Chapter 10: Concrete Construction
84 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the purpose of adding admixtures to concrete?

  • To tailor concrete for specific functions (correct)
  • To reduce the compressive strength
  • To decrease the density
  • To increase the tensile strength

    • Which type of concrete has good insulating properties and is fundamentally noncombustible?

  • Gypsum concrete (correct)
  • High early-strength concrete
  • Water-permeable concrete
  • Ordinary stone concrete

    • What is the role of reinforcing steel in concrete?

  • To weaken the concrete structure
  • To increase the permeability of concrete
  • To reduce the density of concrete
  • To add compressive strength (correct)

    • Which method of prestressing concrete uses steel strands stretched between anchors?

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

    What is the ultimate compressive strength range of concrete in psi mentioned in the text?

    <p>$2500$ to $6000$ psi</p> Signup and view all the answers

    What is the significance of the depth of concrete cover around reinforcing bars?

    <p>It protects the bars from corrosion</p> Signup and view all the answers

    When prestressing concrete, what do the initial forces applied aim to achieve?

    <p>To place the concrete in compression</p> Signup and view all the answers

    In post-tensioned concrete, what danger is associated with cutting through reinforcing steel?

    <p>It weakens the post-tensioned element</p> Signup and view all the answers

    What does a superplasticizer do when used with concrete mix?

    <p>+Improves workability and pliability using less water</p> Signup and view all the answers

    Which property does concrete excel in?

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

    What is the main difference between pretensioned and post-tensioned reinforcement?

    <p>Pretensioned reinforcement involves steel strands that are tensioned before the concrete hardens.</p> Signup and view all the answers

    What is the purpose of covering reinforcing strands with grease or plastic tubing in post-tensioning?

    <p>To avoid binding of the strands with the concrete</p> Signup and view all the answers

    Why is precast concrete set in a controlled environment before being shipped to a construction site?

    <p>To ensure that it reaches its design strength before use</p> Signup and view all the answers

    What makes prestressed concrete systems more vulnerable to failure compared to ordinary reinforced concrete?

    <p>They may fail sooner due to the materials used and their design</p> Signup and view all the answers

    How can excessive vibration of concrete affect its quality?

    <p>It may cause water and cement to separate in the mix</p> Signup and view all the answers

    Why is the water-to-cement ratio considered the most important factor in determining concrete strength?

    <p>It influences the ultimate strength of the concrete</p> Signup and view all the answers

    What effect can using sand from an ocean beach have on concrete quality?

    <p>Introduces salt that can corrode reinforcing steel over time</p> Signup and view all the answers

    Why is good quality control important for concrete construction?

    <p>To ensure good strength and durability of structures</p> Signup and view all the answers

    What is done to reinforcing cables after they are anchored at one end during post-tensioning?

    <p>The cables are stretched using a jack at one end.</p> Signup and view all the answers

    What happens to precast concrete members after pouring and setting them according to specifications?

    <p>They are shipped to a construction site for immediate use.</p> Signup and view all the answers

    What is the primary cause of spalling in concrete?

    <p>The expansion of moisture within the concrete</p> Signup and view all the answers

    Which temperature range is ideal for the curing of concrete?

    <p>50F - 70F (10C - 21C)</p> Signup and view all the answers

    How does concrete act as insulation during a fire?

    <p>By retaining and releasing heat slowly</p> Signup and view all the answers

    What is a common form of construction used with precast concrete?

    <p>Tilt-up construction</p> Signup and view all the answers

    What strategy is recommended to minimize complications in the hardening of concrete?

    <p>Pouring concrete in batches</p> Signup and view all the answers

    Which factor affects the fire resistance of a concrete assembly?

    <p>Depth of concrete cover over reinforcing bars</p> Signup and view all the answers

    What is the purpose of compression testing in concrete quality assessment?

    <p>To assess the compression strength of a batch</p> Signup and view all the answers

    What role does proper moisture play in the hardening of concrete?

    <p>Affects the final strength of the concrete</p> Signup and view all the answers

    What is the purpose of proper curing in concrete?

    <p>To keep the concrete moist until it reaches desired strength</p> Signup and view all the answers

    What is the function of a superplasticizer when added to concrete mix?

    <p>Make the concrete more workable with less water</p> Signup and view all the answers

    Which type of concrete reinforcement involves embedding steel reinforcement bars or mesh within the concrete?

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

    How does concrete act as insulation during a fire?

    <p>It retains heat and releases it slowly</p> Signup and view all the answers

    What is the primary effect of spalling on concrete?

    <p>Weakens the structure and exposes reinforcing steel</p> Signup and view all the answers

    In prestressing concrete, what does the process aim to achieve by tightening the reinforcing steel?

    <p>Add compressive stresses to the surrounding concrete</p> Signup and view all the answers

    Which type of concrete frame system does not rely on beams for support?

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

    Which reinforcement method involves using steel strands stretched between anchors and then placing concrete around them?

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

    What factor affects the fire resistance of a concrete assembly?

    <p>The density and thickness of the concrete</p> Signup and view all the answers

    What is the main disadvantage of cutting through reinforcing steel during fire fighting operations in reinforced concrete structures?

    <p>Decreases structural stability</p> Signup and view all the answers

    In precast concrete construction, what is a disadvantage of transportation?

    <p>Increased cost due to transportation</p> Signup and view all the answers

    Why is it essential for the design engineer to specify the number, size, and depth of concrete cover around reinforcing bars?

    <p>To ensure adequate strength and durability</p> Signup and view all the answers

    What distinguishes a flat-slab concrete frame from a flat plate system?

    <p>Absence of beams for support</p> Signup and view all the answers

    Which property of concrete makes it vulnerable to failure when exposed to tensile forces?

    <p>Inadequate reinforcing elements</p> Signup and view all the answers

    What role do compression tests play in assessing concrete quality?

    <p>To check compression strength</p> Signup and view all the answers

    What role do aggregates play in the properties of concrete?

    <p>Aggregates provide volume and stability</p> Signup and view all the answers

    What does proper temperature maintenance aim to achieve during concrete curing?

    <p>Avoid excessive heat generation during hydration</p> Signup and view all the answers

    Why is it crucial to avoid cutting through reinforcing steel during firefighting operations in post-tensioned concrete structures?

    <p>It maintains structural integrity under fire conditions</p> Signup and view all the answers

    What is the critical aspect of connecting precast structural components in a building?

    <p>Resisting horizontal forces by lateral tying</p> Signup and view all the answers

    Why is post-tensioned reinforcement preferred over pretensioned reinforcement in terms of assembly life?

    <p>Post-tensioning reduces the risk of concrete corrosion over time.</p> Signup and view all the answers

    What is the primary reason for covering reinforcing strands with grease or plastic tubing in post-tensioning?

    <p>To prevent the strands from bonding with the concrete</p> Signup and view all the answers

    How does improper curing affect the finished surface of concrete?

    <p>It leads to a rough and porous finish.</p> Signup and view all the answers

    What can happen if basic materials such as aggregates used in concrete have a wide range of quality and features?

    <p>The quality of the concrete may vary, impacting its strength and durability.</p> Signup and view all the answers

    In what scenario would poor-quality concrete most likely be used?

    <p>Non-load-bearing applications such as decorative items</p> Signup and view all the answers

    What role does water play in concrete that has an excessive water-to-cement ratio?

    <p>Negatively impacts ultimate strength</p> Signup and view all the answers

    Why are precast and cast-in-place concrete differentiated in terms of design strength development?

    <p>Precast concrete achieves its design strength before placement.</p> Signup and view all the answers

    How does excessive vibration affect concrete quality?

    <p>Causes segregation of materials</p> Signup and view all the answers

    What is a potential consequence of using sand from an ocean beach in concrete production?

    <p>Increased risk of corroding reinforcing steel over time</p> Signup and view all the answers

    Why is it vital to exercise great care in mixing, placing, and curing concrete?

    <p>To guarantee good quality and durability of the final product</p> Signup and view all the answers

    Why can prestressed concrete systems be more vulnerable to failure compared to ordinary reinforced concrete?

    <p>The steel used can yield at lower temperatures</p> Signup and view all the answers

    What is the primary reason for covering reinforcing strands with grease or plastic tubing during post-tensioning?

    <p>To prevent corrosion of the strands</p> Signup and view all the answers

    How does excessive vibration during concrete pouring affect its quality?

    <p>Makes heavy aggregates settle at the bottom</p> Signup and view all the answers

    What is the primary effect of spalling on concrete structures?

    <p>Reduces the durability of the structure</p> Signup and view all the answers

    What role does water-to-cement ratio play in determining concrete strength?

    <p>The single most important factor in determining ultimate strength</p> Signup and view all the answers

    Why is using sand from an ocean beach discouraged in concrete production?

    <p>Introduces salt into the mix, which can corrode steel reinforcement</p> Signup and view all the answers

    What reaction occurs when water is added to cement in concrete mixes?

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

    What happens if aggregates used in concrete have a wide range of quality and features?

    <p>The quality and durability of the concrete can be compromised</p> Signup and view all the answers

    What is the primary purpose of adding admixtures to concrete?

    <p>Enhancing the workability of the concrete mix</p> Signup and view all the answers

    In what situation is reinforced concrete particularly vulnerable due to its material properties?

    <p>Under tensile forces</p> Signup and view all the answers

    What distinguishes prestressing from ordinary reinforcing in concrete construction?

    <p>Prestressing involves stretching steel strands to preload the concrete while ordinary reinforcing does not</p> Signup and view all the answers

    Why is it essential to avoid cutting through reinforcing steel during firefighting in post-tensioned concrete structures?

    <p>To avoid releasing the post-tensioned element and risking structural failure</p> Signup and view all the answers

    Which process aims to place concrete in compression before applying loads to it?

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

    What is the main purpose of ordinary reinforcing bars (rebar) in concrete construction?

    <p>To resist tensile forces in the structure</p> Signup and view all the answers

    Which type of concrete has a significant advantage due to its good insulating properties and noncombustible nature?

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

    What is the purpose of vertical reinforcing bars (stirrups) in concrete construction?

    <p>To provide stability against diagonal tension</p> Signup and view all the answers

    Why is prestressing considered a more efficient use of concrete compared to ordinary reinforcing?

    <p>It places concrete in compression before loads are applied</p> Signup and view all the answers

    What is the purpose of keeping concrete moist during the curing process?

    <p>To help the concrete achieve its desired strength</p> Signup and view all the answers

    What strategy can be used to minimize complications related to heat of hydration in concrete?

    <p>Pour concrete in batches and allow each to cure before adding more</p> Signup and view all the answers

    In fire resistance testing, which type of concrete is considered a better insulator against heat than ordinary concrete?

    <p>Structural lightweight concrete</p> Signup and view all the answers

    What is the primary cause of spalling in concrete when exposed to extreme temperatures?

    <p>Expansion of moisture within the concrete</p> Signup and view all the answers

    Which type of construction involves casting concrete panels on-site and then tilting them into position?

    <p>Tilt-up construction</p> Signup and view all the answers

    What type of structural system consists of a concrete slab supported by closely spaced concrete beams?

    <p>One-way reinforced slab</p> Signup and view all the answers

    In precast concrete construction, what is a significant disadvantage related to transportation?

    <p>It limits the dimensions of precast shapes that can be transported</p> Signup and view all the answers

    What role does heat play in causing structural weaknesses in concrete during a fire?

    <p>Heat generates internal steam pressure</p> Signup and view all the answers

    Which factor contributes to fire-resistance ratings in concrete structural systems?

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

    What is the primary reason for using drop panels or mushroom capitals in flat-slab concrete frame construction?

    <p>To prevent shear stresses in the slab</p> Signup and view all the answers

    More Like This

    Construction Material and Properties Quiz
    25 questions

    Construction Material and Properties Quiz

    CheerfulLaboradite avatar
    CheerfulLaboradite
    Construction Aggregates Quiz
    10 questions

    Construction Aggregates Quiz

    VersatileNewYork avatar
    VersatileNewYork
    Aggregate Properties Quiz
    16 questions

    Aggregate Properties Quiz

    UndisputedRomanticism9150 avatar
    UndisputedRomanticism9150
    Construction Materials Quiz: Aggregates
    48 questions

    Construction Materials Quiz: Aggregates

    GlisteningButtercup avatar
    GlisteningButtercup
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser