Construction Materials Quiz: Aggregates
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Questions and Answers

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

    Name one mineral that can be found in aggregates.

    Silica

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

    <p>air voids</p> Signup and view all the answers

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

    <p>Super aggregates</p> Signup and view all the answers

    Match the types of aggregates with their characteristics:

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

    Aggregates are primarily used for their aesthetic value in concrete.

    <p>False</p> Signup and view all the answers

    What is the size range for coarse aggregates?

    <p>4.75 mm to 37.5 mm</p> Signup and view all the answers

    What effect does grading of aggregates have on fresh concrete?

    <p>Affects workability</p> Signup and view all the answers

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

    <p>weathering</p> Signup and view all the answers

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

    <p>False</p> Signup and view all the answers

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

    <p>Elongated aggregates</p> Signup and view all the answers

    What is one problem associated with using recycled aggregates?

    <p>Cost of crushing</p> Signup and view all the answers

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

    <p>True</p> Signup and view all the answers

    Name one application of aggregates in construction.

    <p>Used as fillers in concrete and mortar</p> Signup and view all the answers

    Match the following aggregate types with their characteristics:

    <p>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</p> Signup and view all the answers

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

    <p>The proportions of fine and coarse aggregates</p> Signup and view all the answers

    A higher Fineness Modulus indicates finer aggregates.

    <p>False</p> Signup and view all the answers

    What are the two sieve analysis methods mentioned?

    <p>Manual sieving method and mechanical sieving method</p> Signup and view all the answers

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

    <p>Fineness</p> Signup and view all the answers

    Match the sieve analysis method with its description:

    <p>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</p> Signup and view all the answers

    What is the purpose of gradation control in aggregate mixing?

    <p>To ensure uniformity of concrete production</p> Signup and view all the answers

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

    <p>False</p> Signup and view all the answers

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

    <p>Lower FM improves workability</p> Signup and view all the answers

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

    <p>True</p> Signup and view all the answers

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

    <p>Fineness Modulus</p> Signup and view all the answers

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

    <p>medium</p> Signup and view all the answers

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

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

    Match the types of gradation with their descriptions:

    <p>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</p> Signup and view all the answers

    Which sieve number corresponds to a size of 2.36 mm?

    <p>No. 4</p> Signup and view all the answers

    The fineness of aggregates is determined only by their coarseness.

    <p>False</p> Signup and view all the answers

    How is the fineness modulus calculated?

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

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

    <p>Segregation of the mortar from coarse aggregates</p> Signup and view all the answers

    Increased void spaces in concrete lead to lower permeability.

    <p>False</p> Signup and view all the answers

    List two effects of void spaces between aggregates in concrete.

    <p>Reduced strength and higher permeability</p> Signup and view all the answers

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

    <p>cement paste</p> Signup and view all the answers

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

    <p>Increases the effective water-cement ratio</p> Signup and view all the answers

    Properly controlled moisture content in aggregates ensures inconsistent concrete quality.

    <p>False</p> Signup and view all the answers

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

    <p>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</p> Signup and view all the answers

    What is the consequence of low moisture content in aggregates?

    <p>it can absorb water from the mix.</p> Signup and view all the answers

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

    <p>Workability</p> Signup and view all the answers

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

    <p>Alkali Silica</p> Signup and view all the answers

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

    <p>True</p> Signup and view all the answers

    Match the terms related to moisture content and their effects:

    <p>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</p> Signup and view all the answers

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

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

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

    <p>Changes in moisture content</p> Signup and view all the answers

    Alkali Silica Reaction is beneficial for the durability of concrete.

    <p>False</p> Signup and view all the answers

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

    <p>It affects the accuracy of water added to the mix.</p> Signup and view all the answers

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