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Questions and Answers
Which classification of metals includes materials where the principal element is iron?
Which classification of metals includes materials where the principal element is iron?
Concrete is classified under which type of material production?
Concrete is classified under which type of material production?
What property of materials relates to their ability to resist external dynamic forces?
What property of materials relates to their ability to resist external dynamic forces?
Which of the following is a non-ferrous metal?
Which of the following is a non-ferrous metal?
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Which physical property relates to a material's ability to absorb sound?
Which physical property relates to a material's ability to absorb sound?
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What is NOT a classification criterion for construction materials based on their properties?
What is NOT a classification criterion for construction materials based on their properties?
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Which of the following materials is an example of a naturally occurring material?
Which of the following materials is an example of a naturally occurring material?
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Which property of materials is concerned with their durability against chemical reactions?
Which property of materials is concerned with their durability against chemical reactions?
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What internal phenomenon occurs alongside the development of internal resisting forces when a solid body is under load?
What internal phenomenon occurs alongside the development of internal resisting forces when a solid body is under load?
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Which mechanical test specifically measures the ability of a material to withstand compressive stress?
Which mechanical test specifically measures the ability of a material to withstand compressive stress?
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Which type of stress is primarily assessed during a shear test?
Which type of stress is primarily assessed during a shear test?
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What sets dynamic tests apart from static tests in material examination?
What sets dynamic tests apart from static tests in material examination?
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What is the primary distinction of destructive tests compared to non-destructive tests?
What is the primary distinction of destructive tests compared to non-destructive tests?
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In the context of bending tests, what characterizes the resulting stresses within the specimen?
In the context of bending tests, what characterizes the resulting stresses within the specimen?
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Which mechanical characteristic can be evaluated through fatigue tests?
Which mechanical characteristic can be evaluated through fatigue tests?
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During which type of test are the specimens subjected to prolonged loading over an extended time?
During which type of test are the specimens subjected to prolonged loading over an extended time?
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What does the tensile stress $ au_t$ denote in the context of a standard tension test?
What does the tensile stress $ au_t$ denote in the context of a standard tension test?
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Which property corresponds to the greatest stress a material can withstand without permanent deformation?
Which property corresponds to the greatest stress a material can withstand without permanent deformation?
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In the stress-strain diagram, which point indicates the yield point for ductile materials?
In the stress-strain diagram, which point indicates the yield point for ductile materials?
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What does the modulus of elasticity represent in a material's stress-strain behavior?
What does the modulus of elasticity represent in a material's stress-strain behavior?
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What is the formula for calculating strain ε in a standard tension test?
What is the formula for calculating strain ε in a standard tension test?
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Non-destructive tests are primarily used for which purpose?
Non-destructive tests are primarily used for which purpose?
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During a standard tension test, what is measured alongside the applied load?
During a standard tension test, what is measured alongside the applied load?
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For ductile materials, what characterizes the behavior at the yield point?
For ductile materials, what characterizes the behavior at the yield point?
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What does the initial-tangent modulus represent in a non-linear stress-strain curve?
What does the initial-tangent modulus represent in a non-linear stress-strain curve?
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How is the secant modulus defined?
How is the secant modulus defined?
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Which modulus is defined as the slope of the tangent to the stress-strain curve at a specific point?
Which modulus is defined as the slope of the tangent to the stress-strain curve at a specific point?
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What property indicates that a material has higher stiffness?
What property indicates that a material has higher stiffness?
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What characteristic defines Poisson's Ratio?
What characteristic defines Poisson's Ratio?
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What does ultimate strength refer to in material science?
What does ultimate strength refer to in material science?
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How does the stiffness of steel alloys compare to aluminum alloys based on their moduli of elasticity?
How does the stiffness of steel alloys compare to aluminum alloys based on their moduli of elasticity?
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What is a defining feature of materials in the plastic range?
What is a defining feature of materials in the plastic range?
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Study Notes
Course Information
- Course Title: Construction Materials
- Course Code: CENG 2092
- University: Addis Ababa Science and Technology University
- Date: November 2024
Chapter One: Nature & Properties of Materials
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Contents:
- Classification of Materials
- General Properties of Materials
- Nature and Properties of Materials Under Load
1.1 Classification of Construction Materials
- Material: A substance from which something else can be made.
- Examples: Cement, brick, aluminum, soil, water
- Material Engineering: Understanding and reviewing properties and uses of materials in engineering
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Classification Basis:
- Metallic Property
- Physical Nature
- Mode of Production
Classification Based on Metallic Property
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Metallic Materials:
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Ferrous: Metal with iron as the main element.
- Examples: Steel, wrought iron, cast iron
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Non-ferrous: Metal without iron as the main element.
- Examples: Copper, aluminum, lead, zinc
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Ferrous: Metal with iron as the main element.
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Non-metallic Materials:
- Examples: Concrete, timber, stone, lime
Classification Based on Physical Nature
- Solids
- Liquids
- Gases
Classification Based on Mode of Production
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Naturally Occurring:
- Examples: Stone, timber
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Industrially Produced:
- Example: Cement, glass
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Materials Produced at Construction Site:
- Examples: Concrete, mortar
1.2 General Properties of Materials
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Physical Properties:
- Density & specific gravity
- Thermal property
- Acoustic/sound permeability
- Fire resistance
- Porosity
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Chemical Properties:
- Corrosion Resistance
- Combustibility
- Toxicity
- Decay Resistance
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Mechanical Properties:
- Resistance to external static forces (compressive, tensile, bending, shear, torsional strength)
- Resistance to external dynamic forces (impact and vibratory loads)
1.3 Nature and Performance of Materials under Load
- Load Application: Applying force on a solid body under equilibrium.
- Results: Development of internal resisting forces, deformation of the body.
- Stress and Strain: Internal forces and deformation in solid bodies under load.
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Types of stresses (Depending on Arrangement and Direction):
- Tensile stress
- Compressive stress
- Shearing stress
- Bending stress
- Torsional stress
- Combinations
Testing of Materials for Mechanical Properties
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Mechanical Tests: Classified based on external forces:
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Tension Test: Specimen subjected to axial tensile force.
- Tensile stress on cross-section perpendicular to force.
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Compression Test: Specimen subjected to axial compressive force.
- Compressive stress on specimen.
- Shear Test: Shearing stress on cross-section parallel to force.
- Bending Test: Specimen subjected to forces causing bending moments.
- Torsion Test: Determine torsional strength; specimens usually cylindrical.
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Tension Test: Specimen subjected to axial tensile force.
Tests Based on Load Application Rate & Duration
- Static Tests: Gradually increasing load.
- Dynamic Tests: Suddenly applied loads.
- Wear Tests: Resistance to abrasion and impact.
- Long-Time Tests: Loads applied for a long period.
- Fatigue Tests: Fluctuating stresses repeated many times.
Tests Based on Effect on the Specimen
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Destructive Tests: Specimen damaged or destroyed.
- Examples: Ultimate strength of steel, Compressive strength of concrete
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Non-destructive Tests: Specimen not damaged.
- Example: Hammer test
2.4 Stress-Strain Properties in Simple Tension Test
- Tension Test: Specimen subjected to gradual increasing axial tensile force.
- Change in Length: Measured at various load increments.
- Stress Calculation: Stress = load/cross-sectional area.
- Strain Calculation: Strain = change in length/original length
- Stress-Strain Diagram: Plotted to show relationship between stress and strain.
Properties in the Elastic Range
- Proportional Limit: Maximum stress with no deflection from Hook's law.
- Elastic Limit: Maximum stress without permanent deformation.
- Yield Point: Stress where significant increase in strain occurs with no increase in stress
Modulus of Elasticity
- Young's Modulus: Slope of the initial linear portion of the stress-strain diagram; measure of material stiffness.
-
Methods for Finding Modulus of Elasticity:
- Ductile materials with linear stress-strain.
- Non-linear stress-strain curves; initial tangents, secant, and tangents along curves.
Stiffness
- Ability of material to resist deformation
- Higher modulus of elasticity = stiffer material.
- Steel alloys are stiffer than aluminum alloys.
Poisson's Ratio
- Ratio of transverse strain to longitudinal strain (within proportional limit).
- Measures material stiffness in direction perpendicular to load.
Properties in the Plastic Range
-
Ultimate Strength: Maximum strength before failure.
- Determined by stress-strain relationship
Ductility
- Ability to deform plastically
- Measured by percentage elongation or reduction in area.
Toughness
- Ability of material to absorb energy plastically.
- Materials with high toughness absorb high strain energy in the plastic range.
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Description
This quiz covers essential concepts in material science, including classifications of metals, material properties, and mechanical tests. Test your knowledge on ferrous and non-ferrous metals, sound absorption, and the classifications of construction materials.
