lecture 2. sustainable design, material variability, and ......12/10/2016 8 29 civ-e1010 building...

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CIV-E1010 Building Materials Technology

Lecture 2. Sustainable design, Materialvariability, and Nature of materials

13.09.2016

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CIV-E1010 Building Materials TechnologyFahim Al-Neshawy

Previous lecture

• In the previous lecture wediscussed about:Ø The history of using

building materialsØ Types of materials used

by engineersØ The criteria of selecting

suitable buildingmaterial

Ø the material propertiesimportant to civilengineering:o Structural

characteristicso Physical propertieso Mechanical properties


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2.1 Sustainable design2.1.1 Phases of building materials2.1.2 Features of sustainable building materials

2.2 Material variability2.2.1 Variance of sampling2.2.2 Normal distribution2.2.3 Control charts2.2.4 Experimental error and uncertainty

2.3 Nature of materials - Basic materials concepts2.3.1 Electron configuration2.3.2 Bonding2.3.3 Material classification by bond type

Lecture contents


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1. Knowledge:Ø will be able to learn basic theory about main building- and

construction materials:• material composition / Properties• applications in buildings and structures..

2. Skills:Ø be able to make right and well-founded choice of materials

3. General competence:Ø understand how properties of materials can be related to

the characteristics of the material.

Lecture outcomes

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Sustainable Thinking


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• Sustainable development: is the development that meets the needs ofthe present without compromising the ability of future generations tomeet their own needs.

• The five basic principles of sustainable product design are:1) Cyclic: Products are made from compostable organic materials or

from minerals which are continuously recycled in a closed loop.2) Solar: Products in manufacture and use consume only renewable

energy that is cyclic and safe3) Efficient: Products in manufacture and use require 90% less energy,

materials and water than equivalent products did in 19904) Safe: All releases to air, water, land or space are safe.5) Social: Product manufacture and use supports basic human rights

and natural justice

2.1 Sustainable design


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2.1.1 Phases of building materials

A material’s life cycle can be organized into three phases:

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Pre-Building phase• Describes the production

and delivery process of amaterial up to, but notincluding, the point ofinstallation

• The most potential forcausing environmentaldamage

• Environmentalconsequences:Ø extraction of raw

materialsØ manufacturing processØ Transportation from the

manufacturing locationto the building site

• Understanding the environmentalimpacts in the pre-building phasewill lead to the wise selection ofbuilding materials through thedesign process.

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Building phase• It begins at the point of the

material’s assembly into astructure, includes themaintenance and repair ofthe material, and extendsthroughout the life of thematerial.

• Construction:Ø The material waste generated

on a building construction sitecan be considerable.

Ø The selection of buildingmaterials for reducedconstruction waste.

Ø Waste that can be recycled iscritical in this phase of thebuilding life cycle.

• Use/Maintenance:Ø Long-term exposure to certain

building materials may behazardous to the health of abuilding’s occupants.

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Post-Building phase• refers to the building

materials when theirusefulness in a building hasexpired.Ø At this phase, old

materials may be reusedin its entirety, have itscomponents recycledback into otherproducts, or waste to bereturned to nature.

http://www.remodeling.hw.net/business/construction/thinking-outside-the-dumpster-deconstruction-and-recycling-of-building-materials


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2.1.2 Features of sustainable building materials

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Discussion (5 – 10 min)

Family house• Structural elements?• Select suitable building

materials for each element• Think of sustainable

building materials.• Features of sustainable

building materials:Ø Pre-BuildingØ BuildingØ Post-Building

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(Quality Control)

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2.2 Material variability

Variability is the cumulativeeffect of three types ofvariance:1) The inherent variability of

the material [MATERIAL],2) Variance caused by the

sampling method[SAMPLING], and

3) Variance associated withthe way the tests areconducted [TESTING].

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2.2 Material variability

Understanding of variability• Precision refers to the variability

of repeat measurements undercarefully controlled conditions.

• Accuracy is the conformity ofresults to the true value or theabsence of bias.

• Bias is a tendency of an estimateto deviate in one direction fromthe true value. In other words,bias is a systematic errorbetween a test value and thetrue value.

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2.2.1 Variance of sampling

In order for the samples to bevalid:• They must be randomly

selected.• The sample must be

representative of the entire lot• The sample size needed to

quantify the characteristics ofa population

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Example of Quality Tests OfConcrete• Slump test before leaving

the batching plant and onarrival on site

• Testing for air content• Temperature of freshly

mixed concrete• Compressive strength test

(7, 28, 64 days)

• Water Permeability testàdurability

• Water Absorption testàdurability


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Commonly used statistical parametersdescribe the material properties are:• The mean:Ø Simply the average of test results of all

specimens testedØ It is a measure of the central tendency

of the population• The standard deviation:Ø a measure of the dispersion or spread

of the results.• Coefficient of Variation:Ø A way to combine ‘mean’ and ‘standard

deviation’ to give a more usefuldescription of the material variability.

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2.2.2 Normal distribution

The normal probability distribution is completely described if the average(mean) and the variation of the data (standard deviation) are known.

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2.2.2 Normal distribution

Example of concrete compressive strength• Average Strength, μ = 804/20 = 40.2 MPa• Standard deviation = (359.2/(20-1))^0.5 = 4.34 MPa• Coefficient of Variation = (Standard

deviation/Average strength)*100 = (4.34/40.2)*100= 10.80 %

• 68% of samples have compressive strengthbetween 35.86 and 44.54 MPa

• 95% will be between 31.52 and 48.88

• 99.7% will be between 27.18 and 53.22

# fc (MPa) (x-μ)2

1 43(43 - 40.2)^2 =

7.482 48 60.843 40 0.044 38 4.845 36 16.646 39 1.447 42 3.248 45 23.049 37 10.24

10 35 27.0411 39 1.4412 41 0.6413 49 77.4414 46 33.6415 36 16.6416 38 4.8417 32 67.2418 39 1.4419 41 0.6420 40 0.04

Total 804 359,2

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2.2.3 Control charts

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2.2.4 Experimental error and uncertainty

• Random Errors:These errors areunpredictable broughtabout by things usually outof control.The precision ofmeasurements subject torandom errors can beimproved by repeating thosemeasurements

Types and sources ofexperimental errors• Systematic Errors:

These are errors usuallybrought about by themeasuring equipment (orits operator)à for example:faulty calibration ofmeasuring instruments

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Basic principles of erroranalysis:1) Understand the types and

sources of experimentalerrors,

2) Clearly and correctlyreport measurements andthe uncertainties in thosemeasurements, and

3. Design experimentalmethods and techniquesand improve ourmeasurement skills toreduce experimentalerrors.

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Calculating experimental error:1) Error Formula:

In general, error is thedifference between anaccepted or theoretical valueand an experimental value.

Error = Experimental Value -Known Value

2) Relative Error Formula:

Relative Error = Error / KnownValue

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Discussion (5 – 10 min)

You ordered concrete to castthe foundation of your familyhouse:• Taking concrete samples:

how and why?• What are the statistical

parameters you are lookingfor?

• What kinds of errors areexpected?

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2.3 Nature of materials - Basic concepts

Electron configuration

Bonding

Material classification by bond type

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2.3 Nature of materials - Basic conceptsAs engineers we are primarily concerned with the properties of materials at the

macrostructural levelIn order to understand materials properties, their behavior and to modify them to

our advantage, we need an understanding of the structure of materials at theatomic level through bonding forces, molecules and molecular arrangement.

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2.3.1 Electron configuration - Atoms

• Atoms are the basic building blocks of allmaterials.

• Behavior of materials is dictated by (i) thestructure and (ii) bonding of the atoms

• Atoms consist of three particles:Ø Protons: center of the atom,

positively charged, and with massØ Neutrons: center of the atom, no

charge, equal mass to the protonØ Electrons: - electrons travel around

the nucleus in paths (orbits), havediscrete energy states, tend to occupythe lowest available state, negativelycharged, and negligible mass.

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Orbit levels of electrons in an atom

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Metal ions - give up electrons

http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/atomic/ionicrev2.shtml

Sodium has one electron in itshighest energy level. When this

electron is lost, a sodium ionNa+ is formed

Calcium has two electrons in itshighest energy level. Whenthese electrons are lost, acalcium ion Ca2+ is formed

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Non-Metal ions – gain electrons

http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/atomic/ionicrev2.shtml

Chlorine has seven electrons in itshighest energy level. It gains anelectron from another atom in

reactions, forming a chloride ion, Cl-

Oxygen has six electrons in its highestenergy level. It gains two electrons

from one or two other atoms inreactions, forming an oxide ion, O2-

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2.3.2 Bonding

http://www.kaplaninternational.com/blog/fun-facts-about-james-bond

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2.3.2 Bonding

What are bonds?• A force that holds groups of

2 or more atoms togetherand makes them functionas a unitàmolecule

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2.3.2 Bonding

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2.3.2 Bonding - Ionic bonds [Primary]

https://www.youtube.com/watch?v=VSc491HLzDo

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• Metal to non-metal.• Metal loses electrons to form cation.• Non-metal gains electrons to form anion.



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Generally, solid materials with ionic bonds are:Ø Hard à particles cannot easily slideØ Good insulators à no free electrons or ions (unless

dissolved or melted)Ø Transparent à their electrons are not moving from

atom to atom and less likely to interact with lightphotons.

Ø Brittle à bonds are strongØ Have high melting point à ionic bonds are relatively

strong



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2.3.2 Bonding - Covalent Bonding [Primary]

https://www.youtube.com/watch?v=VSc491HLzDoCIV-E1010 Building Materials Technology

Fahim Al-Neshawy

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2.3.2 Bonding - Covalent Bonding [Primary]

Some common features of materials with covalent bonds:Ø Low enthalpies of fusion and vaporizationØ Good insulatorsØ Solids can be soft or brittleØ If brittle often transparent and cleave rather than

deformØ Good electrical and thermal conductors due to their

free valence electrons

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2.3.2 Bonding - Metallic bonding [Primary]

https://www.youtube.com/watch?v=Bi0rUNV8mEwCIV-E1010 Building Materials Technology

Fahim Al-Neshawy

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2.3.2 Bonding - Metallic bonding [Primary]

Some common features of materials with metallicbonds:• Good electrical and thermal conductors due to their

free valence electrons• non-transparent (läpinäkymätön)• Relatively ductile

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2.3.2 Bonding


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2.3.2 Bonding - Van der Waals bonds [2ndry]

https://www.youtube.com/watch?v=1iYKajMsYPY

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• The main characteristics are:

Ø Weaker than normal ionic, covalent, or metallic bonds.

Ø Additive and cannot be saturated.

Ø Having no directional characteristic.

Ø Short - range forces and hence only interactions between

nearest need to be considered instead of all the

particles.

2.3.2 Bonding - Van der Waals bonds [2ndry]

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2.3.2 Bonding – Hydrogen bonds [2ndry]

https://www.youtube.com/watch?v=aH2IbYs_XjY

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2.3.2 Bonding – Hydrogen bonds [2ndry]

How are they formed?• Hydrogen bonding is the

attraction between ahydrogen atoms of amolecule to an unsharedpair of electrons in anothermolecule.

Strenght.• Hydrogen bonds are

classified as weak bondsbecause they are easily andrapidly formed and brokenunder normal biologicalconditions.

Importance.• Hydrogen bonds are

responsible for the physicalproperties of manybiological substances and,more importantly, water

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2.3.2 Bonding - Understanding bonds

NaCl → 1413 °C

H2O → 100 °C

HCl → -85.05 °C

Boiling / Melting point

Dec

reas

ing

Ionic

Hydrogen/ covalent

Van der Waals

Steel → 2500 °C Metal

Hydrochloride gas

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• Metals : (formed by metallic bonds) generally have acrystalline structure, a repeated pattern or arrangement ofthe atoms

• Organic solids: usually have a random molecular structure.Long chains having molecules of C, H, O, N which areformed by covalent bonding. The chains are bound to eachother either by covalent bonds or Van der Waals forces.

• Inorganic solids: Inorganic solids include all materialscomposed of non-metallic elements or a combination ofmetallic and non-metallic elements.

• Ceramics: Ceramic materials are mainly aluminosilicatesformed by a combination of ionic and covalent bonds.

2.3.3 Material classification by bond type

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2.3.3 Material classification by bond type

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Summary

• Learn about:Ø Sustainable building

materials: what does itmean, their features,and phases of buildingmaterials

Ø Variability in buildingmaterials and somedefinitions relating totheir quality control

Ø Nature of buildingmaterials (atoms,electrons, bonding)

Ø Material classification bybond type

Next Lecture:• Stones & Aggregates

lecture 2. sustainable design, material variability, and ......12/10/2016 8 29 civ-e1010 building...

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