Building MaterialsBuilding MaterialsBuilding MaterialsBuilding Materials

Lecture 2Lecture 2

P ti f B ildiP ti f B ildiProperties of Building Properties of Building M t i lM t i lMaterialsMaterials

B i h i l tiBasic physical properties

= related to mass and volume of the t i lmaterial

• density (specific gravity, specific weight)• bulk densitybulk density• porosity

l t• granulometry• fineness

MassMassChoice of suitable scales:• capacity (max. range)p y ( g )• readability

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ScalesScalesMechanical , digitalec a ca , d g a• analytical (readability 10-4 g, capacity to

200g)200g)• milligram (0,01 g)• laboratory (0,1 - 0,2 g, 200 – 1000 g)• commercial (2 5 5 25 k )• commercial (2 - 5 g, 5 - 25 kg)• industrial (hundreds of kg)

SizeSize

Length measuring devices: calibrable

• Steel rule• Steel measuring tape• Calliper• Calliper• Micrometer• Sieves

VolumeVolumeSolids:Solids:• Count from sizes • Immersion in liquid

– graduated cylinderg y– pycnometre– hydrostatic scaleshydrostatic scales

Liquids:volumetric flask– volumetric flask

– pipetteb tt– burette

DensityBulk density Density(specific gravity)X

m =

V

[ kg.m-3 ]

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DensityBulk density Density(specific gravity)

m =

m =v =

Vh + Vp

= Vhp

m mass of material m mass of materialm… mass of materialVh… volume of solid

material

m… mass of material

Vh volume of solidmaterialVp… volume of voids

i i l

Vh… volume of solid material

pin material

Bulk density x Density

v = 500 kg.m-3 v = 2400 kg.m-3

2400 k 3 = 2500 kg m-3 = 2400 kg.m-3 = 2500 kg.m-3

AAC tAAC(aerated autoclaved concrete)

concrete

Bulk density determinationBulk density determinationmm

v = V + V

• mass m by weighing

Vh + Vp

• mass m by weighing• volume (Vh+Vp)h p

– counting from sizes (regular shape)shape)

– in graduated cylinderb h d t ti l b l– by hydrostatical balance

By graduated cylinderBy graduated cylinderm

ABm

vρ

BB

mρ C

water

1

ρm)(mAB

vρ

m m

Awaterρ

(m )Cm)(mAB

mvρ 1 m (m1)

ρwater

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Hydrostatical balanceHydrostatical balance

• irregular shape – volume?

Hydrostatical balanceArchimedes principle:

Hydrostatical balancep p

„Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of theby a force equal to the weight of the fluid displaced by the object.“

mass of material, weighted under water is lower than that weighted in the air From thatlower than that weighted in the air. From that difference the volume of the displaced water can be count (its density is known). m( y )

Vm

OH2

volume of displaced water = volume of material

Wire basket methodWire basket method EN 1097 6• EN 1097-6

[M 3]M [Mg.m-3]1Mg.m-3 =1000kg.m-3)MM(M

M321

4Wa

)( 321

M1 mass of the wet sample, dryed on the surface (g)M2 mass of the sample in the basket under water (g)2

M3 mass of the empty basket under water (g)M4 mass of dry sample (g)4 y p (g)w water density at testing temperature (Mg.m-3)

Bulk density of building materialsBulk density of building materials

kg.m-3

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Specific gravity (density)determination

mv =v

Vh

• Mass m by weighing

• Volume Vh by pycnometerVolume Vh by pycnometer– material have to be grounded !

PycnometerPycnometer• (glass) bottle with a close fitting stopper with• (glass) bottle with a close-fitting stopper with

a capillary tube through it allowing excessliquid to escapeliquid to escape

• the volume of the liquid in the pycnometer isl thalways the same

• allows repeated obtaining a given volume ofliquid with a high accuracy

Determination of density byDetermination of density by pycnometric method

m1 m2 m3 m4

)(34

k12

mm)m(mρ)-m(m ρ

3412 mm)m(m

Helium pycnometerHelium pycnometer• the size of helium atoms is very small• helium, under precisely-known pressure, is , p y p ,

used to fill small voids within a specimen • the volume change of helium in a constant• the volume change of helium in a constant

volume chamber allows determination of solid volumevolume

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Density of building materialsDensity of building materials

kg.m-3

PorosityPorosity

• ratio of the volume of the voids to the total volume of the material

︶. ︵VVp vh 10011

• usually expressed as a percentageusually expressed as a percentage

Types of poresTypes of poresl d• closed • open

p = pclosed + popen

P ti l t d t itProperties related to porosity

• Water absorption → frost resistancep

• Gas and liquid transport

• Acoustic absorptivity

• Thermal conductivity

M h i l i h• Mechanical properties - strength

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Pore size distributionPore size distributionMercury porosimetryy p y• the intrusion of a mercury at high

pressure into a pores• the pressure needed to fill the pores

increases with decreasing pore didiameters

• 400 MPa Ø1,5 nm1000.7

60

70

80

90

0.4

0.5

0.6

d)e/cm

3 g-

1

20

30

40

50

0.2

0.3

0.4

dV/d

(log

mul

ativ

e po

re v

olum

e

0

10

20

0

0.1

0.001 0.010 0.100 1.000 10.000 100.000

Cum

Pore diameter/mm

Properties of bulk materialsProperties of bulk materialsBulk material = solid material dividedBulk material = solid material divided

into many small particles • an assembly of solid particles that is large

enough for the statistical mean of any property to be independent of the number of particles

Void ratioVoid ratio

• ratio between the total volume and the volume occupied only by the particles p y y p

• the amount of void space is a function of the gradation particle shape andof the gradation, particle shape and texture, and the amount of compaction of the material

CompactingCompacting

Uncompacted voids - Compacted voids -pthe amount of void space present when the

pthe amount of void space present when the

material is in an uncompacted, unconsolidated state

material is in an maximally compacted, stateunconsolidated state. state.

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Loose bulk densityLoose bulk densitym

mph VVVm

smph VVV

• in the uncompacted state

• in the consolidated state (compacted)

Loose bulk density determination

• Standard container (volume according maximum particle size) + tamping rod

Procedure:• Loose weight:g

– fill the container– struck off the surplusstruck off the surplus

• Compact weight:– fill the container in equal layersfill the container in equal layers – each layer being subjected to

strokes with the tamping rodp g– struck off the surplus

AggregatesAggregates

• granular material used in construction

• inorganic rocklike material• inorganic rocklike material

• various sizes and shapesvarious sizes and shapes

• particle size < 125 mmp

Size gradationSize, gradationGradation = the particle size distributionGradation = the particle size distribution• Amount of various particle sizes present

in an aggregatedetermined by sieve analysis– determined by sieve analysis

– expressed as the percentage p p gby mass passing a specified set of sieves

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Standard sieves (EN 933-2)Standard sieves (EN 933 2) 125 mm63 mm

31,5 mm16 mm8 mm4 mm 2 mm1mm

0,500 mm0250 mm0,125 mm0,063 mm

Type of aggregates according sizeType of aggregates according size

125stone

12563

31 5 coarse (gravel)31,5168

coarse (gravel)

ll i842

all-in aggregate aggregate

10,5

0,250,125

fine (sand)

0,0630 fines

Sieve analysis (EN 933 1)Sieve analysis (EN 933-1)

di iding p a material into si e• dividing up a material into size fractions by passing it through sieves with decreasing apertures

Aggregate size (fraction)Aggregate size (fraction)d i ti f t i t• designation of aggregate in termsof lower (d) and upper (D) sievesizes expressed as d/D*– 16/64 aggregate will be that aggregate16/64 aggregate will be that aggregate

which passes the 64 mm sieve and isretained on the 16 mm sieve

* this designation accepts the presence ofthis designation accepts the presence ofsome particles which are retained on theupper sieve (oversize) and some which passpp ( ) pthe lower sieve (undersize)

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Sieve analysis - definitions• Individual retained – the mass or

Sieve analysis - definitions

percentage retained on one sieve after test• Cumulative retainedCumulative retained

– sum of the mass or percentages retained onpercentages retained on the sieve and on all coarser sievescoarser sieves

• Cumulative passing – sum of the mass or percentage passing– sum of the mass or percentage passing the sieve (e.g. sum of the retained on all finer sieves and pan)finer sieves and pan)

Particle size distribution curveParticle size distribution curve

hi l li ti f 100

9585

70

80

90

100

ive

pass

ing

[%]• graphical listing of

the amount of ti l di 60

40

50

60

70

cum

ulatparticles according

to particle size 20

101050

0

10

20

30

64321684210 50

ranges

64321684210.50

sieve size [mm]• continuous line– axe X – sieve size (particle size)(p )– axe Y – cumulative passing (percent passing

by weight)

Example:pAggregate with the size 4/16 - 1000 g

Aft i l i th t i d• After sieve analysis these retained wereobtained:

Sieve aperture size

Individual retained

g %

Cumulative retained Cumul. passing

% %64 0 032 50 516 100 10

0 1005 95

15 8516 100 108 250 254 400 40

15 8540 6080 2000 0

2 100 101 0 0

80 090 1090 10

0,5 50 5 0,5 (pan) 50 5

95 5100 0

Particle size distribution curve100

9590

100

sing

[%]

40 % ti l 85

70

80

ativ

e pa

ss

•40 % particles bigger than

8 mm60

50

60

Cum

ula 8 mm

30

4060 % particles smaller than

fraction 1/2 omitted (gap grading)

20

101050

10

20smaller than

8 mm5

064321684210.50

Particle size [mm]• only rising (decreasing) character Particle size [mm]only rising (decreasing) character• missing fraction – horizontal line• vertical line – never!

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Particle size distribution curve45

Particle size distribution curve

35

40

45

25

30

35

15

20

25

5

10

064321684210,50

Fineness modulusFineness modulus• to determining the degree of uniformity of the• to determining the degree of uniformity of the

aggregate gradationsingle number• single number

• obtained by adding the total percentages of i l i l h hmaterial in a sample that are coarser than

each of a specified series of sieves ( l i i d) d(cumulative percentages retained) and dividing the sum by 100.

% sieves specified on retained cumulativeFM% 100

FM

%100

% sieves specified on retained cumulative FM

Z16

% 100

Z16

Z

16+

Z16 + Z8

Z4

Z816 8

+Z16 + Z8 + Z4Z4

Z2

+Z16 + Z8 + Z4 + Z2

Z1

+Z16 + Z8 + Z4 + Z2 + Z1

+Z0,5

+Z16 + Z8 + Z4 + Z2 + Z1 + Z0,5

+Z0

+Z16 + Z8 + Z4 + Z2 + Z1 + Z0,5 + Z0

Fineness modulusEN 12620

Specified sieves: (4 2 1; 0,5 0,25 0,125)

0,125)] ( 0,25) ( 0,5) ( 1) ( 2) ( 4) [(FM

100

FM

1 FM 6

• the bigger FM is, the coarser is aggregategg , gg g

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FinesFines

ti l i f ti hi h th 0 063= particle size fraction which passes the 0,063 mm sieve

l th d f d t i i ( hi- several methods for determining (washing, sand equivalent test, methylene blue test, air jet sieving)jet sieving)

- maximum value: fi t 3 %- fine aggregate 3 %

- coarse aggregate 1,5 %higher content of fines:- higher content of fines: - higher consumption of cement

lower strength- lower strength

Shape of particlesShape of particlesParticles:a c es• shape – rounded, angular, elongated,

flatflat

• surface – smooth, abraded (rough)

Flakiness indexFlakiness index (EN 933-3)

• particles are flakey when their thickness is less than 0 6 ofthickness is less than 0.6 of their mean size

i l i ith l t d• special sieves with elongated apertures

• the flakiness index - the weight of the flakey aggregate as a percentage of the aggregate tested

Shape indexShape index(EN 933-4)

• a ratio between the weight of particles with L/E > 3 and weight of all measured particlesL/E > 3 and weight of all measured particles in percents.

shape ratio L/E the length L and the– shape ratio L/E – the length L and thethickness E of each particle

– L/E 3 – non-cubic particles

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Shape ratio L/EShape ratio L/E

LE

L

Specific surfaceSpecific surface

• finenesst t l f it f• total surface area per unit of mass

• units: m2/ kg (cm2/g)units: m / kg (cm /g)

• the higher the specific surface is, the finer t i l ill bmaterial will be

Specific surface2 cm

Specific surface8 cm

2 cm

8 cm

8 cm

a) Surface b) Surface

8 cm

a) Surface6 x 8 x 8 cm =

384 cm2

b) Surface64 x (6 x 2 x 2) =

1536 cm2384 cm2 1536 cm2

1/4 S 4 Sab = 1/4 aa Sb = 4 Sa

Specific surface of some materials

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S ifi f d t i tiSpecific surface determination

• sieving

• gas permeability• gas permeability

• adsorption

Air permeability methodAir permeability method

Coarse material Fine material

• the specific surface is derived from the resistance to flow of air through a porous bed of the powder

Blain apparatusBlain apparatus Blain apparatusBlain apparatus

STARTSTART

STOP

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Specific surface calculationSpecific surface calculation

teKS3

1,0)e1(

S

K t t t• K apparatus constant • e porosity of the bed (usually e = 0,500)• t measured time s• cement density g.cm-3• air viscosity at the test temperature [Pa.s]

Apparatus calibrationApparatus calibration• apparatus must be calibrated using a known• apparatus must be calibrated, using a known standard material

000

1,0)e1(SK

0300

teS K

• S0 specific surface of the reference cement cm2.g-1• 0 density of the reference cement g.cm-30 y g • t0 measured time s• 0 air viscosity at the test temperature Pa.s0 a scos ty at t e test te pe atu e a s

Fineness of grindingFineness of grinding• cements and similar materials• cements and similar materials• described by the specific surface• finer cement offers a greater surface area for

hydration and hence faster the development of strength

• specific surface of common cements:p

250 – 350 m2/ kg (2500 - 3500 cm2/g)

Mechanical propertiesMechanical propertiesp pp p

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Solid materials

• structural rigidity • resistance to changes of shape or volume • atoms are tightly bound to each other g y

Atomic vibration in crystalline solidcrystalline solid

Mechanical propertiesMechanical propertiesd ib t i l' b h i h f i• describe a material's behavior when force is applied

• describe characteristics such as their strength and resistance to deformation

Mechanical propertiesMechanical propertiesd f ti ti (b f d t ti )• deformation properties (before destruction)

• strength properties (at the moment of break)

Type of loadingType of loading

compression bending shearcompressiontension

bendingtorsion

shear

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Force x StressForce x Stress• stress is a measure of the internal forces• stress is a measure of the internal forces

which are a reaction to external forces

Force F stress

[N] [Pa][ ] [ ]

Isaac Newton Blaise Pascal

Compressive stressCompressive stress

FSF

S

005,0 x 005,0S 2m 000025,0

Units of stressUnits of stressSI units: Pascal

N N2

m

NPa 2

mm

NMPa

Imperial units: pound-force per square inch

lbfpsi ksi = 1000 psi2inpsi ksi 1000 . psi

1 psi = 6 894,76 Pa

Strength propertiesg p p

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StrengthStrengthabilit to ithstand an applied load• ability to withstand an applied load without failure

• the maximum stress sustained by a material loaded to failurematerial loaded to failure

StrengthStrength

According the way of obtaining:g y g

– theoretical (structural)– technical– statistical– statistical

Theoretical strengthTheoretical strength• Counted from the number and strength of• Counted from the number and strength of

the bonds between atomsXX • defects in the crystal lattice – real strength is

distinctively lower (ca 1000x)

T h i l t thTechnical strength• from the testing of the real material

samplesample

– material have to be homogenous– test samples in the appropriate– test samples in the appropriate

shape (cylinder strength, cubic t th )strength...)

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Test samplesTest samples• shaping from the materialshaping from the material

– cutting, carving, drilling• directly made in the required shape

– cubes, cylinders.., y• whole products

b i k bl k– bricks, blocks

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