3495 (Part 2):2019 requires the dried brick to be cooled to room temperature before its dry mass is recorded.
• The procedure specifically avoids using specimens that remain warm to the touch.
• Weighing under a different thermal and moisture condition would depart from the standardized method and could impair comparability of results.
• Therefore Option A correctly identifies both the procedural requirement and the reason the technician's action is unacceptable.
వివరణ:
Question 22
ప్రశ్న 22
A technician calculates brick water absorption using [(M2 − M1) / M2] × 100, where M1 is the oven-dry mass and M2 is the mass after 24-hour immersion. What is wrong with this calculation?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Water absorption is expressed as the increase in mass caused by absorbed water relative to the original dry mass of the specimen.
• The mass gain is correctly represented by M2 − M1.
• That gain must be divided by M1, the oven-dry mass, before multiplication by 100.
• Using M2 as the denominator would systematically produce a smaller percentage and would not conform to the specified calculation.
• Therefore Option B correctly identifies the technician's error.
• The mass gain is correctly represented by M2 − M1.
• That gain must be divided by M1, the oven-dry mass, before multiplication by 100.
• Using M2 as the denominator would systematically produce a smaller percentage and would not conform to the specified calculation.
• Therefore Option B correctly identifies the technician's error.
వివరణ:
Question 23
ప్రశ్న 23
A Class 20 common burnt clay brick sample has individual compressive strengths of 21.5, 20.8, 22.0, 19.7 and 16.8 N/mm². Its average water absorption is 14.6 percent and its efflorescence rating is slight. Based on these stated results, what prevents acceptance as Class 20?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• The average compressive strength is (21.5 + 20.8 + 22.0 + 19.7 + 16.8) / 5 = 20.16 N/mm², so the average exceeds 20 N/mm².
• For Class 20, an individual result may not fall more than 15 percent below the class strength, giving a lower limit of 20 × 0.85 = 17.0 N/mm².
• The individual result of 16.8 N/mm² is below 17.0 N/mm² and therefore fails this strength criterion.
• The stated water absorption of 14.6 percent is below the 15 percent maximum applicable to classes above 12.5, and slight efflorescence is also within the applicable limit.
• Hence the individual compressive-strength result is the stated cause of non-compliance, making Option C correct.
• For Class 20, an individual result may not fall more than 15 percent below the class strength, giving a lower limit of 20 × 0.85 = 17.0 N/mm².
• The individual result of 16.8 N/mm² is below 17.0 N/mm² and therefore fails this strength criterion.
• The stated water absorption of 14.6 percent is below the 15 percent maximum applicable to classes above 12.5, and slight efflorescence is also within the applicable limit.
• Hence the individual compressive-strength result is the stated cause of non-compliance, making Option C correct.
వివరణ:
Question 24
ప్రశ్న 24
Which reporting statement is correct for tests performed under IS 3495 (Parts 1 and 2):2019?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• Compressive strength is fundamentally a stress and is therefore reported in N/mm² rather than simply as a load in kN.
• IS 3495 (Part 1):2019 specifies reporting the average compressive strength to the nearest 0.1 N/mm².
• IS 3495 (Part 2):2019 specifies reporting the average 24-hour water absorption to the nearest 0.1 percent.
• These reporting rules provide a consistent level of precision appropriate to the respective test methods.
• Therefore Option B correctly states the reporting precision for the two properties.
• IS 3495 (Part 1):2019 specifies reporting the average compressive strength to the nearest 0.1 N/mm².
• IS 3495 (Part 2):2019 specifies reporting the average 24-hour water absorption to the nearest 0.1 percent.
• These reporting rules provide a consistent level of precision appropriate to the respective test methods.
• Therefore Option B correctly states the reporting precision for the two properties.
వివరణ:
Question 25
ప్రశ్న 25
A compressive-strength specimen has visibly uneven bed faces and is placed off-centre between the testing-machine platens. What is the principal validity concern?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• A valid compression test is intended to apply axial load through properly prepared bearing surfaces.
• Uneven bed faces can create localized contact stresses instead of distributing load reasonably uniformly across the specimen.
• Off-centre positioning can introduce eccentric loading and bending effects in addition to the intended compression.
• These conditions may cause premature or unrepresentative failure and therefore compromise the interpretation of the measured strength.
• Option A correctly explains why smooth parallel faces and careful centring are important parts of the standardized test procedure.
• Uneven bed faces can create localized contact stresses instead of distributing load reasonably uniformly across the specimen.
• Off-centre positioning can introduce eccentric loading and bending effects in addition to the intended compression.
• These conditions may cause premature or unrepresentative failure and therefore compromise the interpretation of the measured strength.
• Option A correctly explains why smooth parallel faces and careful centring are important parts of the standardized test procedure.
వివరణ:
Question 26
ప్రశ్న 26
A quality-control engineer receives a test report stating only that five bricks 'passed the compression test', without specimen identities, failure loads, loaded areas or individual calculated strengths. What is the most appropriate technical criticism?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
• A technically useful test report should permit the result to be traced to identifiable specimens and the measurements from which the result was calculated.
• For compressive strength, the maximum failure load and relevant loaded area determine the strength of each specimen.
• Individual values are also important where the product specification imposes limits on individual results as well as on the average.
• A bare statement that specimens 'passed' prevents an independent check of arithmetic, units, specimen variability and the acceptance criterion applied.
• Therefore Option A correctly identifies the quality-control weakness in the report.
• For compressive strength, the maximum failure load and relevant loaded area determine the strength of each specimen.
• Individual values are also important where the product specification imposes limits on individual results as well as on the average.
• A bare statement that specimens 'passed' prevents an independent check of arithmetic, units, specimen variability and the acceptance criterion applied.
• Therefore Option A correctly identifies the quality-control weakness in the report.
వివరణ:
Answer Key సమాధానాల పట్టిక
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Question 1 ప్రశ్న 1Answer: A. 1-P, 2-Q, 3-R, 4-S సమాధానం: A.
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Question 2 ప్రశ్న 2Answer: B. 14.0 N/mm² సమాధానం: B.
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Question 3 ప్రశ్న 3Answer: A. Apply axial load uniformly at 7 ± 1 N/mm² per minute until failure. సమాధానం: A.
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Question 4 ప్రశ్న 4Answer: B. Immerse for 24 h, drain surplus moisture, prepare smooth parallel bed faces, fill the frog or bed-face voids with suitable cement-sand mortar where required, keep under damp jute for 24 h, and then immerse in clean water for 3 days. సమాధానం: B.
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Question 5 ప్రశ్న 5Answer: B. No mortar is filled in the perforations and no mortar capping is provided for the perforated-brick procedure. సమాధానం: B.
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Question 6 ప్రశ్న 6Answer: B. Solid brick — average area of the bed faces; perforated brick — average net area of the two faces under compression సమాధానం: B.
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Question 7 ప్రశ్న 7Answer: A. They are dried in a ventilated oven at 105 to 115°C for at least 24 h until successive weighings satisfy the specified constant-mass criterion, and are then cooled to room temperature. సమాధానం: A.
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Question 8 ప్రశ్న 8Answer: C. 14.3 percent సమాధానం: C.
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Question 9 ప్రశ్న 9Answer: B. Wipe traces of water with a damp cloth and complete weighing within 3 minutes of removal from water. సమాధానం: B.
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Question 10 ప్రశ్న 10Answer: B. Submerge the specimen in clean distilled water at 15 to 30°C, heat the water to boiling within one hour, boil continuously for 5 h, allow natural cooling to 15 to 30°C, wipe and weigh. సమాధానం: B.
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Question 11 ప్రశ్న 11Answer: B. 0.773 సమాధానం: B.
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Question 12 ప్రశ్న 12Answer: A. Brush away misleading dirt, place one end of the brick in distilled water to a depth of 25 mm, allow absorption and evaporation under the prescribed conditions, repeat with a similar quantity of water, and assess the deposit after the second evaporation. సమాధానం: A.
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Question 13 ప్రశ్న 13Answer: B. Slight సమాధానం: B.
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Question 14 ప్రశ్న 14Answer: B. Moderate సమాధానం: B.
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Question 15 ప్రశ్న 15Answer: D. Serious సమాధానం: D.
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Question 16 ప్రశ్న 16Answer: B. Arrange the prescribed group of whole bricks in contact in a straight line on a level surface and measure the combined dimensions with a suitable inextensible measure. సమాధానం: B.
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Question 17 ప్రశ్న 17Answer: C. Only the width fails. సమాధానం: C.
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Question 18 ప్రశ్న 18Answer: B. To obtain a representative sample from the lot so that conformity decisions are not based on deliberately favourable or unfavourable specimens సమాధానం: B.
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Question 19 ప్రశ్న 19Answer: B. 1, 2 and 4 only సమాధానం: B.
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Question 20 ప్రశ్న 20Answer: C. Listening for a clear ringing sound when two bricks are struck lightly together సమాధానం: C.
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Question 21 ప్రశ్న 21Answer: A. The prescribed dry mass is to be obtained after the specimen has cooled to room temperature, and a specimen warm to the touch should not be used for the weighing. సమాధానం: A.
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Question 22 ప్రశ్న 22Answer: B. The denominator should be the oven-dry mass M1, not the saturated mass M2. సమాధానం: B.
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Question 23 ప్రశ్న 23Answer: C. One individual compressive-strength result falls below the permitted Class 20 individual lower limit. సమాధానం: C.
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Question 24 ప్రశ్న 24Answer: B. Average compressive strength is reported to the nearest 0.1 N/mm², while average water absorption is reported to the nearest 0.1 percent. సమాధానం: B.
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Question 25 ప్రశ్న 25Answer: A. The specimen may experience non-uniform or eccentric stress distribution, so the recorded failure load may not represent the intended axial compressive strength. సమాధానం: A.
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Question 26 ప్రశ్న 26Answer: A. The report lacks sufficient traceable test information to independently verify the calculated strengths and their conformity. సమాధానం: A.