What are the main materials used in constraction?
concrete, steel, polymers
what is the force in newton for a 0.4 tonne mass, consider g=9.81 m/s2
0.4x1000=400kg f=mxg 400x9.81=3924N
=3.4kN
what is stress
the effect of force over a specific area
what is the diffrent types of defamation
Elastic, plastic
what is strain
the ratio of deformation (change) over original
The atom generally consists of
protons
neutrons
electrons
protons are
positive changes, and give the stability for the atoms
the outer sub-shell of atoms can accommodate up to
8 electrons
Atoms tend to bond with each other to form materials
true
whan the same atoms bond, they form
elements
the name of the table that all elements are distributed in is
periodic table
the elements that are in the same raw (period) of the periodic table have
same number of shells
the columns in the periodic table are called groups
element in the same group have
similer properties
what is the bonding type for Ca (2 electrons) & O (6 electrons) (CaO)
Ionic
what is the bonding type of Ethylene C2H4
Covalent
What is the bonding type of Ethane C2H6
The state of material that is incompressible and fills the contniner is
Liquid
The stracture that have very organised atoms arranged in arrays is called
crystal
the 3D unite of crystal structure is called
lattice
polymers are
semi-crystallised material
the main property of the amorphous material is
Transparent
what is the type of crustal structure is this
BCC
what is the lattice structure of iron >910 degrees
FCC
Atoms and molecules are stay alone
False
Solids and liquids can have three structure
Crystal structure is
a very organised arrys of atoms or molecules as repeated units
The main property of amorphous material is transparency
True
What is the type of crystal structure is this
The structure that has the highest slip plans are
BCC, FCC
The more slip plans, the more ductile material is
What is not a defect in crystal structure
Guest atom
interstitial smaller atoms (alloy) in the crystal structure make the material
the quicker cooling the smaller gains size formed
cooling quickly will produce materials that are
hard and brittle
when was the first use of concrete around
7000 BC
What is the name of concrete produced by Roman
pozzolan
Who build the 3rd iteration of eddystone light house
John Smeaton
When was portland cement rogulate by BS
1904
Concrete is
weak in tension and brittle
What are the main components of concrete
Cement, water, couse aggregates, fine aggregate
What are three main components of portland cement
Calcium oxide (CaO) - limestone
silicon Dioxide (silica, Sio2)- clay
Aluminium oxide (A1203)- clay
What is the normal ratios of clay and chalk in the portland cement
1:4 clay : chalk
Arrange the diferent steps of cement manufacturing in the right order
1- Blending and grinding
2- pre heating up to 900 degree
3- kiln to heat the meal to 1800 degree
4- cooling and grinding
What is the main step in cooling and grinding the cement
Adding a gypsum
What is the name of the resulted product from the kiln stage of cement manufacture
Calcming material
What properties cement has by adding blast-furnace stage
less heat, low cost, sulphates risistance
Select the concrete advantages from below
protecting the embed steel,
variety of slopes and fishes,
not expensive nowdays,
high compressive strength
The hydration is the chemical reaction between water and cement to bind the aggregate into a stage hard material
The hydration process is exothermic process
Exothermic process mean
That this process produces heat
the hydration process will remove the
water
The optimal percentage of water (water cement ratio) for the whole cement to be reacted is
43%
The maximum size of fine aggregates is
4.75mm
The aggregates’ shape that gives the strongest concrete is
Anguler
What are additives
materials used to replace past of the cement
Aggregate reduce the concrete cost
The aggregates that used for heavy weight concrete are
Magnetite and lead
in the UK, the percentage of secondary and recycled aggregates used is
29%
which aggregate gives stronger concrete
well grounded aggregated
good grading of different use of cencrete is controlled by which British standards
BS882
the minimum size of coarse aggregates in mm is
4.75
Angular
which below aggregate is used for light weight concrete is
Expanded clay
Admixtures are the additional material used to change one or more of the concrete properties
Which are admixtures
accelerators
retarders
plasticiser
Retarders are used to increase increase inital set strength
The percentage of primary aggregates used for concrete in the UK is
71%
Accelerators are prohibited ro be used in
steel rainforced concrete
they cause rust
what is the meaning of concrete mix design
Determing the quantities of concrete components
which of the following are concrete mix design method
Nominal mix
standard mix
DoE mix
in the nominal method 1:3:5 means
1 cement 3 sand 5 coarse agregates
The longer transportation time the higher workability required
Normal formwork with simple steel needs
low consictence concrete
which elements is the easiest to be compacted
Slabs
What tacters that affectting our workability decision
type of framwork,
transportation time ,
the case of comaction
what is an early age concrete
the first few days after concrete is placed,
compacted and finished
The most important property of the fresh concrete is
workability
Which of the following are a workability test
slamp test
compactability test
flow table test
What is the meaning of fresh concrete
concrete after mixing and during the transportation and placement of concrete but be-fore setting up
what is the main property of fresh concrete
concsistency
what is not the meaning of consistency
cohesiveness
what is the meaning of early age concret
first few days after concrete is placed
what is not a main concern in early age concrete
the workability of concrete
what is the reasons behind early set
insufficient gypsum
incorrect gypsum time
what are the main reason of plastic settlement
the existence of restrains (steel or narrow section)
What is not a method for settlement cracking controls
place in hot weather
How cracks of plastic shrinkage can be controlled
-covering the concrete surface with polythene
-using moister spray
-evaporation retarder
what is the main reson of plastic shrinkage in concrete
water loss
The external restrains of thermal contraction is
pour new concrete on an old one
the main effect of pouring concrete in a cold weather is
slow hydration process
what controls can be taken when having concrete with high temperature
-pour at cooler times of day
-lower concrete tempereture before & during placement
-limit pour size
The dimension of the standard cube in the cube tests are
100x100x100mm
the hight/diameter optimal ratio of a cylinder in a concrete cylinder test is
2:1
The compression failare of concrete is ductile
what is the cylinder stright of concrete of C32/40
32N/mm^2
the symbol used for the cube strength is
fcu, fc
what is fck of a concrete which has fcu=60 N/mm^2 according to BS EN 206-1
49 N/mm^2
what is concrete curing
the process in which the concrete gains strength for loads
what is the main important issue during curing
to limited the water loss
why care should be taken for curing in cold weather
Freezing water and longer curing time
why care should be taken for curing in hot weather
Excessive thermal cracking & weaker concrete
concrete strength is the concern of which consuction party
designers
concrete is very weak in
tension
what are the different concrete comprossion tests
cube and cylinder tests
steel links are used to resist
shear stress
what is the main reason for the initial deformation in the concrete
shrinkage
what are the two main types of shrinkage
thermal and drying
the more aggregates, the more shrinkage
fales
concrete stiffness increases when W/C increases
what is the approximate elastic modulus of a C32/40 concrete with a quartzite agregite
around 31.2 KN/mm^2
what are the two type of deformation
visual and internal
what is the main reason for visual deformation
chemical material
lack of supervision
bed implemen
what are the main reason of concrete physical attack
porosity, permeability and low temperture
New concrete with incomplete hydrate is at risk of physical attack
What are the main chemical attacks of concrete
sulphate
sea water
acid
what are the control that can be taken when we have AC2-AC3 of sulphate attack
low w/c
water proof coating
additives
the main characteristics of pure metals are
soft and ductile
select the metals advantages
the can be alloyed and welded, they are soft and ductile, they are not porous
phase diagram show the relationship between metal composition and pressure
Fales
the same atoms size for the mixed materials, the more complex phase
false
phases (materials) in the phase digram with high temperature are usally
liquid
how many phases we have when we mix lead with tin
6
Week 1
Density
Mass per unit volume
Density=Mass/Volume
Units: kg/m³
Used to fairly compare material weight.
Mass
Amount of matter in an object (kg).
Forces & Loads
Action that causes movement.
F(N)= mass(kg)× g(m/s²)
1 kN = 1000 N
Stress
Stress = Force(N) / Area (mm2)
Types of Stress:
Normal – pulling or pushing
Shear – sliding forces
Torsion – twisting
Bending – load on beam centre
Strain
Strain=Change in length/Original lengthStrain =
No unit
Used to fairly compare deformation
Deformation
Elastic: Returns to original shape
Plastic: Permanent change
Stress–Strain Graph
Stage
Description
Elastic Zone
Linear behaviour, straight line
Yield Point
Start of permanent deformation
Plastic Zone
Non-linear behaviour, permanent change
Young’s Modulus (E)
E=StressStrainE = \frac{Stress}{Strain}E=StrainStress
Measures stiffness
Higher E = stiffer material
Steeper graph
Mechanical Properties
Property
Meaning
Strength
Maximum stress before failure
Hardness
Resistance to plastic deformation
Toughness
Ability to absorb energy without breaking
Creep
Slow deformation under constant load
Fatigue
Failure under repeated loading
Failure Modes
Brittle Failure
Sudden failure
Little plastic deformation
Example: concrete, glass
Ductile Failure
Large plastic deformation
Gives warning before failure
Example: most metals
Week 2
All materials are made from very small particles called atoms. It has the properties of a chemical element and bonds with other atoms to form materials. Atoms are the basic building blocks of chemistry and are a source of potential constructive or destructive energy. Materials that contain only one type of atom are called elements. Elements are arranged in the periodic table based on their electron arrangement. Atoms are mostly empty space.
Atoms
-Made of a nucleus and electrons
-Or made of three subatomic particles: protons, neutrons and electrons
These particles determine the properties of all materials.
Protons
-Positive charge
-Located in the nucleus
-Give the atom its identity (atomic number)
Each element has a unique number of protons
Hydrogen = 1 proton
Carbon = 6 protons
Oxygen = 8 protons
Neutrons
-No charge
-Similar mass to protons
-Affect the atom’s mass but not its chemical properties
-Hydrogen is the only element that can exist without a neutron
The nucleus is held together by a strong force that overcomes the repulsion between positive protons.
Electrons
-Negative charge
-Orbit around the nucleus
-Very small and light
-Number of electrons usually equals number of protons
-Responsible for chemical behaviour
Electrons are arranged in shells around the nucleus.
Electrons move around the nucleus in regions called electron clouds, not in fixed circular paths. The electron cloud is about 10,000 times larger than the nucleus (LiveScience, 2019).
Electrons are arranged in energy levels called shells, which determine an atom’s chemical properties (Britannica, 2020). Each shell can hold a maximum number of electrons:
Shell 1: 2 electrons
Shell 2: 8 electrons
Shell 3: 18 electrons
Shell 4: 32 electrons
The outer shell is important because it affects how atoms react. Most atoms are stable when their outer shell has 8 electrons. However, the first shell is full with only 2 electrons.
For example, Helium has just one shell with 2 electrons, making it chemically stable. Stable elements like helium are called noble gases.
Atoms that do not have a full outer shell are not stable and will bond with other atoms to form elements or compounds.
Elements are arranged in the Periodic Table according to their atomic number. The table was developed by Dmitri Mendeleev.
Periods (horizontal rows) Elements in the same group have the same number of electron shells
Groups (vertical columns)
• Elements in the same group have the same number of electrons in the outer subshell
• Elements in the same group have similar properties
-Electron configuration is chemically stable when outermost subshell is full (8 electrons).
-Noble gases (Neon, Argon, Krypton, Xenon) have a full outer subshell and are very unreactive.
-Atoms will bond together to try to attain full outer subshells.
-When atoms of different elements bond new substances are created - Molecules , Compounds.
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