Building MaterialsBuilding MaterialsBuilding MaterialsBuilding Materials

Lecture 6Lecture 6

BindersBinders

BindersBinders• materials, that binds other materials together

processing setting hardening(phase change) (increase of

0 21

0 mixing water and

(phase change) (increase of strength)

0 ..... mixing water andbinder

1 ..... initial setting time2 ..... final setting time

BindersBinders• in the building industry mostly inorganicin the building industry mostly inorganic

H d liNon-hydraulic• need air to set

Hydraulic• can set and• need air to set can set and

harden in water• water resistant• water resistant

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Hydraulic bindersHydraulic binders• binders which set and harden as a result• binders which set and harden as a result

of chemical reactions with water and continue to harden even if subsequentlycontinue to harden even if subsequently placed under water f thi t f h d lit i• for this to presence of hydraulites is necessary: (SiO2, Al2O3, Fe2O3)

Non-hydraulic binders:• gypsum

Hydraulic binders:• hydraulic limegyp

• lime• magnesia binder

hydraulic lime• cement

g• water glass • geopolymers

Hydraulic modulusHydraulic modulus

CaOHM 32322 OFeOAlSiO

HM

• non-hydraulic lime HM 6• hydraulic lime HM < 6• portland cement HM < 2 5• portland cement HM < 2,5• high alumina cement HM < 1,5

Hydraulic bindersHydraulic binders Hydraulic binders• opus caementicium

Hydraulic binders• opus caementicium

"There is also a kind of powder f hi h t lfrom which natural causes produces astonishing results. Thi b t h i dThis substance, when mixed with lime and rubble, not only l d t th t b ildi flends strength to buildings of other kinds, but even when

i t t d f it ipiers are constructed of it in the sea, they set hard under

t "water."Marcus Vitruvius Pollio, 13 B.C.

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CementCementCementCement

Joseph Aspdin

1824 - patent for„Portland cement“„Portland cement

Cement manufactureCement manufactureR t i lRaw material:• minerals with CaCO3 + SiO2

– impure limestone, marl, chalk

secondary raw mat• secondary raw mat.– clay, shale, fly ash,

slag• calcium sulphate

– gypsum, anhydrite

Cement manufacture

>1400°C

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SinteringSintering lid ti f d ti l b h ti• consolidation of powder particles by heating

at 1300 - 1400°C clinkerth t ti l diff t th i hb i– the separate particles diffuse to the neighboring powder particles

– chemical reactions formation of cement compounds – clinker minerals(calcium silicates)

Rotary kilnRotary kiln

about 1480 °C

Chemical composition of cementChemical composition of cement

• Ca 46 4 % • CaO 65 %Ca 46,4 %• Si 9,8 %

• CaO 65 %• SiO2 21 %

• Al 3,2 %• Fe 2,1 %

• Al2O3 6 %• Fe O 3 %,

• Mg 1,2 %S 1 0 %

• Fe2O3 3 %• MgO 2 %

• S 1,0 %• O 35,3 % • SO3 2 %

Σ 99 0 %• Σ 99,0 % • Σ 99,0 %

• determined by chemical analysis (EN 196-2)

Main clinker mineralsMain clinker minerals

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Cement notationCement notation

• an abbreviated record of the oxides

Calcium oxide (lime) C CaO

Silicon dioxide (silica) S SiO2

Aluminum oxide (alumina) A Al2O3

Iron oxide F Fe2O3

Minerals in notationMinerals in notation

Tricalcium silicate C3S 3CaOSiO2Tricalcium silicate C3S 3CaO SiO2

C SDicalcium silicate C2S 2CaOSiO2

Tricalcium aluminate C3A 3CaOAl2O3

Tetracalciumaluminoferrite C4AF 4CaOAl2O3

Fe Oaluminoferrite 4 Fe2O3

Cement minerals propertiesC3S

- hydrates and hardens rapidly - responsible for initial set and early strength

C2S- hydrates and hardens slowly - responsible for later strength increase - low hydration heat

C3A- hydrates and hardens the quickest- a large amount of heat - important in sulphate corrosion of concrete

C4AF- contributes little to strength- color effects

Composition of Portland cement

C AF

gypsum(3,5 %)

other (1,5 %)C4AF

(8%)

(3,5 %) (1,5 %)

C3A (12%) C S( 12%) C3S

(50 %)

C2S( 25%)(25%)

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Composition of different cements

Comp.Cement type

C3S C2S C3A C4AFCement type

Portland cement 65 15 8 9

C. with low heat of h d ti 25 55 3 14hydration 25 55 3 14

Sulphate resistant c. 73 9 2 13Sulphate resistant c. 73 9 2 13

White cement 73 14 11 0

Cement compound pcomposition determination

• microscopet diff ti• roentgen diffraction

• Bogue calculationg

Bogue calculationBogue calculation d t i th i t ti f• determines the approximate proportions of the four main minerals in Portland cement li kclinker

• the calculation assumes that the four main clinker minerals are pure minerals

• there is necessary to know chemical ycomposition of cement (% amount of oxides)

• refers to cement clinker, but it can be adjusted for use with cementadjusted for use with cement

Bogue calculation principlesBogue calculation principles1. Ferrite is the only mineral to contain iron. Assume

th t ll th F O i i C AFthat all the Fe2O3 is in C4AF2. The aluminate content is fixed by the total alumina

content minus the alumina in the ferrite This cancontent minus the alumina in the ferrite. This can now be calculated, since the amount of ferrite has been calculated.been calculated.

3. Deduct from the CaO content the amounts attributable to C4AF, C3A and free lime, and solve 4 , 3 ,two simultaneous equations to obtain the contents of C3S and C2S.

C3A 3CaOAl2O3

C4AF 4CaOAl2O3 Fe2O3

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Bogue calculationBogue calculation

[C AF] = 3 04*[F][C4AF] = 3.04 [F][C3A] = 2.65*[A] - 1.69*[F][C3S] = 4.07*[C] - 1.43*[F] - 6.72*[A] - 7.60*[S][C S] = 8 6*[S] 3 07*[C] + 1 08*[F] + 5 1*[A][C2S] = 8.6*[S] - 3.07*[C] + 1.08*[F] + 5.1*[A]

• where the [F] [C] [A] [S] are the weightwhere the [F], [C], [A], [S] are the weight percentages of the oxides F2O3, CaO, Al2O3, SiO2 in the clinkerSiO2 in the clinker

Cement hydrationCement hydrationi f i ibl h i l ti• series of irreversible chemical reactions

between cement and water. d i h d ti th t t d• during hydration the cement sets and hardens, “gluing” the aggregate together in a solid masssolid mass

Hydration depends on:• cement type (chemical composition)• fineness• amount of water added• presence of other admixturespresence of other admixtures

Cement hydrationCement hydrationStage1: mixing (< 15 minutes)• aluminate reacts with water and

sulfate, forming a gel-like material (C-A-S-H)• this reaction releases heatthis reaction releases heat• the C-A-S-H gel builds up around the grains,

limiting water’s accesslimiting water’s access to the grains and thuscontrolling the rate ofcontrolling the rate ofaluminate reaction

Cement hydrationCement hydrationStage 2: Dormancy (2 - 4 hours)• the C-A-S-H gel is controlling aluminateg g

reactions• little physical change occurs in the concretelittle physical change occurs in the concrete• silicates ([C3S] and [C2S]) slowly dissolve,

calcium ions and hydroxylcalcium ions and hydroxyl(OH) ions accumulate in solutionsolution

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Cement hydrationCement hydrationStage 3: Setting (2 - 4 hours)Stage 3: Setting (2 - 4 hours)• the solution becomes super-saturated with

calcium ions (from dissolving alite primarily)calcium ions (from dissolving alite primarily)• fiber-like C-S-H and crystalline CH start to

fform• meshing of C-S-H with other solids causes

the mixture to stiffen and set• aluminate and sulfate

continue to react, and needle-like ettringite crystals g yform

Cement hydrationCement hydrationStage 4 : Cooling (several hours)• the concrete is gaining strength, as the g g g

amount of C-S-H (and CH) increases. • sulfate, which has continued reacting withsulfate, which has continued reacting with

aluminate will be depleted. • any remaining aluminate• any remaining aluminate

now reacts with ettringite to form monosulfate (whichform monosulfate (whichdoes not significantly affect concrete properties)concrete properties)

Cement hydrationCement hydrationStage 5: Densification (years)Stage 5 e s cat o (yea s)• belite reactions start to have an impact

belite reactions also produce C S H and CH• belite reactions also produce C-S-H and CH, forming a solid mass

• the longer the cement hydrates – the greater the concrete’s strength– the lower its porosity

Cement settingCement setting

0 min

15 min

30 min30 min

55 min

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Cement hydrationCement hydration Cement types ypEN 197-1: 5 main types - 27 common cements•• CEM ICEM I - Portland cement

– min 95% of clinker•• CEM IICEM II - Portland composite cement

– up to 35% of siliceous fly ashup to 35% of siliceous fly ash •• CEM IIICEM III - Blastfurnace cement

– up to 95% blastfurnace slagup to 95% blastfurnace slag •• CEM IVCEM IV-- Pozzolanic cement

– up to 55% of pozzolana– up to 55% of pozzolana•• CEM VCEM V - Composite cement

up to 80% of blastfurnace slag or fly ash– up to 80% of blastfurnace slag or fly ash and pozzolana

Cement constituentsCement constituents

• Portland cement clinker (K) – made by sintering a mixture of raw y g

materials• Granulated blastfurnace slag (S)• Granulated blastfurnace slag (S)

– made by rapid cooling of a slag, as bt i d b lti i iobtained by smelting iron ore in a

blastfurnace– possesses hydraulic properties when

suitably activated

Cement constituentsCement constituents

Pozzolanic materials – natural substances of siliceous or silico-

aluminous composition – when finely ground and in the presence ofwhen finely ground and in the presence of

water, they react with dissolved calcium hydroxide Ca(OH)2hydroxide Ca(OH)2

• Natural pozzolana (volcanic origin) (P)• Natural calcined pozzolana (Q)

– activated by thermal treatmentactivated by thermal treatment

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Cement constituentsCement constituentsFly ashesFly ashes

– obtained by electrostatic or mechanical precipitation of dust-like particles from flueprecipitation of dust-like particles from flue gases from furnaces fired with pulverised coalcoal

• Siliceous fly ash (V)• Calcareous fly ash (W)

Cement constituentsCement constituents

• Burnt shale (T) – specifically burnt oil shale at approximately p y pp y

800 °C• Limestone (L LL)• Limestone (L, LL)

– CaCO3 content ≥ 75 % by mass• Silica fume (D)

– originates from the reduction of high purityoriginates from the reduction of high purity quartz with coal in electric arc furnaces in the production of silicon and ferrosiliconthe production of silicon and ferrosilicon alloys (very fine spherical particles)

Cement classification(EN 197-1)

CEM I 42,5 R

type

strength class

high earlyg ystrength

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Strength classes of cementStrength classes of cementth t d d t th f t i• the standard strength of a cement is the compressive strength in MPa determined in accordance with EN 196-1 at 28 daysy

• three classes of standard strength:32 5• 32,5

• 42,542,5• 52,5

Strength increaseStrength increase

R [MPa]

CEM II 42,520 5C

42,5 CEM I 42,5 R5C5 C

CEM II 42,5

T [days]28

Properties of cement typesp yp• Portland cement

• high strengthhigh strength• fast increase of strength• big amount of hydration heatbig amount of hydration heat

• Portland slag, blastfurnace cement• high sulphate resistance• high sulphate resistance• low hydration heat

• silica fume cement• silica-fume cement • low porosity of concrete• exceptionally high strength• exceptionally high strength

• fly-ash cementgood workability• good workability,

• lower concrete water content

Use of Portland cementUse of Portland cementconcretes ith high strength• concretes with high strength

• reinforced and prestressed concretep• demanding precast products

t ti d t f t d• constructions exposed to frost and deicing admixtures (air-entrained concretes)

• sprayed concrete• sprayed concrete(shotcrete)

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Use of Portland composite cement

• common concretes, esp. ready-mixed• common reinforced concrete

construction• massive concrete constructions

(supporting walls waterworks)(supporting walls, waterworks) • not suitable in chemically aggressive

environment and for frost-resisting constructions

Use of other cementsUse of other cements

Blastfurnace cements:• water resisting constructions• water-resisting constructions• massive constructions

Composite cements:Composite cements:• massive construction, fundaments eg.g• less demanding precast products

Special cementsSpecial cements• expansive cement – against dryingexpansive cement against drying

shrinkage• fast repair cementfast repair cement• sulphate resistant - C3A < 3,5%• white Fe < 1%• white - Fe < 1%• colored – 5-10 % of pigments

t ti d b i t• strontium and barium cements– Ba or Sr instead of Ca– high resistance to attack by sea water, – resistance to high temperatures– radiation shields

Masonry cement (MC)Masonry cement (MC)EN 413 1EN 413-1• for use in mortars for masonry

t ticonstruction• lower strength

MC5, MC 12,5, MC 22,5• can contain besides the portland

cement lime claycement lime, clay

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Calcium aluminate cement (High-alumina cement)

• consisting predominantly of hydrauliccalcium aluminates

• over 35 % of Al2O3• ultra - rapid strength development• high chemical resistance• refractory material (to 1750C)y ( )• But!• loss of strength due to „conversion“loss of strength due to „conversion• several failures in the 1970s→ forbidden for the use in the bearing→ forbidden for the use in the bearing

constructions !

Cement testingCement testingEN 196 – Methods of testing cementg– 1 Determination of strength– 2 Chemical analysis of cement y– 3 Determination of setting time and soundness – 4 Quantitative determination of constituents – 5 Pozzolanicity test for pozzolanic cement – 6 Determination of fineness– 7 Methods of taking and preparing samples of

cement – 10 Determination of the water soluble chromium

(VI) content of cement– 21 Determination of the chloride, carbon dioxide

and alkali content of cement

Testing of cements - termsTesting of cements - terms• cement paste: cement + watercement paste: cement water• cement mortar: cement + water +

fine aggregatesfine aggregates• concrete: cement + water + fine +

tcoarse aggregates• water/cement ratio w/c : mass

of water/mass of cement

• paste with standard (normal) consistence(normal) consistence

Determination of strength(EN196-1)

iflexural

compressive

M

(bending)

WMRy

max

MR maxFR maxW

Ry ARt

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Expression of test results ofExpression of test results of compressive strength

• test set - 3 prism → 6 halves

• arithmetic mean of the 6 individual result• if one result within the 6 individual resultsif one result within the 6 individual results

varies by more than ± 10 % from the mean, discard this result and calculate thediscard this result and calculate thearithmetic mean of the 5 remaining results

• if one result within the 5 remaining results• if one result within the 5 remaining results varies by more than ± 10 % from their mean, discard the set of results and repeat thediscard the set of results and repeat the determination

Chemical analysis of cement(EN196-2)

l i i i• loss on ignition• residue insolubleresidue insoluble• determination of sulfate

d t i ti f j l tdetermination of major elements– silica– oxides Fe, Al, Ca, Mg– chloridechloride– carbon dioxide

lk li– alkali

Setting time (EN196 3)Setting time (EN196-3)

Louis Vicat(1786 -1861)

Soundness (EN196 3)Soundness (EN196-3)

• the ability of a hardened cement paste to• the ability of a hardened cement paste to retain its volume after setting without delayed destructive expansion caused by CaO ordestructive expansion caused by CaO orMgO

H L i L Ch t liHenry Louis Le Chatelier(1850-1936)

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Quantitative determination of constituents (EN196-4)

• Portland cement clinker• blastfurnace slag• siliceous fly ash• siliceous fly ash• natural pozzolans• limestone

ili f• silica fume • set regulatorsg

Pozzolanicity (EN196 5)Pozzolanicity (EN196-5)• comparing the concentration of calcium ion, p g

expressed as CaO, present in the aqueous solution in contact with the hydrated cement, yafter a fixed period of time, with the quantity of calcium ion capable of saturating a solution of p gthe same alkalinity

n

failum io

n nt

ratio

nm

ol/I]

passCal

ciu

conc

e[m

m

Hydroxyl ion concentration [mmol/I]

Finneness (EN196 6)Finneness (EN196-6)

• Blaine apparatus

teKS3

1,0)e1(

S

Taking and preparing samplesTaking and preparing samples (EN196-7)

• from bags, containers, bulk silos filling machinesbulk, silos, filling machines

• quartering, sampling tube, screw sampler

Water soluble chromium (VI) content (EN196-10)content (EN196 10)

• hygienic and ecological properties• hygienic and ecological properties

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M h i l d h i lMechanical and physicalrequirements (EN197 1)requirements (EN197-1)

Strength class

Compressive strength MPa Initialsetting

time

Soundness(expansion)Early strength Standard strength

2 days 7 days minut mm32,5 N - ≥ 16,0

class time ( p )Early strength Standard strength

28 days32,5 N ≥ 16,032,5 R ≥ 10,0 -42,5 N ≥ 10,0 -

≥ 75

≥ 60 ≤ 10

≥ 32,5

≥ 42 5

≤ 52,5

≤ 62 542,5 R ≥ 20,0 -52,5 N ≥ 20,0 -52 5 R ≥ 30 0 -

≥ 60

≥ 45

≤ 10≥ 42,5

≥ 52,5

≤ 62,5

-52,5 R ≥ 30,0

Hydraulic limeHydraulic lime• the Romans (100 B C )• the Romans (100 B.C.)

– (Plinus, Vitruvius) „Opus caementicium“

• forgotten in the middle age• forgotten in the middle age• discovered again in the 18th

century by burning limestone containing clays

Eddystone Lighthouse• 1756 – John Smeaton• 1796 roman cement“

Eddystone Lighthouse

(James Parker)• 1796 - „roman cement• Louis Joseph Vicat

(James Parker)

Hydraulic limeHydraulic limeRaw material:Raw material:• argillaceaous (clayey) limestones → NHL

i k li (b d li t ) l i• quick lime (burned limestone) + pozzolanicmaterials → HL

Pozzolanic materials (pozzolans):consist mainly from reactive silica (SiO ) and– consist mainly from reactive silica (SiO2) and alumina (Al2O3)

– when finely ground and in the presence of water, y g p ,they react with dissolved Ca(OH)2

– volcanic ash, fly ash, silica fume, high-reactivity t k li d l t d bl t f lmetakaolin, ground granulated blast furnace slag

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H d li li f tHydraulic lime manufacture

Natural hydraulic lime (NHL):burning of raw materials at the• burning of raw materials at the temperature under 1250 °C

( )• slaking (only when HM > 3)

Hydraulic lime (HL):• grinding of quicklime together• grinding of quicklime together

with pozollans

Hydraulic limeHydraulic limei t t t tl d t h hi h• in contrast to portland cement has higher amount of the free CaO and no alite (C3S)

According the degree of hydraulicity (hydraulic d l )modulus):

• feebly hydraulic lime (HM 6 - 9) - need l kislaking

• moderately hydraulic lime (HM 3 - 6) – need l kislaking

• eminently hydraulic lime (HM 1,7 - 3) – does t d l kinot need slaking

Natural hydraulic lime - EN 459Natural hydraulic lime EN 459

SO Free limeStrength

Type SO3 (mass %)

Free lime(mass %) after 28 days

[MPa]

NHL 1 2 ≥ 50 ≥ 0,5 - 3

NHL 2 2 ≥ 40 ≥ 2 - 7

NHL 3,5 2 ≥ 25 ≥ 3,5 - 10

NHL 5 2 ≥ 15 ≥ 5 - 15

Hydraulic lime useHydraulic lime use

• monuments renovationsbetter breathing of walls– better breathing of walls

– moisture can evaporate – mortars and renders do not set too hard – expansion joints can p j

often be avoided – reduced condensationreduced condensation – no salt staining

Using of cement with old bricks

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Non-hydraulic bindersNon-hydraulic binders

gypsum• gypsum• (non-hydraulic) lime• anhydrite• water glassg• magnesium binder

Calcium sulphate bindersCalcium sulphate binderst i l i l h t (C SO )• contain calcium sulphate (CaSO4)

– plaster of Paris (calcined gypsum)– anhydrite binder

• from gypsum rock - CaSO4 2H2OCaSO4 2H2O

• natural anhydrite- CaSO- CaSO4

Naica mine, Mexiko

Gypsum sourcesGypsum sourcest l k• natural rock

• FGD gypsum gy– synthetic product from flue

gas desulfurization systems at electric power plants

• phosphogypsump p gyp– by-product of processing

phosphate ore into fertilizer with lf i idsulfuric acid

• citrogypsum• titanogypsum

Plaster of Paris (gypsum)Plaster of Paris (gypsum)

• calcium sulphate hemihydrateCaSO4 · 0,5H2O

• one of the oldest binders– Anatolia and Syria – 5000 b.C.– Egyptians– Greeks– Romans

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Plaster of Paris manufacturePlaster of Paris manufacture

l i ti (150 200°C)• calcination (150 - 200°C)

CaSO · 2H O + heat → CaSO · 0 5H OCaSO4 · 2H2O + heat → CaSO4 · 0,5H2O +1,5H2O

Gypsum dehydrationGypsum dehydration

Difference between a Difference between a plasters

- plaster - plasterParticle size 1 – 5 m 10 – 20 mParticle porosity high lowp y gSpecific surface big smallStrength increase fast slowerStrength increase fast slowerFinal strength lower higher

Gypsum setting and hardeningGypsum setting and hardening

CaSO4·0,5H2O + 1,5H2O → CaSO4·2H2OInitial setting:

• due to a colloidal mechanism or action of• due to a colloidal mechanism or action of capillary forces causing a packing together of hemi-hydrate particleshemi-hydrate particles

Hardening and final setting

• a crystallization process

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EN 13 279 - Gypsum binders and gypsum plasters. Definitions and

requirementsrequirements

Gypsum properties modificationGypsum properties modification• setting retarders (citric acid, molasses, g (

blood, saliva, agar)• setting accelerators (hardened gypsum -setting accelerators (hardened gypsum

dihydrate)fungicides• fungicides

• hydrophobic additives• pigments• plasticizers (Althaea officinalis -p ast c e s ( t aea o c a s

Marshmallow root)• reinforcement (glass fibersreinforcement (glass fibers,

animal hairs)

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