BuildingBuilding materialsmaterialsBuildingBuilding materialsmaterials

Lecture 7Lecture 7

Non-hydraulic binderspart II

calcium sulphate binders: calcium sulphate binders: gypsum anhydrite

(non-hydraulic) lime(non hydraulic) lime water glass magnesium binder magnesium binder

Strength of gypsumStrength of gypsum moisture content

with increasing moisture the strength decreases

water/gypsum ratio with increasing w/g the strength decreases with increasing w/g the strength decreases

Bulk density Compressive t thConditioningMoisture in

gypsumCompressive

strengthw/g

Bulk density strength

kg.m-3 MPa

0 50 1410 14 6

Conditioning gyp g% MPa %

Dried at 35 -40 C 0 13,8 100

0,50 1410 14,6

0,55 1300 13,0

0,60 1230 11,4

In air with 65 % RH 0,04 13,6 98,5

In air with 90 % 0,15 12,9 93,5

0,65 1170 10,8

0,75 1040 9,5

% RH 0,15 12,9 93,5

Immersed in water 17,50 6,4 46,5

Gypsum fire resistanceGypsum fire resistancefl bl ( l A1) non flammable (class A1)

contains water of crystallization (17 % of its weight)d t th fi th h i ll bi d t i exposed to the fire, the chemically combined water is

released in the form of water vapor the dehydration (calcination) of gypsum occursy ( ) gyp

calcined gypsum adheres to the uncalcined material and retards the calcination process

until all the water of crystallization has been liberated, the temperature on the unexposed side will not exceed 100Cexceed 100 C

the gypsum can serve as a fire retardant with ability to delay the spread of fire up to 4 hours with ability to delay the spread of fire up to 4 hours protection of wood and steel elements against fire

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Gypsum after fire test (Mokrsko)Gypsum after fire test (Mokrsko) Gypsum useGypsum use plasters in interior plasters in interior blocks floor screeds gypsum boards (drywall)gyp ( y ) gypsum fiberboards

Lime - gypsum plasterLime - gypsum plaster gypsum sets quickly, lime is slow to set

combination of lime and gypsum plasters sets at a medium speed

while setting, gypsum plaster expands slightly g gy g yand lime contracts slightly the plaster does not crack

better workability

Gypsum board (drywall)Gypsum board (drywall) panel made of a paper liner wrapped around

an inner core made from gypsum with fibers (cellulose and/or fiberglass)

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Gypsum board typesGypsum board types Gypsum plasterboard - type A G. p. with control density - D Gypsum sheathing board - E

i t l ll d d t b ti in external walls. reduced water absorption rate with a minimum water vapor permeability

G. p. with improved core adhesionG. p. with improved core adhesion at high temperatures - F mineral fibers and / or other additives in the

gypsum coregypsum core G. p. with reduced water absorption

rate - H1 H3 G. p. with enhanced surface hardness - I G. baseboard - P

G i h h d h R G. p. with enhanced strength - R

Special gypsum boardsSpecial gypsum boards fire proof (F) fire proof (F)

glass fibre and other additives in the coreadditives in the core

acoustic (D) high density core special dimensional p

configuration thermal insulatingthermal insulating

bonded to an expanded polystyrenepolystyrene

Gypsum board useGypsum board use standard boards to 65%RH standard boards to 65%RH impregnated boards

permanently to 75 %RHpermanently to 75 %RHfor a short term to 100 %

? Basement, showers?

Gypsum fiberboardsGypsum fiberboards(80%) ll l fib (20 %) gypsum (80%) + cellulose fibers (20 %)

no paper on surface higher bulk density higher strength better fire resistance in the higher humidity

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AnhydriteAnhydriteanh dro s CaSO + acti ator anhydrous CaSO4 + activator

activators: lime, cement, sulphates slow setting even with activator used for self-leveling screedsused for self leveling screeds

Self-leveling screedsSelf-leveling screeds contains gypsum or anhydrite + plasticizer + contains gypsum or anhydrite + plasticizer +

sand (1:1 1:2) d f d fl h ti very good for under-floor heating

used only in interiors

Air limeAir lime

calcium oxide CaO or calcium hydroxidecalcium oxide CaO or calcium hydroxide Ca(OH)2 with different purity

known from ancient days (Assyrians,y ( y ,Egyptians, Greeks, Romans.....)

Building limes classificationBuilding limes classification

EN 459 Building lime

Air lime Hydraulic limeAir lime Hydraulic lime

Calcium lime Dolomitic limeHydraulic lime HL

Natural hydraulic lime NHLlime NHL

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Air lime manufacturingAir lime manufacturing

Raw material: limestone calcite chalk (CaCO3)limestone, calcite, chalk (CaCO3) dolomitic limestone (CaCO3+MgCO3) dolomite (CaCO3MgCO3)

Air lime manufacturingAir lime manufacturing

Pieter van Laer (1599 1642)

Air lime manufacturingAir lime manufacturing

step 1 burning (decarbonation) quicklime CaOq crushed, ground, pulverized

unstable in the presence of unstable in the presence of moisture and CO2

step 2 slaking (hydration)hydrated lime Ca(OH)2hydrated lime Ca(OH)2

lime slurry, putty, milk of lime powder

Air lime burning 900 - 1200C decarbonation in

Air lime burning 900 1200 C decarbonation in kilns

CaCO + heat CaO + COCaCO3 + heat CaO + CO2CaCO3MgCO3 + heat CaO + MgO + 2CO2

lower temperature - soft-burned lime -more reactive, porous, suitable for mortarshi h h d b d li higher temperature hard-burned lime less reactive, denser, suitable for AAC t hi h t t b d li too high temperature overburned lime

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Lime kilnLime kiln

Crypta BalbiRoma

Pacold lime kilnVelk Chuchle

Quicklime CaOQuicklime CaO

large lump lime

crushed lime 25 mm ground lime 2 5 mmground lime 2,5 mm pulverized lime 0,2 mm pelletized lime

Quicklime hydrationQuicklime hydration

Reaction between quicklime and water:

CaO + H O Ca(OH) + heatCaO + H2O Ca(OH)2 + heat highly exothermic processhighly exothermic process

Types of hydration:Types of hydration:

dry hydration Ca(OH)2 in powder 2 slaking Ca(OH)2 in suspension

( l tt ilk f li )(slurry, putty, milk of lime)

Quicklime slaking CaO reacts with the amount of water

Quicklime slaking

much higher than the quantity, necessary for the reaction

240-320 l of water /100 kg of quicklime lime putty slurry milk of lime lime putty, slurry, milk of lime

a great quantity of heat is released material can splatter danger of burns!

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Quicklime slakingQuicklime slaking the volume expansion (due to absorbed

water) - the greater the expansion, the better lime min. 2,6 l slurry from y

1 kg of quicklime

the lime putty has to mature from a few hours to many days (to allow the slaking of allto many days (to allow the slaking of all particles)

historically lime was slaked over a period historically lime was slaked over a period of at least six months (even 10 years)

Quicklime slakingQuicklime slakingFactors affecting the slaking process:g g p quality of quicklime specific surface specific surface temperature (slightly under 100 C) amount of water added

to much water drowning (killing) the limeImperfect slaking: uneconomical (unskillful slaking may reduceuneconomical (unskillful slaking may reduce

the paste to less than two volumes) the unslaked particles may slake later in the unslaked particles may slake later in

the mortar

Dry hydration of quicklimeDry hydration of quicklime adding water under controlled conditions

reaction with just the right amount of waterreaction with just the right amount of water

65 70 l of water / 100 kg of quicklime

powder hydratedpowder hydrated lime

special equipment -- lime hydrator

lime putty (powder + water) has to mature

Setting and hardening of air g glime

Setting physical reaction (drying out of colloid gel)colloid gel)

Hardening carbonation

Ca(OH)2 + CO2 + nH2O CaCO3 + (n+1)H2O

slowd d CO i d RH depends on CO2 concentration and RH and air temperature

Lime plasters should be left min. 1 month without painting !

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Lime cycleLimestoneCarbonation

(hardening)CaCO3 Burning

(hardening)

CO+ CO2

C O QuickDrying

- CO22+ H2O

CaOCa(OH)2Quicklime

Lime

Ca(OH)2mortar Slaking

Using

+ H2O

Ca(OH)2Using

Hydrated limeLime slurry, lime putty

Air lime useAir lime uset d l t mortars and plasters

prepared in-situ

ready-made mixtures

sand lime bricks sand lime bricks autoclaved aerated concrete lime wash white or color paint

di i f t t disinfectant

Water glassWater glassSodium silicate aqueous solution or solidSodium silicate aqueous solution or solid

compound of sodium oxide (Na2O) and silica (silicon dioxide SiO )(silicon dioxide, SiO2)

sodium, potassium, lithium produced by burning of soda ash (Na2CO3) and silica

sand (SiO2) in a furnace (1000 - 1400 C) or ( 2) ( )dissolving silica sand under pressure in a heated aqueous solution of soda (NaOH)

hardening: adding of the weak acids (CO2, organic esters)organic esters)

usually mixed with fine sand

Water glassWater glass

Properties: soluble in water alkaline solutionsoluble in water alkaline solution stable in neutral and alkaline solutions in acidic solutions reacts and hardens -

hard glassy gela d g assy ge good resistance to high temperatures

(int mescent)(intumescent)

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Water glass useWater glass use timber treatment wood

preservation binders exposed to heatbinders exposed to heat

or fire concrete and masonry concrete and masonry

treatment reducing of their porositytheir porosity

refractory use - with light eight aggregateslightweight aggregates

water treatment soil stabilization

Magnesia binderMagnesia binder Sorel cement based on MgO and MgCl2g g 2 prepared by mixing burned magnesia

(MgO) with magnesium chloride(MgO) with magnesium chloride hardening formation of magnesium

oxychloridesoxychlorides high strength good fire resistance good resistance to abrasion high elasticity

Magnesia binder useMagnesia binder use

floorings (cast floors) Xylolithy

fire protection productsf fiber boards

grinding wheels,grinding wheels, abrasive stones

XylolithXylolith mixture of magnesia cement, sawdust, and g

wood flour, with an addition of finely dispersed mineral substances (talc, asbestos, p (marble flour) and alkali-resistant pigments

the seamless floors in residential and publicthe seamless floors in residential and public buildings

Villa Tugendhat, BrnoLudwig Mies van der Rohe, 1930

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GeopolymersGeopolymers synthetic aluminosilicate polymers formed in synthetic aluminosilicate polymers formed in

alkaline environment at normal temperaturet i l th l ti t d l raw material e.g. thermal activated clays

(metakaolin, fly ash) + strong alkali activator fire-resistant, blast-resistant and acid-resistant

GeopolymersGeopolymers Prof. Joseph Davidovits

349,- /1kg

399,- /1kg

http://www.youtube.com/watch?v=znQk_yBHre4

Geopolymer concretesGeopolymer concretes

+ high strength+ fire resistant

- price !!- efflorescence+ fire resistant

+ lower energy ti

efflorescence- difficult preparation

consumption+ chemically resistantc e ca y es sta t+ durability

ConcreteConcrete

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ConcreteConcreteEN 206 1 Concrete Part 1 SpecificationEN 206-1 Concrete - Part 1: Specification,

performance, production and conformity:

material formed by mixing cement, coarse and fine aggregate and watercoarse and fine aggregate and water, with or without the incorporation of d i t d dditi hi hadmixtures and additions, which

develops its properties by hydration of the cement

Concrete componentsConcrete componentsbi d ( t) binder (cement)

aggregatesaggregates

mixing water

admixtures (up to 5 % of cement mass)mass)

additions (in powder)

reinforcement (steel bars, grids, fibers)fibers)

Terms (EN 206 1)Terms (EN 206-1)fresh concrete concrete hich is f ll fresh concrete - concrete which is fully mixed and still in a condition that is capable of being compacted by the chosen method

h d d t t hi h i hardened concrete - concrete which is in a solid state and which has developed a certain strength

Terms (EN 206 1)Terms (EN 206-1) designed concrete concrete for which designed concrete - concrete for which

the required properties and additional characteristics are specified to thecharacteristics are specified to the producer who is responsible for providing a concrete conforming to the required g qproperties and additional characteristics

prescribed concrete - concrete for whichprescribed concrete concrete for which the composition of the concrete and the constituent materials to be used are specified to the producer who is responsible for providing a concrete with the specified composition

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Concrete types according the yp gbulk density

normal weight concrete2000 2600 kg.m-3

light weight concrete light-weight concrete800 2000 kg.m-3800 000 g

heavy-weight concrete> 2600 kg.m-3

Concrete types according the place of manufacture

site-mixed concrete - concrete produced on the construction site by the user of theon the construction site by the user of the concrete for his own use

ready-mixed concrete - concrete delivered ready-mixed concrete - concrete delivered in a fresh state by a person or body who is not the user. Ready- mixed concrete is also:ot t e use eady ed co c ete s a so concrete produced off site by the user concrete produced on site, but not by the user

precast concrete product - concrete product cast and cured in a place other than p pthe final location of use

Concrete worksConcrete works

mixingt t transport

placingp g compacting

f k formwork removal

curing

On site mixed concreteOn site mixed concrete

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On site mixed concreteOn site mixed concrete

mobile concrete batching plantbatching plant

Ready mixed concreteReady mixed concrete

Concrete transportp Concrete consolidationTo get rid of the air voids: statical compacting

rodding, tamping, rammingg, p g, g dynamical

vibrating (immersion vibrating (immersion or surface vibrators)

combined combined pressure and jolting

self compacting self- compacting plasticizers

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Segregation of concreteSegregation of concrete

the separation of the constituent materialsconstituent materials of concrete usually by over-vibrationby over vibration

- the denser aggregates ttl t th b tt hilsettle to the bottom while

the lighter cement paste tends to move upwardstends to move upwards

Concrete curingConcrete curing any procedure that maintains proper any procedure that maintains proper

moisture and temperature of the concrete to ensure continuous hydrationensure continuous hydration

if the water is allowed to evaporate the h d ti d th t h i khydration ceases and the concrete shrinks cracks occur !

Concrete curing methodsConcrete curing methods ponding wrapping in plastic or wet clothpp g p spraying on temporary curing

membranemembrane

Minimal time of curingMinimal time of curing

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Concrete constituentsCementCement

binder mi ing ith ater cement binder mixing with water cement paste cement stone

has to conform with EN 197-1

most expensive part of the concrete as Iittle cement as possible should beas Iittle cement as possible should be used

Cement dosageCement dosageMinimal:Minimal: unreinforced concrete: 200 kg /1 m3

of finished concreteof finished concrete reinforced concrete :

- sheltered: 240 kg/1 m3- unsheltered: 260 kg/1m3g- watertight constructions: 300 kg/1 m3

Strength increases to the amount 450 kg/1 m3 higher dosage is notg g geconomical !

Other bindersOther binders polymers + high strength good polymers + high strength, good

resistance against aggressive environment fastaggressive environment, fast setting and hardening

demanding production price- demanding production, price , fire resistance

h lt d asphalts roads gypsum - only inside of the building clays - low strength, volume

instabilityy

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A tAggregates Aggregatesgg egates

granular mineral material suitable for use in concrete.

aggregates may be natural, artificial or recycled from material previously used in y yconstruction

gravels, stone and sands form the granulargravels, stone and sands form the granular structure, which must have its voids filled as completely as possible by the binder gluecompletely as possible by the binder glue

approximately 80 % of the weight and 70 75% of the volume of the concrete75% of the volume of the concrete

Standards for aggregatesStandards for aggregatesEN 12620 A t f t EN 12620 Aggregates for concrete - normal and heavy-weight aggregates

EN 13055-1 - Lightweight aggregates. g g gg gLightweight aggregates for concrete, mortar and grout

EN 13043 Aggregates for bituminous mixtures and surface treatments

EN 13055-2 Lightweight aggregates for bituminous mixtures and surface treatments

Standard and special aggregatesBulk

BulkBulk

Bulk

BulkBulk

Bulk

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Origin of aggregatesOrigin of aggregates natural aggregate - aggregate from mineral

sources which has been subjected to nothing more than mechanical processingmore than mechanical processing

manufactured aggregate - aggregate of mineral origin res lting from an ind strialmineral origin resulting from an industrial process involving thermal or other modificationmodification

recycled aggregate - aggregate resulting from the processing of inorganic materialfrom the processing of inorganic material

recovered aggregate - aggregate recovered from wash water or fresh concretefrom wash water or fresh concrete

Aggregates propertiesAggregates propertiesRequired for mix design:Required for mix design: grading durability particle shape and surface texturep p

rounded aggregates - more workable mix angular aggregates - harder to place, work andangular aggregates harder to place, work and

compact concrete ,but c. is stronger abrasion and skid resistanceabrasion and skid resistance unit weights and voids

b ti d f i t absorption and surface moisture

GradationGradationid l filli f ideal filling of space

Apollonius from Perga(262-190 p.n.l.)

Aggregates gradationAggregates gradation

Particle-size distribution has an impact on:b lk d it d t th f t bulk density and strength of concrete

workability (consolidation, finishability, y ( , y,and pumpability)

cost cost

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Ideal gradationg

Fuller equationFuller equationi

i Ddy 100max

i D

Bolomey, EMPA, Kenedy, Hummel, Valete

i i ll t f ti b tt minimally two fraction, better threethree

F : C = 1: (1,5 2)F : C 1: (1,5 2)

Physical properties (EN 12620)Physical properties (EN 12620) resistance to fragmentation of coarseresistance to fragmentation of coarse

aggregate Los Angeles coefficient resistance to impact

resistance to wear - micro-Deval resistance to polishing and abrasion particle density and water absorptionp y p bulk density durabilityy

freeze/thaw resistance volume stability - drying shrinkage alkali-silica reactivity

Chemical properties (EN 12620)Chemical properties (EN 12620)

chlorides sulfur containing compoundsg p

acid-soluble sulfate total sulfur

other constituents constituents which alter the rate of setting andconstituents which alter the rate of setting and

hardening of concrete organic substances constituents which affect the volume stabilityconstituents which affect the volume stability

of air-cooled blastfurnace slag carbonate content of fine aggregates forcarbonate content of fine aggregates for

concrete pavement surface courses

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Organic impurities in aggregatesOrganic impurities in aggregates

h t t f l humus content (decaying vegetation), fulvoacids (humic acids) retarding effect on cement colorimetric tests (NaOH, KOH) comparison with standard color

sugars - influence on setting and hardening decrease of strength

carbonate contentca bo ate co te t lignite and coal particles may cause brown stains

and/or popouts to appear at the surfacep p pp

Sulfur content in aggregatesSulfur content in aggregates

total sulfur content - expressed as total sulfur content - expressed as percentage by mass of the aggregate

max 1% (2 % for blastfurnace slag) max. 1% (2 % for blastfurnace slag)

lfid (F S PbS) f lf t sulfides (FeS2, PbS) - source of sulfates sulfates (CaSO4, PbSO4 ) - sulfate corrosion

Chlorides in aggregatesChlorides in aggregates

chlorides may dissolve in the mixing water chlorides may dissolve in the mixing water and promote corrosion of steel

i hl id t t i d maximum chloride content is expressed as percentage of water-soluble chloride ion

t t b f bi d tcontent by mass of combined aggregate plain concrete 0,15 %

reinforced concrete 0 06 % reinforced concrete 0,06 % prestressed concrete 0,03 %

Alkali - silica reactionAlkali - silica reaction certain aggregates can react with alkaline certain aggregates can react with alkaline

hydroxides present in the pore fluids of concreteconcrete

under adverse conditions and in the presence of moisture this can lead to expansion andof moisture this can lead to expansion and subsequent cracking or disruption of the concrete ASRconcrete - ASR

less common is alkali-carbonate reaction

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Alkali-silica reaction - ASRAlkali-silica reaction - ASR occurs over time in concrete between the occurs over time in concrete between the

highly alkaline cement paste and reactive non-crystalline (amorphous) silicanon crystalline (amorphous) silica

formation of a swelling gel of calcium silicate hydrate (CSH gel)y ( g )

Water

WaterWater

mixing water for hydrationfor hydration for workability

curing water curing water

Mixing water - EN 1008Mixing water - EN 1008 potable waterp

suitable for use in concrete without testing water recovered from processes in the concrete

industryindustry normally suitable for use in concrete, but shall conform

to the requirements of standard water from underground sources water from underground sources natural surface water and industrial waste water

both suitable for use in concrete, but shall be tested sea water or brackish water

may be used for concrete without reinforcement or other embedded metalreinforcement or other embedded metal

not suitable for the production of reinforced or prestressed concrete

sewage watersewage water not suitable for use in concrete

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AdmixturesAdmixtures AdmixturesAdmixtures

EN 934-2: material added during the mixingmaterial added during the mixing

process of concrete in small quantities related to the mass of cement (0 2 5related to the mass of cement (0,2 5 %) to modify the properties of fresh or hardened concrete

mostly liquidmostly liquid

Admixture types (EN 934 2)Admixture types (EN 934-2) water reducing/plasticizingwater reducing/plasticizing high-range water reducing/superplasticizing water retaining a e e a g water resisting air entrainingg set accelerating hardening acceleratingg g set retarding dual function admixtures

set retarding/water reducing/plasticizing set retarding/high-range water

d i / l ti i ireducing/superplasticizing set accelerating/water reducing/plasticizing

Plasticizing and gsuperlasticizing admixtures

Enables the water content of a given concrete mix to be reduced without affecting themix to be reduced without affecting the consistence, or increases the workability without changing the water content, orwithout changing the water content, or achieves both effects reduction 5% reduction 5%

(plasticizer)reduction 12% reduction 12% (superplasticizer)

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Plasticizing/Water reducing d i t

admixture is adsorbed on to the cement admixtures

particles and lowers the inter particular attraction so that flocs of cement break up p

lignosulphonate hydrocarbolic acids salts carbohydrates

SuperplasticizersSuperplasticizers increased fluidity increased fluidity

flowing, self-leveling, self-compacting concretet ti d ti d d penetration and compaction round dense

reinforcement

d d W/C ti reduced W/C ratio: very high early strength, very high later age strengths >100 MPa reduced shrinkage (especially if combined with

reduced cement content improved durability by removing water to reduce

bilit d diff ipermeability and diffusion

SuperplasticizersSuperplasticizers Sulphonated melamine formaldehyde Sulphonated melamine formaldehyde

condensates (SMF) 1625% water reduction little or no retardation16 25% water reduction, little or no retardation very effective at low temperatures

Sulphonated naphthalene formaldehyde p p ycondensates (SNF) 1625% water reduction. tend to increase the entrapment

of larger, unstable air bubbles Polycarboxylate ether

superplasticizers (PCE)20 35% t d ti 2035%+ water reduction

relatively expensive

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