CE 241 MATERIALS SCIENCEIntroductionCE 241 MATERIALS SCIENCEIntroduction
What do Engineers do?What do Engineers do?
Design and Build ....Design and Build ....
As Civil Engineers we design and build civilstructures (residental buildings, hospitals, dams,roads, towers, ...)As Civil Engineers we design and build civilstructures (residental buildings, hospitals, dams,roads, towers, ...)
Materials Science and Engineering forms thebedrock for the engineering disciplines becausethe structures, components, and devices thatengineers design and use must be made out ofsomething, and that is a material.Materials Science and Engineering forms thebedrock for the engineering disciplines becausethe structures, components, and devices thatengineers design and use must be made out ofsomething, and that is a material.
The properties of the materials that are availabledefine and limit the capabilities that the device orstructure can have, and the techniques that can beused to fabricate it.The properties of the materials that are availabledefine and limit the capabilities that the device orstructure can have, and the techniques that can beused to fabricate it.
Reinforced Concrete Bridges... ~5-10 m in spanReinforced Concrete Bridges... ~5-10 m in span
Prestressed Concrete Bridges... ~ 30-40 m in spanPrestressed Concrete Bridges... ~ 30-40 m in span
Steel Bridges... ~ 60-70 m in spanSteel Bridges... ~ 60-70 m in span
Selecting the best material is usually a difficult task,requiring tradeoffs between different materialproperties (including cost)Selecting the best material is usually a difficult task,requiring tradeoffs between different materialproperties (including cost)
Cost of a residential building:Cost of a residential building:
65-75% materials cost65-75% materials cost
5% technical personel5% technical personel
Rest is the labor costRest is the labor cost
Therefore, an appreciation of theTherefore, an appreciation of the
important materials characteristics,important materials characteristics,
the connection between the behavior of thematerial in its intended design setting,the connection between the behavior of thematerial in its intended design setting,
and the stuff the object is made from (and how it ismade)and the stuff the object is made from (and how it ismade)
is important to every engineer, even if they will nevercreate a new material but simply choose fromstandard and widely available ones.is important to every engineer, even if they will nevercreate a new material but simply choose fromstandard and widely available ones.
As civil engineers our job is to:As civil engineers our job is to:
To make sure that the structure is functional during itsservice life (it should be strong)To make sure that the structure is functional during itsservice life (it should be strong)
To make sure that the structure should withstand theenvironment (it should be durable)To make sure that the structure should withstand theenvironment (it should be durable)
To make sure that the structure is aesthetic andeconomic (it should be feasible)To make sure that the structure is aesthetic andeconomic (it should be feasible)
We need to know the properties of constructionalmaterials.We need to know the properties of constructionalmaterials.
Physical, chemical and mechanical propertiesPhysical, chemical and mechanical properties
Manufacturing processesManufacturing processes
Its behavior in its final formIts behavior in its final form
The service life of a civil engineering structuredoes not ONLY depend onThe service life of a civil engineering structuredoes not ONLY depend on
How good its design isHow good its design is
How good its labor isHow good its labor is
You have to consider other factors such as:You have to consider other factors such as:
How good the material that you pick isHow good the material that you pick is
How good the quality control isHow good the quality control is
How you maintain the structure!How you maintain the structure!
Think about the maintenance requirements ofThink about the maintenance requirements of
your car !your car !
your house !your house !
Why do we need to know materials?Why do we need to know materials?
Every engineer, whether mechanical, civil,chemical or electrical, will at some point dealwith a design problem involving materials.Examples might include a transmission gear, thesuperstructure of a building, an oil refinerycomponent, or an integrated circuit chip.Every engineer, whether mechanical, civil,chemical or electrical, will at some point dealwith a design problem involving materials.Examples might include a transmission gear, thesuperstructure of a building, an oil refinerycomponent, or an integrated circuit chip.
To conclude:To conclude:
Materials ScienceMaterials Science
Materials Science: The study of the nature,behavior and use of materials.Materials Science: The study of the nature,behavior and use of materials.
The purpose of this course is to:The purpose of this course is to:
Learn the properties of materialsLearn the properties of materials
(strength, ductility, impact resistance, ...)(strength, ductility, impact resistance, ...)
Learn the internal structure of materialsLearn the internal structure of materials
(the atomic structure, bonding, ...)(the atomic structure, bonding, ...)
Learn how the internal structure of a materialaffects its propertiesLearn how the internal structure of a materialaffects its properties
Metals: Metallic bonding ductilityMetals: Metallic bonding ductility
Ceramics: Ionic and covalent bods brittlenessCeramics: Ionic and covalent bods brittleness
Plastics: Covalent and Van der Waals bondsmoistureresistancePlastics: Covalent and Van der Waals bondsmoistureresistance
Properties of MaterialsProperties of Materials
Mechanical : Define the behavior of the materials underloads. (Strength, elasticity, plasticity, ductility, hardness,etc.)Mechanical : Define the behavior of the materials underloads. (Strength, elasticity, plasticity, ductility, hardness,etc.)
Physical : Density, porosity, moisture content, shape,surface texture, etc.Physical : Density, porosity, moisture content, shape,surface texture, etc.
Chemical : Oxide or compound compositionChemical : Oxide or compound composition
Physico-chemical : Shrinkage, swellingPhysico-chemical : Shrinkage, swelling
Thermal : ConductivityThermal : Conductivity
Acoustical : Sound transmission or absorptionAcoustical : Sound transmission or absorption
Optical : ColorOptical : Color
Classification ofCivil Engineering MaterialsClassification ofCivil Engineering Materials
This classification can be done in so manydifferent ways:This classification can be done in so manydifferent ways:
According to their stateAccording to their state
According to their chemical composition andinternal structureAccording to their chemical composition andinternal structure
According to their intended useAccording to their intended use
According to their mechanical behaviorAccording to their mechanical behavior
1. According to Their State1. According to Their State
Gases (CO2, O2)Gases (CO2, O2)
Liquids (Water, Chemical Admixtures)Liquids (Water, Chemical Admixtures)
Solids (Concrete, Steel)Solids (Concrete, Steel)
Semi-solids (Fresh Pastes, Mortar, Concrete)Semi-solids (Fresh Pastes, Mortar, Concrete)
2. According to Their ChemicalComposition and Internal Structure2. According to Their ChemicalComposition and Internal Structure
Metals → Metallic bondMetals → Metallic bond
Ferrous (Iron, steel)Ferrous (Iron, steel)
Non-ferrous (Aluminum)Non-ferrous (Aluminum)
Polymers → Long chain moleculesPolymers → Long chain molecules
Natural (rubber, resin, wood)Natural (rubber, resin, wood)
Artificial (plastics)Artificial (plastics)
Ceramics → Alumino silicatesCeramics → Alumino silicates
Structural clay productsStructural clay products
PorcelainsPorcelains
Composite Materials → combination of several materialsComposite Materials → combination of several materials
ConcreteConcrete
Cement sandstoneCement sandstone
Reinforced Composite MaterialsReinforced Composite Materials
Reinforced concreteReinforced concrete
Fiber reinforced plasticsFiber reinforced plastics
3. According to Their Intended Use3. According to Their Intended Use
Structural Materials (concrete, steel, wood)Structural Materials (concrete, steel, wood)
Architectural Detailing Materials (glass, paint,heat and sound insulators)Architectural Detailing Materials (glass, paint,heat and sound insulators)
Preservatives (paint)Preservatives (paint)
But some materials fall into all of the abovegroups for example wood.But some materials fall into all of the abovegroups for example wood.
•Load carrying member•Load carrying member
•Architectural•Architectural
•Coating of chipboard•Coating of chipboard
4. According to Their MechanicalBehavior4. According to Their MechanicalBehavior
Elastic MaterialsElastic Materials
They deform under some load and when theload is removed they return back to theiroriginal positionThey deform under some load and when theload is removed they return back to theiroriginal position
Load
Deformation
Plastic MaterialsPlastic Materials
They deform under some load, but whenthe load is removed there will be somepermanent deformationThey deform under some load, but whenthe load is removed there will be somepermanent deformation
δ
P
δperm: Permanent Deformation
Viscoelastic MaterialsViscoelastic Materials
The load-deformation depends on the rate ofloadingThe load-deformation depends on the rate ofloading
Load
Deformation