Building Materials Classification
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Questions and Answers

What is the unit of Young's modulus?

  • Pa
  • KN/mm
  • N/mm² (correct)
  • mm/N

    • What happens to the shape of an elastic material when the load is removed?

  • It changes shape permanently
  • It remains deformed
  • It breaks
  • It recovers its original shape (correct)

    • What is the proportional constant between normal stress and normal strain called?

  • Young's modulus (correct)
  • Stress-strain ratio
  • Poisson's ratio
  • Modulus of elasticity

    • What is the purpose of structural materials in building construction?

    <p>To resist loads and support the structure</p> Signup and view all the answers

    What is the characteristic of a material with a high Young's modulus?

    <p>It is difficult to deform</p> Signup and view all the answers

    What is the unit of measurement for density?

    <p>g/cm3</p> Signup and view all the answers

    Which of the following is an example of a plastic material?

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

    What is the formula for calculating apparent density?

    <p>M/V°</p> Signup and view all the answers

    What is the formula to calculate Young's modulus?

    <p>E = σ/ε</p> Signup and view all the answers

    What is the difference between density and apparent density?

    <p>Density is for materials under absolute compact conditions, while apparent density is for materials under natural conditions</p> Signup and view all the answers

    What is the effect of applying a tensile stress on the diameter of a steel bar?

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

    What is the effect of applying a tensile stress on the distance between two points on a steel bar?

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

    What is bulk density used to describe?

    <p>The dry mass per unit volume of a substance under packing conditions</p> Signup and view all the answers

    What is the characteristic of a material with a low Poisson's ratio?

    <p>It has low lateral strain</p> Signup and view all the answers

    What is the unit of measurement for unit weight?

    <p>N/m3</p> Signup and view all the answers

    What is the formula for calculating unit weight?

    <p>M*g/V</p> Signup and view all the answers

    What is the relationship between unit weight and density?

    <p>Unit weight is directly proportional to density</p> Signup and view all the answers

    What is the purpose of nonstructural materials in building construction?

    <p>To partition spaces</p> Signup and view all the answers

    What is the ability of a material to resist the action of high temperature without any appreciable deformation and substantial loss of strength?

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

    What is the ability of a material to withstand the action of acids, alkalis, seawater and gases?

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

    What is the primary characteristic that thermal conductivity of a material indicates?

    <p>Its ability to conduct heat</p> Signup and view all the answers

    What is the property of a material to resist pressing-in or scratch of a sharp object?

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

    What is the reciprocal of thermal conductivity?

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

    What is the formula to calculate the abrasion ratio?

    <p>𝑁 = (𝑚1 - 𝑚2)/𝐴</p> Signup and view all the answers

    What is the term for the ability of a material to resist the combined effects of atmospheric and other factors?

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

    What is the term for the amount of expansion per unit length due to one unit of temperature increase?

    <p>Linear coefficient of thermal expansion</p> Signup and view all the answers

    What is the unit of the abrasion ratio?

    <p>gm./cm2</p> Signup and view all the answers

    Why are joints used in buildings, bridges, and concrete pavements?

    <p>To accommodate thermal expansion and contraction</p> Signup and view all the answers

    What is the likely consequence of steel and concrete having different coefficients of thermal expansion?

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

    What is the term for the ability of a material to resist abrasion?

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

    What is the significance of the abrasion ratio in evaluating building materials?

    <p>It evaluates the material's durability</p> Signup and view all the answers

    What is the primary reason for using materials with low thermal conductivity?

    <p>For thermal insulation</p> Signup and view all the answers

    What is the formula for calculating the linear coefficient of thermal expansion?

    <p>$\frac{\delta L}{\delta T*L}$</p> Signup and view all the answers

    What is the relationship between the mass before and after abrasion in calculating the abrasion ratio?

    <p>m1 &gt; m2</p> Signup and view all the answers

    What is the significance of the linear coefficient of thermal expansion (αL) in structural materials?

    <p>It determines the rate of thermal expansion</p> Signup and view all the answers

    What is the likely effect of a temperature decrease on a steel bar fixed at both ends?

    <p>It will experience tension</p> Signup and view all the answers

    What is the defining characteristic of elasto-plastic materials?

    <p>Ability to recover part of changes in shape after removal of loading</p> Signup and view all the answers

    What happens to the strain of a material that exhibits linear elastic behavior when the stress is increased beyond a certain point?

    <p>The strain will increase with little additional stress</p> Signup and view all the answers

    What is the yield strength of the aluminum alloy rod in the example?

    <p>150 MPA</p> Signup and view all the answers

    What is the change in gauge length of the aluminum alloy rod?

    <p>100.1 mm - 100 mm</p> Signup and view all the answers

    What is the type of material that exhibits both elastic and plastic behavior?

    <p>Elasto-plastic material</p> Signup and view all the answers

    What can be inferred from a stress-strain curve that has a linear portion followed by a non-linear portion?

    <p>The material exhibits linear elastic behavior followed by plastic response</p> Signup and view all the answers

    What is the purpose of drawing a stress-strain curve?

    <p>To illustrate the behavior of a material under different loads</p> Signup and view all the answers

    What is the relationship between stress and strain in the elastic region of a stress-strain curve?

    <p>Stress is directly proportional to strain</p> Signup and view all the answers

    What happens to the deformation of a material when the load is removed?

    <p>Some of the deformation is recovered, and some remains</p> Signup and view all the answers

    Study Notes

    Classification of Building Materials

    • Building materials can be classified into two main categories: structural and non-structural materials.
    • Structural materials are used to resist loads, such as reinforced concrete and steel used in beams, columns, and foundations.
    • Non-structural materials are not designed to carry loads, such as brick or wood partitions.

    Physical Properties of Building Materials

    • Density (ρ) is the mass per unit volume of a material, calculated as ρ = M / V, where M is the mass and V is the volume.
    • Apparent density (ρ°) is the dry mass per unit volume of a substance under natural conditions, calculated as ρ° = M / V°.
    • Bulk density (ρb) is the dry mass per unit volume of a substance under packed conditions, calculated as ρb = M / Vb.
    • Unit weight (γ) is the weight per unit volume of a material, calculated as γ = W / V or γ = ρ.

    Mechanical Properties of Building Materials

    • Young's modulus (E) is a measure of a material's ability to resist deformation, calculated as E = σ / ε.
    • Different types of modulus of elasticity exist.
    • Poisson's ratio (ν) is a measure of a material's lateral strain response to longitudinal stress.

    Classification of Building Materials by Nature of Deformation

    • Elastic materials can recover their original shape after removal of the load, such as rubber.
    • Plastic materials cannot recover their original shape after removal of the load, such as clay.
    • Elasto-plastic materials can recover part of their shape changes after removal of the load, such as steel, concrete, and wood.

    Thermal Conductivity and Thermal Expansion

    • Thermal conductivity is the ability of a material to conduct heat, influenced by the material's nature, structure, and porosity.
    • Thermal expansion is the change in length of a material due to a change in temperature, calculated as αL = δL / (L * δT).
    • The coefficient of thermal expansion (αL) is a material constant.

    Other Properties of Building Materials

    • Fire resistance is the ability of a material to resist high temperatures without appreciable deformation and substantial loss of strength.
    • Chemical resistance is the ability of a material to withstand the action of acids, alkalis, seawater, and gases.
    • Durability is the ability of a material to resist the combined effects of atmospheric and other factors.
    • Hardness is the property of a material to resist pressing-in or scratch of a sharp object.
    • Abrasive resistance is the capacity of a material to resist abrasion, calculated as N = (m1 - m2) / A.

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