CMT Lesson 3

TOPIC 3: PROPERTIES OF MATERIALS


The Properties

Physical Properties

  • characteristic of matter 

  •  not associated with a change in its

chemical composition.


Mechanical Properties

  • determine the range of usefulness of a material 

  • establish the service life that can be expected.


Chemical Properties

  • observed when a substance undergoes a chemical change.


Electrical Properties

  • to conduct or to resist electricity through them are electrical properties of material.


Magnetic Properties

  • refers to the behavior of a material when subjected to a magnetic field

  • those which determine the ability of material to be suitable for a particular magnetic Application.


Thermal Properties

  • govern the rate of heat transfer between the inside and outside of the building



PHYSICAL PROPERTIES

Density

  • the dry mass per unit volume of a substance under absolute compact conditions.


Bulk Density

  • mass per unit volume of substance

  • material in its natural state with pores and

voids.


Density Index

  • ratio of bulk density and density.

  • the volume of a material is filled with solid matter.


Specific Weight

  • the unit weight per unit volume of material

  • ratio of density of the solid material and the density of distilled water at a temperature ((+4C°).

  • density of distilled water at this temperature is

equal (1 g/cm3 ) or (1000 kg/m3).


Specific Gravity

  • ratio of weight/mass of a given volume of solids to the weight/mass of an equal volume of water at 4°C


True or Absolute Specific Gravity

  • the specific gravity if both the permeable and impermeable voids are excluded to determine the true volume of solids


Apparent or Mass Specific Gravity

  • the specific gravity if both the permeable and impermeable voids are included to determine the true volume of solids


Porosity

  • the volume of the material is interspersed with pores.

  • expressed as a ratio of the volume of pores to

that of the specimen.


Void Ratio

  • ratio between the volume of voids to the

volume of solid material


Hygroscopicity

  • property of a material to absorb water vapor from air.

  • expressed by moisture content.

  • property of a material to absorb water vapor from the air.


Water Absorption

  • water are exposed to water.

  • expressed by the water-absorption ratio.


Weathering Resistance

  • ability of a material to endure alternate wet and dry conditions for a long period


Water Permeability

  • capacity of a material to allow water to penetrate under pressure.


Water Impermeability

  • the ability of a material to resist the pressure of water or the infiltration of other liquids. 

  • Materials like glass, steel, and bitumen are impervious.


Frost Resistance

  • the ability of water-saturated material to endure repeated freezing and thawing


Thermal Capacity

  • the property of a material to absorb heat when  it is heated and to release heat when it is cooled. 


Thermal Deformation

  • the property of a substance to expand with heat and contract with cold.


Flame Resistance

  • the property of a substance not to flame in case of contacting with fire in the air.


  • Non-Flammable Materials

  • cannot be fired, carbonized or slightly burned when contacting with fire 


  • Fire-Retardant Materials

    • hard to be burned or carbonized when contacting with fire 

    • stop burning or slightly flaming immediately when leaving the fire.


  • Flammable Materials

    • ignited or flame immediately when contact with fire

    • continue to burn or slightly flame when leaving the fire.


Heat Conductivity

  • ability of a material to conduct heat


Refractoriness

  • to withstand prolonged action of high temperature without melting or losing shape.


Chemical Resistance

  • to withstand the action of acids, alkalis, seawater, and gases.


Durability

  • to resist the combined effects of atmospheric

pressure and other factors.


Spalling Resistance

  • ability of a material to undergo a certain number of cycles of sharp temperature variations without failing.

  • describe areas of concrete which have cracked


Coefficient of Softening

  • the ratio of compressive strength of a saturated material to its compressive strength in dry state.

  • affects the strength of water absorbent materials like soil.


Refractoriness

  • the property of a material which cannot melt or lose its shape at prolonged high temperatures (1580 C or more).



MECHANICAL PROPERTIES


Strength

  • greatest stress

  • substance can bear under external force (loads) without destruction.


Elasticity

  • deform with external forces 

  • return to its original shape when the stress is removed.


Plasticity

  • describes the deformation of a material undergoing nonreversible changes of shape 

  • ability of material to change its shape under load without cracking and to retain this shape after the load is removed


Brittleness

  • fractures when subjected to stress but has little tendency to deform before rupture.


Toughness

  • impacted or vibrated by stress

  • material is able to absorb much energy

and deform greatly without rupture. 

  • Also called impact toughness.


Hardness

  • property of a material to resist pressing-in or scratch of a sharp object.


Abrasive Resistance

  • capacity of a material to resist abrasion.

  • an ability to withstand the wear and tear of

friction caused by mechanical parts


Fatigue

  • material is subjected to repeated loads, then the failure occurs at some point which is lower than the failure point caused by steady loads.


Impact Strength

  • a material is subjected to sudden loads and it will undergo some deformation without causing rupture

  • designates the toughness of material.


Creep

  • deformation caused by constant loads for long periods.


CHEMICAL PROPERTIES


Corrosion Resistance

  • material's ability to withstand degradation or deterioration caused by chemical reactions with its environment

  • such as oxidation, rusting, or acidic attack.


Corrosion

  • Formation of rust (iron oxide) in metals, when they are subjected to atmosphere


Ph Sensitivity

  • affect their chemical stability and performance.


Reaction With Water

  • certain materials undergo chemical reactions with water, leading to hydration, expansion, or dissolution.


Compatibility With Adjacent Material

  • essential to prevent adverse chemical interactions.


Chemical Resistance To Aggressive Substances

  • Materials should possess resistance to aggressive substances encountered in their intended applications

  • such as industrial chemicals, sewage, and aggressive soils.


THERMAL PROPERTIES


Thermal Capacity

  • the property of a material to absorb heat and it is required to design proper ventilation.


Thermal Conductivity

  • amount of heat transferred through unit area of specimen with unit thickness in unit time


Thermal Resistivity

  • the ability to resist heat conduction


Specific heat

  • the quantity of heat required to heat 1 N of material by 1oC.

  • useful when we use the material in high temperature areas.



PROPERTIES OF MOST COMMONLY USED CONSTRUCTION MATERIALS

  1. ASPHALT

  • Durability

  • Rheology

  • Safety

  • Purity

  1. STEEL

  • Strength

  • Toughness

  • Ductility - redistribution of stress at the ultimate limit state