Please keep at least one language enabled. || కనీసం ఒక భాషను ఎంచుకోండి.
Question 1
ప్రశ్న 1
Which statement most accurately describes workability of fresh concrete?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Workability is a broad fresh-concrete property rather than a single measure of fluidity. It concerns the effort required to mix, transport, place, consolidate and finish concrete satisfactorily. A workable mix should also remain sufficiently homogeneous during these operations. The required degree of workability depends on member geometry, reinforcement congestion, placing method and compaction equipment. Therefore Option A gives the most complete definition.
వివరణ:
Question 2
ప్రశ్న 2
Which statement best distinguishes consistency from the broader concept of workability?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Consistency describes how stiff, plastic or fluid a fresh concrete mixture is under specified conditions. It is therefore closely related to mobility and can be assessed using suitable consistency tests. Workability is a broader engineering concept because it also involves placement, compactability and maintenance of homogeneity. A very fluid concrete can still be unsatisfactory if it segregates severely. Therefore Option A correctly distinguishes the two concepts.
వివరణ:
Question 3
ప్రశ్న 3
In discussing fresh concrete, what does mobility most nearly represent?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Mobility concerns the ability of fresh concrete to move or flow under the available placing effort. It is particularly important in narrow sections, congested reinforcement and pumped concrete. Mobility contributes to workability but does not by itself define satisfactory fresh-concrete behaviour. A highly mobile mixture can still be unsuitable if it lacks cohesion and segregates. Therefore Option A is correct.
వివరణ:
Question 4
ప్రశ్న 4
Which description most accurately represents compactability of fresh concrete?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Freshly placed conventional concrete normally contains entrapped air that should be removed by suitable compaction. Compactability describes how readily the mixture can be brought to a dense condition with the available effort. Very stiff concrete generally requires greater compactive effort. A highly fluid concrete may be easy to compact but can still have poor overall workability if its stability is inadequate. Therefore Option A correctly describes compactability.
వివరణ:
Question 5
ప్రశ్న 5
What does cohesiveness of fresh concrete principally describe?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Cohesiveness concerns the internal stability of fresh concrete. A cohesive mixture keeps coarse aggregate, mortar and water sufficiently well distributed during transport and placement. Adequate mortar, fines and proper grading generally contribute to cohesion. Insufficient cohesion can lead to coarse-aggregate separation or excessive water migration. Therefore Option A correctly states the property.
వివరణ:
Question 6
ప్రశ్న 6
A concrete mix flows very easily but coarse aggregate rapidly settles while mortar rises to the top. How should this concrete be assessed?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Easy flow indicates high mobility or fluidity. However, satisfactory workability requires more than easy movement. The mixture should also retain adequate homogeneity during handling and placement. The observed separation of coarse aggregate and mortar is segregation and demonstrates inadequate stability. Therefore Option A is the correct assessment.
వివరణ:
Question 7
ప్రశ్న 7
If additional water is added to a concrete mix without changing any other constituent, which outcome is most likely?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Adding water normally makes fresh concrete more fluid and can increase slump. Beyond the properly proportioned amount, however, the additional water can reduce mixture stability. Excess water can promote bleeding and segregation and raises the effective water-cementitious-material ratio. This generally increases capillary porosity and reduces strength and durability after hardening. Therefore Option A is correct.
వివరణ:
Question 8
ప్రశ్న 8
For concrete mixtures having otherwise similar materials and proportions, how does rounded coarse aggregate generally affect workability compared with highly angular aggregate?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Rounded aggregate particles tend to move past one another more readily than angular particles. Their geometry generally causes lower internal friction in the fresh mixture. Consequently less paste or water may be required to obtain a given level of workability. Angular aggregate can provide beneficial interlock but commonly produces a harsher mixture. Therefore Option A is correct.
వివరణ:
Question 9
ప్రశ్న 9
For otherwise comparable concrete and the same required workability, increasing the nominal maximum aggregate size commonly tends to:
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Larger aggregate particles provide less total surface area per unit volume than smaller particles. Less surface therefore has to be coated and lubricated by cement paste. This commonly permits lower water and paste requirements for a specified workability. Maximum aggregate size must still be compatible with member dimensions, reinforcement spacing and placing conditions. Therefore Option A is correct.
వివరణ:
Question 10
ప్రశ్న 10
A concrete mix contains poorly graded aggregate with a shortage of intermediate particle sizes. Which fresh-concrete behaviour is most likely?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Suitable grading allows smaller aggregate particles to fill part of the void space between larger particles. A shortage of important intermediate sizes can create inefficient packing and greater void content. Additional paste may then be needed to fill the voids and lubricate the particle system. Poor grading can also produce a harsh or unstable concrete mixture. Therefore Option A is correct.
వివరణ:
Question 11
ప్రశ్న 11
A concrete mix contains too much coarse aggregate and insufficient mortar and fines. Which behaviour is most likely during placing?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Mortar and fine material fill spaces around coarse aggregate and provide lubrication during handling and placement. If their quantity is inadequate, coarse particles interfere strongly with one another. The concrete becomes harsh and difficult to place or compact around reinforcement and corners. Coarse aggregate may also separate from the insufficient mortar phase. Therefore Option A is correct.
వివరణ:
Question 12
ప్రశ్న 12
What is a likely fresh-concrete consequence of using an unnecessarily high fine-aggregate or very-fine-material content while keeping the other materials essentially unchanged?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Fine particles have a relatively large surface area that must be wetted and lubricated. Increasing the fine fraction can improve cohesiveness and resistance to segregation. Excessive fines, however, can make concrete sticky and increase water or paste demand for a given mobility. Good fresh-concrete behaviour therefore requires an appropriate balance of particle sizes. Hence Option A is correct.
వివరణ:
Question 13
ప్రశ్న 13
For a concrete mix that is harsh because the paste volume is inadequate, which modification most directly addresses the fresh-concrete deficiency without merely adding uncontrolled water?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Harshness often indicates inadequate lubrication of the aggregate skeleton. Simply adding water may increase fluidity temporarily but can damage stability and alter the designed water-cementitious-material ratio. Improving grading or providing sufficient paste can improve both mobility and cohesion. A suitable water-reducing admixture may also assist where appropriate. Therefore Option A is the sound engineering response.
వివరణ:
Question 14
ప్రశ్న 14
A water-reducing or superplasticizing admixture is correctly used in a concrete mix while the mixing-water content is kept unchanged. What is the expected primary fresh-concrete effect?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Water-reducing admixtures improve dispersion of cementitious particles in fresh concrete. At unchanged water content, this can increase fluidity and ease of placement. Alternatively, the water content can often be reduced while maintaining a specified workability. Dosage and compatibility must still be controlled because excessive or unsuitable admixture use can cause undesirable effects. Therefore Option A is correct.
వివరణ:
Question 15
ప్రశ్న 15
A concrete truck reaches the site after a substantial delay on a hot afternoon. No additional water has been added. Which fresh-concrete change is generally expected?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Fresh concrete normally loses consistency with elapsed time after mixing. Cement hydration progressively develops internal structure and consumes available water. Hot conditions can accelerate hydration and also increase evaporation. These effects commonly cause slump or other measures of consistency to decrease during delay. Therefore Option A is correct.
వివరణ:
Question 16
ప్రశ్న 16
Why is indiscriminate addition of water at the site an unsuitable response to slump loss during delayed concrete placement?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Additional water can temporarily make a stiffening mixture appear more workable. Unless the adjustment is specifically controlled and permitted, it alters the effective mixture proportions. A higher water-cementitious-material ratio generally reduces strength and increases permeability. Excess water can also reduce cohesion and increase bleeding or segregation. Therefore Option A is correct.
వివరణ:
Question 17
ప్రశ్న 17
What is segregation of fresh concrete?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Fresh concrete should remain reasonably homogeneous from mixing until final placement. Segregation occurs when its constituents separate and are no longer uniformly distributed. Common forms include coarse aggregate separating from the mortar or accumulation of paste-rich material in another region. Segregated concrete can produce honeycombing and non-uniform hardened properties. Therefore Option A is correct.
వివరణ:
Question 18
ప్రశ్న 18
Which construction practice is most likely to promote segregation of otherwise workable concrete?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Excessive free fall can cause the different concrete constituents to move and rebound differently. Coarse aggregate may separate from mortar during impact or subsequent flow. This reduces the homogeneity of the concrete placed in the form. Depositing concrete close to its final position reduces unnecessary movement and helps limit segregation. Therefore Option A is correct.
వివరణ:
Question 19
ప్రశ్న 19
Concrete in a wall form is subjected to excessive prolonged vibration after adequate compaction has already been achieved. What fresh-concrete defect may result?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Vibration is used to expel entrapped air and consolidate conventional concrete. Once adequate compaction has been achieved, unnecessarily prolonged vibration can destabilize a susceptible mixture. Coarse aggregate may settle while paste or water-rich material moves upward. The risk is greater in highly fluid or poorly cohesive concrete. Therefore Option A is correct.
వివరణ:
Question 20
ప్రశ్న 20
Which statement most accurately defines bleeding in fresh concrete?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Bleeding occurs while concrete is still plastic and the solid constituents undergo settlement. Some mixing water is displaced upward through the concrete. The water may reach the exposed surface or accumulate below aggregate particles or reinforcement. Bleeding is therefore commonly regarded as a form of segregation involving water. Hence Option A is correct.
వివరణ:
Question 21
ప్రశ్న 21
Excessive bleed water becomes trapped beneath a horizontal reinforcing bar. What is the most likely local consequence after hardening?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Bleed water may become trapped beneath horizontal reinforcement rather than reaching the exposed surface. When the water later disappears, the local zone can remain relatively porous and weak. This can reduce the quality of the concrete-steel interface. Poorer local bond may result compared with well-consolidated concrete having minimal bleeding. Therefore Option A is correct.
వివరణ:
Question 22
ప్రశ్న 22
A floor finisher begins final trowelling while a visible layer of bleed water still remains on the concrete surface. What problem is most likely?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Visible bleed water indicates that settlement and upward water movement are still occurring. Working this water back into the concrete surface locally increases the effective water-cementitious-material ratio. The resulting surface can become porous, weak or prone to dusting and laitance. Finishing operations should therefore be appropriately timed with respect to bleeding. Therefore Option A is correct.
వివరణ:
Question 23
ప్రశ్న 23
During hot, dry and windy weather, surface water evaporates from freshly placed concrete faster than bleeding can replace it. Which early-age problem becomes more likely?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Fresh concrete can lose moisture rapidly from an exposed surface in hot, dry and windy conditions. When evaporation exceeds the supply of bleed water, the surface begins to contract while the concrete remains plastic. Restraint to this contraction can generate shallow plastic shrinkage cracks. Evaporation control and prompt curing measures are therefore important. Hence Option A is correct.
వివరణ:
Question 24
ప్రశ్న 24
Concrete is to be pumped through a long pipeline and placed around congested reinforcement. Which combination of fresh-concrete properties is most desirable?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Pumped concrete must move through the pipeline without excessive resistance or blockage. It must also pass through congested reinforcement and fill the form effectively. Mobility alone is insufficient because an unstable mixture can segregate and cause blockage or non-uniform placement. Adequate cohesion, suitable grading and sufficient mortar are therefore needed together with mobility. Hence Option A is correct.
వివరణ:
Question 25
ప్రశ్న 25
Consider the following statements about fresh concrete:
1. High fluidity alone does not guarantee good workability if the concrete segregates.
2. Bleeding is associated with upward movement of water as solid particles settle.
3. Excessively angular aggregate generally increases internal friction and can reduce workability.
4. Excessive vibration can never cause segregation once concrete has entered the formwork.
Which statements are correct?
1. High fluidity alone does not guarantee good workability if the concrete segregates.
2. Bleeding is associated with upward movement of water as solid particles settle.
3. Excessively angular aggregate generally increases internal friction and can reduce workability.
4. Excessive vibration can never cause segregation once concrete has entered the formwork.
Which statements are correct?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Statement 1 is correct because workability includes stability and practical handling rather than fluidity alone. Statement 2 correctly describes the basic mechanism of bleeding. Statement 3 is correct because angular aggregate generally produces greater inter-particle friction than rounded aggregate. Statement 4 is incorrect because excessive vibration can promote segregation in a susceptible concrete mixture after adequate compaction has already been achieved. Therefore Statements 1, 2 and 3 are correct and Option B is the unique answer.
వివరణ:
Answer Key సమాధానాల పట్టిక
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Question 1 ప్రశ్న 1Answer: A. It is the overall ease with which concrete can be mixed, transported, placed, compacted and finished while maintaining satisfactory homogeneity. సమాధానం: A.
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Question 2 ప్రశ్న 2Answer: A. Consistency primarily indicates the relative fluidity or mobility of fresh concrete, whereas workability also includes ease of placement, compaction and resistance to loss of homogeneity. సమాధానం: A.
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Question 3 ప్రశ్న 3Answer: A. The ease with which the concrete can flow or move into the available space. సమాధానం: A.
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Question 4 ప్రశ్న 4Answer: A. The ease with which entrapped air can be expelled and the concrete brought to a dense condition using the available compaction effort. సమాధానం: A.
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Question 5 ప్రశ్న 5Answer: A. Its ability to keep the constituent materials uniformly distributed and resist segregation during handling and placement. సమాధానం: A.
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Question 6 ప్రశ్న 6Answer: A. It has high mobility but poor overall workability because its cohesion and stability are inadequate. సమాధానం: A.
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Question 7 ప్రశ్న 7Answer: A. Consistency and mobility may increase, but excessive water can increase bleeding and segregation and can reduce hardened strength and durability. సమాధానం: A.
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Question 8 ప్రశ్న 8Answer: A. Rounded aggregate generally improves workability because it produces lower inter-particle friction. సమాధానం: A.
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Question 9 ప్రశ్న 9Answer: A. Reduce the total aggregate surface area and therefore reduce water and paste demand, within practical structural limits. సమాధానం: A.
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Question 10 ప్రశ్న 10Answer: A. Inefficient packing, greater paste demand and an increased tendency toward harshness or segregation. సమాధానం: A.
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Question 11 ప్రశ్న 11Answer: A. The mix may become harsh, difficult to compact and prone to coarse-aggregate segregation. సమాధానం: A.
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Question 12 ప్రశ్న 12Answer: A. The mix may become sticky and cohesive but may require more water or paste to maintain the desired mobility. సమాధానం: A.
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Question 13 ప్రశ్న 13Answer: A. Improve the aggregate proportions or provide adequate paste volume while maintaining the required water-cementitious-material ratio. సమాధానం: A.
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Question 14 ప్రశ్న 14Answer: A. Workability or flow can increase without the same increase in water-cementitious-material ratio that would result from adding extra water. సమాధానం: A.
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Question 15 ప్రశ్న 15Answer: A. Loss of consistency and workability because hydration, evaporation and temperature effects continue during the delay. సమాధానం: A.
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Question 16 ప్రశ్న 16Answer: A. It may restore fluidity temporarily but can change the designed water-cementitious-material ratio, strength, durability and segregation resistance. సమాధానం: A.
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Question 17 ప్రశ్న 17Answer: A. Loss of homogeneity caused by separation of the constituent materials of the concrete mixture. సమాధానం: A.
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Question 18 ప్రశ్న 18Answer: A. Allowing concrete to fall freely from excessive height during placement. సమాధానం: A.
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Question 19 ప్రశ్న 19Answer: A. Segregation, with heavier aggregate tending to settle and paste or water moving upward. సమాధానం: A.
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Question 20 ప్రశ్న 20Answer: A. The upward movement of water toward the surface as the solid constituents tend to settle. సమాధానం: A.
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Question 21 ప్రశ్న 21Answer: A. A weakened paste zone and poorer bond beneath the reinforcement. సమాధానం: A.
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Question 22 ప్రశ్న 22Answer: A. The water may be worked into the surface, producing a weak, porous or laitance-rich top layer. సమాధానం: A.
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Question 23 ప్రశ్న 23Answer: A. Plastic shrinkage cracking సమాధానం: A.
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Question 24 ప్రశ్న 24Answer: A. Adequate mobility and compactability together with sufficient cohesion to resist segregation and blockage. సమాధానం: A.
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Question 25 ప్రశ్న 25Answer: B. 1, 2 and 3 only సమాధానం: B.