Aggregate and Cement Testing - Advanced Concepts
Q. What does the term 'slump' refer to in concrete testing?
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A.
The density of the concrete mix
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B.
The workability of the concrete
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C.
The curing time of the concrete
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D.
The compressive strength of the concrete
Solution
Slump is a measure of the workability of fresh concrete, indicating how easily it can be placed and compacted.
Correct Answer: B — The workability of the concrete
Q. What is the effect of using too much water in a concrete mix?
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A.
Increased strength
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B.
Decreased workability
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C.
Increased porosity
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D.
Improved durability
Solution
Excess water in a concrete mix leads to increased porosity, which can reduce the strength and durability of the concrete.
Correct Answer: C — Increased porosity
Q. What is the main purpose of using fly ash as a partial replacement for cement?
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A.
To increase the weight of concrete
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B.
To improve workability
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C.
To enhance durability and reduce permeability
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D.
To decrease the setting time
Solution
Fly ash is used as a partial replacement for cement to enhance durability and reduce permeability in concrete.
Correct Answer: C — To enhance durability and reduce permeability
Q. What is the main purpose of using fly ash as a supplementary cementitious material?
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A.
To increase the weight of concrete
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B.
To improve workability and durability
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C.
To reduce the cost of concrete
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D.
To enhance color
Solution
Fly ash improves the workability and durability of concrete while also reducing the heat of hydration.
Correct Answer: B — To improve workability and durability
Q. What is the primary characteristic of high-performance concrete?
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A.
Low cost
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B.
High workability
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C.
Enhanced durability and strength
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D.
Lightweight
Solution
High-performance concrete is characterized by its enhanced durability and strength, making it suitable for demanding applications.
Correct Answer: C — Enhanced durability and strength
Q. What is the primary function of admixtures in concrete?
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A.
To reduce the cost of materials
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B.
To enhance specific properties of concrete
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C.
To increase the weight of concrete
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D.
To replace cement in the mix
Solution
Admixtures are used to enhance specific properties of concrete, such as workability, setting time, and durability.
Correct Answer: B — To enhance specific properties of concrete
Q. What is the primary function of steel reinforcement in concrete?
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A.
To improve thermal insulation
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B.
To enhance tensile strength
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C.
To reduce weight
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D.
To increase workability
Solution
Steel reinforcement is added to concrete to enhance its tensile strength, as concrete is weak in tension.
Correct Answer: B — To enhance tensile strength
Q. What is the primary purpose of conducting a sieve analysis on aggregates?
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A.
To determine the moisture content
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B.
To assess the particle size distribution
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C.
To evaluate the compressive strength
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D.
To check for impurities
Solution
Sieve analysis is performed to determine the particle size distribution of aggregates, which is crucial for ensuring proper mix design in concrete.
Correct Answer: B — To assess the particle size distribution
Q. What is the primary purpose of conducting a slump test?
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A.
To measure the density of concrete
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B.
To assess the workability of concrete
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C.
To determine the compressive strength
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D.
To evaluate the curing process
Solution
The slump test is used to assess the workability of concrete, indicating how easily it can be mixed, placed, and finished.
Correct Answer: B — To assess the workability of concrete
Q. What is the significance of the water-cement ratio in concrete?
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A.
It affects the color of the concrete
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B.
It influences the workability and strength
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C.
It determines the curing time
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D.
It impacts the cost of materials
Solution
The water-cement ratio is critical as it directly influences the workability, strength, and durability of the concrete.
Correct Answer: B — It influences the workability and strength
Q. Which admixture is commonly used to accelerate the setting time of concrete?
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A.
Retarding admixture
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B.
Water-reducing admixture
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C.
Accelerating admixture
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D.
Air-entraining admixture
Solution
Accelerating admixtures are used to speed up the setting time of concrete, especially in cold weather conditions.
Correct Answer: C — Accelerating admixture
Q. Which test is commonly used to determine the fineness of cement?
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A.
Blaine air permeability test
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B.
Vicat needle test
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C.
Le Chatelier test
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D.
Slump test
Solution
The Blaine air permeability test measures the fineness of cement by determining the surface area of the particles.
Correct Answer: A — Blaine air permeability test
Q. Which test is used to determine the compressive strength of concrete?
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A.
Flexural test
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B.
Tensile test
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C.
Cube test
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D.
Impact test
Solution
The cube test is a standard method for determining the compressive strength of concrete by testing concrete cubes.
Correct Answer: C — Cube test
Q. Which type of aggregate is preferred for high-strength concrete?
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A.
Coarse aggregate
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B.
Fine aggregate
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C.
Recycled aggregate
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D.
Lightweight aggregate
Solution
Coarse aggregates are preferred for high-strength concrete as they provide better load-bearing capacity and structural integrity.
Correct Answer: A — Coarse aggregate
Q. Which type of brick is known for its high compressive strength and low water absorption?
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A.
Clay brick
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B.
Concrete brick
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C.
Fly ash brick
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D.
Sand-lime brick
Solution
Sand-lime bricks are known for their high compressive strength and low water absorption, making them suitable for various construction applications.
Correct Answer: D — Sand-lime brick
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