45 Questions
What is the unit of Young's modulus?
N/mm²
What happens to the shape of an elastic material when the load is removed?
It recovers its original shape
What is the proportional constant between normal stress and normal strain called?
Young's modulus
What is the purpose of structural materials in building construction?
To resist loads and support the structure
What is the characteristic of a material with a high Young's modulus?
It is difficult to deform
What is the unit of measurement for density?
g/cm3
Which of the following is an example of a plastic material?
Clay
What is the formula for calculating apparent density?
M/V°
What is the formula to calculate Young's modulus?
E = σ/ε
What is the difference between density and apparent density?
Density is for materials under absolute compact conditions, while apparent density is for materials under natural conditions
What is the effect of applying a tensile stress on the diameter of a steel bar?
It decreases
What is the effect of applying a tensile stress on the distance between two points on a steel bar?
It increases
What is bulk density used to describe?
The dry mass per unit volume of a substance under packing conditions
What is the characteristic of a material with a low Poisson's ratio?
It has low lateral strain
What is the unit of measurement for unit weight?
N/m3
What is the formula for calculating unit weight?
M*g/V
What is the relationship between unit weight and density?
Unit weight is directly proportional to density
What is the purpose of nonstructural materials in building construction?
To partition spaces
What is the ability of a material to resist the action of high temperature without any appreciable deformation and substantial loss of strength?
Fire resistance
What is the ability of a material to withstand the action of acids, alkalis, seawater and gases?
Chemical resistance
What is the primary characteristic that thermal conductivity of a material indicates?
Its ability to conduct heat
What is the property of a material to resist pressing-in or scratch of a sharp object?
Hardness
What is the reciprocal of thermal conductivity?
Thermal resistance
What is the formula to calculate the abrasion ratio?
𝑁 = (𝑚1 - 𝑚2)/𝐴
What is the term for the ability of a material to resist the combined effects of atmospheric and other factors?
Durability
What is the term for the amount of expansion per unit length due to one unit of temperature increase?
Linear coefficient of thermal expansion
What is the unit of the abrasion ratio?
gm./cm2
Why are joints used in buildings, bridges, and concrete pavements?
To accommodate thermal expansion and contraction
What is the likely consequence of steel and concrete having different coefficients of thermal expansion?
Fracture and cracking
What is the term for the ability of a material to resist abrasion?
Abrasive resistance
What is the significance of the abrasion ratio in evaluating building materials?
It evaluates the material's durability
What is the primary reason for using materials with low thermal conductivity?
For thermal insulation
What is the formula for calculating the linear coefficient of thermal expansion?
$\frac{\delta L}{\delta T*L}$
What is the relationship between the mass before and after abrasion in calculating the abrasion ratio?
m1 > m2
What is the significance of the linear coefficient of thermal expansion (αL) in structural materials?
It determines the rate of thermal expansion
What is the likely effect of a temperature decrease on a steel bar fixed at both ends?
It will experience tension
What is the defining characteristic of elasto-plastic materials?
Ability to recover part of changes in shape after removal of loading
What happens to the strain of a material that exhibits linear elastic behavior when the stress is increased beyond a certain point?
The strain will increase with little additional stress
What is the yield strength of the aluminum alloy rod in the example?
150 MPA
What is the change in gauge length of the aluminum alloy rod?
100.1 mm - 100 mm
What is the type of material that exhibits both elastic and plastic behavior?
Elasto-plastic material
What can be inferred from a stress-strain curve that has a linear portion followed by a non-linear portion?
The material exhibits linear elastic behavior followed by plastic response
What is the purpose of drawing a stress-strain curve?
To illustrate the behavior of a material under different loads
What is the relationship between stress and strain in the elastic region of a stress-strain curve?
Stress is directly proportional to strain
What happens to the deformation of a material when the load is removed?
Some of the deformation is recovered, and some remains
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.
Learn about the different classification of building materials, including structural materials, and more. Understand the functions and characteristics of various building materials.
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