Construction Materials Quiz: Aggregates

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What is permeability a measure of in fluid mechanics?

The strength of a material
The ability of a porous material to allow fluids to pass through (correct)
The thermal conductivity of a material
The density of a material

Aggregates made from blast-furnace slag are considered natural aggregates.

False (B)

Name one mineral that can be found in aggregates.

Silica

The presence of __________ in aggregates can reduce costs and improve concrete properties.

air voids Signup and view all the answers

Which of the following is NOT a type of aggregate classification?

Super aggregates (B) Signup and view all the answers

Match the types of aggregates with their characteristics:

Synthetic Aggregates = Thermally processed materials Recycled Aggregates = Concrete from demolished buildings Heavyweight Aggregates = Iron-based for radiation shielding Lightweight Aggregates = Increase thermal insulation Signup and view all the answers

Aggregates are primarily used for their aesthetic value in concrete.

False (B) Signup and view all the answers

What is the size range for coarse aggregates?

4.75 mm to 37.5 mm Signup and view all the answers

What effect does grading of aggregates have on fresh concrete?

Affects workability (A) Signup and view all the answers

Natural sands and gravels are products of _____ and the action of wind or water.

weathering Signup and view all the answers

The type of origin of aggregates has no impact on their strength and durability.

False (B) Signup and view all the answers

Which shape classification describes particles whose longest length is more than 3 times their thickness?

Elongated aggregates (B) Signup and view all the answers

What is one problem associated with using recycled aggregates?

Cost of crushing Signup and view all the answers

Aggregates with a smooth texture can improve the workability of concrete.

True (A) Signup and view all the answers

Name one application of aggregates in construction.

Used as fillers in concrete and mortar Signup and view all the answers

Match the following aggregate types with their characteristics:

Fine aggregates = 0.075 mm to 4.75 mm Coarse aggregates = 4.75 mm to 37.5 mm Natural aggregates = Products of weathering Artificial aggregates = Produced by crushing natural stone Signup and view all the answers

What does the Fineness Modulus (FM) help determine in concrete mix design?

The proportions of fine and coarse aggregates (A) Signup and view all the answers

A higher Fineness Modulus indicates finer aggregates.

False (B) Signup and view all the answers

What are the two sieve analysis methods mentioned?

Manual sieving method and mechanical sieving method Signup and view all the answers

The __________ Modulus helps predict the amount of water required for the concrete mix.

Fineness Signup and view all the answers

Match the sieve analysis method with its description:

Manual sieving method = Involves hand sieving to determine particle sizes Mechanical sieving method = Uses machinery to perform the sieving process Dry sieving method = Conducted without the use of water Wet sieving method = Conducted using water for particle separation Signup and view all the answers

What is the purpose of gradation control in aggregate mixing?

To ensure uniformity of concrete production (C) Signup and view all the answers

A rich gradation refers to a sample of aggregate with a low proportion of small-sized particles.

False (B) Signup and view all the answers

Which statement accurately describes the relationship between Fineness Modulus and workability?

Lower FM improves workability (A) Signup and view all the answers

Sieve analysis determines particle size distribution using either mass or volume.

True (A) Signup and view all the answers

What is the empirical figure known as that determines the fineness of aggregates?

Fineness Modulus Signup and view all the answers

A gap gradation in aggregates refers to a sample with very little aggregate in the __________ size range.

medium Signup and view all the answers

What is the key benefit of using the Fineness Modulus in concrete mix designs?

It helps estimate the amount of aggregate needed for desired workability and strength. Signup and view all the answers

Match the types of gradation with their descriptions:

Dense gradation = Approximately equal amounts of various sizes Narrow gradation = Aggregate of approximately the same size Open gradation = Very little fine aggregate particles Gap gradation = Very little aggregate in the medium size range Signup and view all the answers

Which sieve number corresponds to a size of 2.36 mm?

No. 4 (D) Signup and view all the answers

The fineness of aggregates is determined only by their coarseness.

False (B) Signup and view all the answers

How is the fineness modulus calculated?

By adding the total percentage of weight retained on sieves and dividing by 100. Signup and view all the answers

What is one of the consequences of unsatisfactory gradation in concrete?

Segregation of the mortar from coarse aggregates (A) Signup and view all the answers

Increased void spaces in concrete lead to lower permeability.

False (B) Signup and view all the answers

List two effects of void spaces between aggregates in concrete.

Reduced strength and higher permeability Signup and view all the answers

Higher void content in concrete requires more ________ to fill the gaps.

cement paste Signup and view all the answers

What effect does excessive moisture in aggregates have on the concrete's water-cement ratio?

Increases the effective water-cement ratio (A) Signup and view all the answers

Properly controlled moisture content in aggregates ensures inconsistent concrete quality.

False (B) Signup and view all the answers

Match the following consequences of void spaces in concrete with their descriptions:

Reduced service life = Extended durability and longevity Higher permeability = Allows harmful substances to penetrate Increased material costs = Necessitates more cement paste Compromised workability = Less ease of mixing and placing Signup and view all the answers

What is the consequence of low moisture content in aggregates?

it can absorb water from the mix. Signup and view all the answers

Which property of concrete is affected by the moisture content of aggregates?

Workability (B) Signup and view all the answers

The ________ reaction occurs between alkaline cement paste and reactive silica in aggregates.

Alkali Silica Signup and view all the answers

Insufficient air entrainment can lead to high porosity of hardened concrete.

True (A) Signup and view all the answers

Match the terms related to moisture content and their effects:

High moisture content = Segregation and bleeding Low moisture content = Absorption of mix water Proper moisture control = Consistent concrete quality Volume changes = Cracking and structural issues Signup and view all the answers

Explain the relationship between void spaces and the durability of concrete.

Voids can act as weak points where cracks can initiate, reducing overall durability. Signup and view all the answers

Which of the following can lead to structural issues in concrete?

Changes in moisture content (B) Signup and view all the answers

Alkali Silica Reaction is beneficial for the durability of concrete.

False (B) Signup and view all the answers

How can the moisture content of aggregates affect the batching of concrete?

It affects the accuracy of water added to the mix. Signup and view all the answers

What are Aggregates?

Aggregates are inert materials used along with a binding material like cement or lime to produce mortar or concrete. They serve as fillers, reducing the cost of construction.

Types of Aggregates

Aggregates are categorized into fine aggregates (sand) and coarse aggregates (gravel, crushed stone).

Fine Aggregate

Fine aggregates are particles smaller than 4.75 mm (retained on No. 4 sieve) but larger than 0.075 mm (retained on No. 200 sieve).

Coarse Aggregate

Coarse aggregates are particles larger than 4.75 mm (retained on No. 4 sieve) and up to 37.5 mm (retained on No. 4 sieve).