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Mineral Admixtures & Blended Cements
Primary purposes of adding mineral admixtures or
supplementary cementing materials in concrete To replace cement (economical & technical reasons, and
environmental consideration)
To improve the workability of fresh concrete
To reduce heat and early temperature rise To enhance the durability of hardened concrete
Mineral admixtures are divided into 3 main categories
1. Pozzolanic materials
2. Cementitious materials
3. Non-reactive materials (ground lime stone, silica flour)
May react weakly with cement under certain conditions
Main use, for workability purposes in masonry cements
supplementary cementing materials
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Pozzolanic Materials
History and origins
Greeks: Addition ofnaturally occurringmaterials from volcanicorigin to hydrauliclimes
Romans adopted &extended Greektechnology (e.g.Parthenon)
[Alkali activated binder,e.g. fly ash and/or ggbs]
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Pozzolanic Materials
Pozzolan
Pozzouli, a town in the Bay of Naples that was the source
of a highly prized deposit of ash from Mt. Vesuvius The name pozzolan is now applied to any alumino-
silicate materials, of either natural or industrial origin
Powder: naturally occurring or to be ground to cement
fineness(Mindess et al 2003)
Rice husk ash (RHA)Palm Oil Fuel Ash (POFA)
Abundant sourcesMuch have been studiedLittle in actual use
WHY?
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Pozzolanic Materials
Natural Pozzolans
Volcanic ask etc
By-product materials
Fly ashinorganic, non combustible residue of
powdered coal after burning in power plants Silica fumea by-product in the manufacture of Silicon
metal and alloys
Rice husk ashsiliceous residue that remains after the
rice husks are burnt under controlled conditions Calcined clay under controlled temperatures (700-900 oC)
to produce a highly reactive amorphous aluminosilicate(metakaolin)
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Composition
ASTM C 618 for fly ash & natural pozzolans
Class F fly ash (BS EN 450-1: 2005)
produced from bituminous and sub-bituminous coals
(SiO2+Al2O3+Fe2O3) 70% (BS EN 450-1 not less than 70%) Class C fly ash
produced from lignitic coals
(SiO2+Al2O3+Fe2O3) 50%BS EN 450-1: reactive SiO2content at least 25 % by mass
(Mindess et al 2003)Typical CEM l 20 6 3 65
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Composition
Crystalline components (identified by X-ray diffractionmethod)
A good pozzolan shouldhave a high fraction ofreactive glassy oramorphous material
Most pozzolanic materialscontain variousquantities of inertcrystalline phases
Examples
Class F ash: quartz, mullite, hematite, magnetite
Class C ash: free CaO, anhydrite (CaSO4), C3A, C2S, etc
(Mindess et al 2003)Low-calcium fly ashClass FHigh-calcium fly ashClass C
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Composition (contd)
Minor components
Alkali oxides in situations where pozzolanic materials are used to control
AAR, alkali content of the materials should be determined
(BS EN 450-1 Na2O equivalent not to exceed 5.0% by mass)
Unburnt carbon (determined by Loss on Ignition) In SF; 1-2%
In FA: 0.5-3% (sometimes as high as 25%)
In RHA: 3-8%
Concern for air-entrainment
Color of concrete
SO3and periclase (crystalline MgO)
unsoundness
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Physical Characteristics
(Mindess et al 2003)
Note:Surface area > 1 m2/g
(1000 m2/kg)Air permeability not suitable
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silica fume small size packing effect
reduce bleeding, reducethe size of capillary pores
fly ash
(Mindess et al 2003)
(Mindess et al 2003)
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Pozzolanic Reactions Principal reaction: amorphous silica reacts with CH
from cement hydration
CH + S + H C-S-H Composition of C-S-H from pozzolanic reactions
In cases of fly ashes or natural pozzolans: not very differentfrom that formed in regular hydration, C/S is slightly lower
generally In cases on silica fume or rice husk ash, C/S is significantly
different from that of cement hydration, ~1.0
Kinetics of the reaction is similar to the slow rate ofhydration of C2S. Thus, the addition of pozzolan has a
similar effect to higher C2S content in cement Reduce early heat evolution and early strength, but not
long-term strength so long as water is available
Increase the overall solid volume, reduce the porosity,
increase strength and durability
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Pozzolanic Reactions The extent of a pozzolanic reaction can be followed by
monitoring over time the decrease in CH derived from
hydrating of CEM 1
Slow rate of pozzolanic reaction requires prolonged periodof moist curing (particularly for durability of cover concrete)
Pozzolanic reaction is more temperature sensitive thanregular cement hydration (tropical climate beneficial)
(Mindess et al 2003)
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Ground granulated blast-furnace slag (GGBFS)
Obtained from the production of iron
Typical composition CaO = 35-45%, SiO2= 32-38%, Al2O3= 8-16%,
MgO = 5-15%, Fe2O3
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Blended Cements - US
- Setting time
- Strength
- Heat
- Sulfateresistance
Note:
Compare withEN 197-1specifications
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Examples of Cementitious Materials
TYPICAL PROPERTIES OF CEMENTITIOUS MATERIALS
COMPOUNDSPERCENTAGE BY MASS
CEM I GGBS Fly Ash SFCaO 65(63) 40(40) 3(1) [20]# 0.15(0)
SiO2 20(22) 38(35) 50(50) [35]# 92(90)
Al2O3 5(6) 11(8) 28(25) [20]# 0.7(2)
Fe2O3 3.5(3) 0.3(0) 10.4(10) [5]# 1.2(2)Na2O 0.1 0.4 0.7 1.0
K2O 0.7 0.8 2.5 1.5
MgO 0.1 7.5 2.0 0.2
Densitykg/m3
3.13.2 2.9-3.0 2.3-2.6 2.2-2.4
Fineness m2/kg 300400 350600 400 - 700 20,000*
(Data from a different source)
*Approximate value by nitrogen absorption method#[High Lime pfa]
C24
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Mineral AdmixtureEN Standards
Fly Ash: [No SS EN]BS EN 450-1: 2005, Fly ash for concretePart 1: Definition,specifications and conformity criteria
BS EN 450-1: 2005, Fly ash for concretePart 2: Conformityevaluation
Silica Fume [SS EN 13263]
BS EN 13263-1: 2005, Silica fume for concretePart 1: Definitions,requirements and conformity criteria
BS EN 13263-1: 2005, Silica fume for concretePart 2: Conformityevaluation
Ground granulated blast furnace slag [SS EN 15167]BS EN 15167-1: 2006, Ground granulated slag for use in concrete,mortar and groutPart 1: Definitions, specifications and conformitycriteria
BS EN 15167-2: 2006, Ground granulated slag for use in concrete,
mortar and groutPart 2: Conformity evaluation
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Specification for Supplementary Cementitious Materials
Type II Addition
Supplementary Cementitious (or cementing) Materials (SCM)
for Concrete
ground granulated blastfurnace slag (ggbs)
fly ash (includes co-combustion, pulverized fuel ash - pfa)
condensed silica fume (csf) SCM added to Portland cement (CEM I) which provides
calcium hydroxide needed for pozzolanic reaction
Stage 1 Reaction
PC (CEM I) + water ---------> CSH + CH
Stage 2 - Pozzolanic (Secondary) Reaction
SCM + CH + water ----------> CSH
(CSH = calcium silicate hydrates, CH = calcium hydroxide)
Fl A h
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Specification for Supplementary Cementitious MaterialsFly AshBS EN 450 : 2005 Fly ash for concrete
Part 1: Definition, specifications and conformity criteria
Part 2: Conformity evaluation
Fly AshDefinition
Fly ashfine powder of mainly spherical, glassy particles, derived fromburning of pulverised coal, with or without co-combustionmaterials, which has pozzolanic properties and consists
essentially of SiO2and Al2O3, the content of reactive SiO2 asdefined and described in EN 197-1 being at least 25% by massFly ash is obtained by electrostatic or mechanical precipitation of dust-
like particles from the flue gases of furnaces fired with pulverisedcoal, with or without co-combustion materials
Fly ash may be processed, for example by classification, selection,sieving, drying, blending, grinding or carbon reduction, or bycombination of these processes, in adequate production plants.Such processed fly ash may consist of fly ashes from differentsources, each conforming to the definition given in this clause. Ifone or more incoming fly ashes are obtained from co-combustion,then the processed fly ash shall be considered as fly ash fromcombustion
C31
Fl A h
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Specification for Supplementary Cementitious MaterialsFly Ash
Test CementClause 3.3Selected brand of Portland cement of type CEM I, strength class 42,5 or
higher, conforming to EN 197-1 to be used for carrying out the testsneeded to evaluate conformity to the requirements of 5.3.2 (Activityindex), 5.3.3 (Soundness), 5.3.5 (Initial setting time) and 5.3.6 (Waterrequirement).
Test cement is selected by the fly ash producer and is further
characterised by its fineness and contents of tricalcium aluminateand alkalis as follows:
Fineness (Blaine): At least 300 m2/kg
Tricalcium aluminate: 6% to 12%
Alkalis (Na2O equivalent): 0,5% to 1,2%
Note: Performance with job cement and concrete may be very different,particularly in the case of combination in concrete production,when the Portland cement of type CEM I is not from a singlesource of consistent quality.
[Fly ash not yet available locally, no import without G-to-G agreementon waste across national boundaries, only as pre-blended cements]
C32
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Specification for Supplementary Cementitious MaterialsFly Ash
Chemical RequirementsClause 5.2
Chemical composition expressed as proportions by mass of dry fly ashLoss on ignition (EN 196-2, but using ignition time of 1h)
Category A: Not greater than 5,0% by mass
Category B: Between 2,0% and 7,0% by mass
Category C: Between 4,0% and 9,0% by mass
Chloride (EN 196-21 expressed as Cl-ion)
Not greater than 0,10% by mass
Sulfuric anhydride (EN 196-2 expressed as SO3)
Not greater than 3,0% by mass
Free calcium oxide (EN 451-1)Not greater then 2,5% by mass, if > 1,0% conformity to soundnessneeded
Reactive calcium oxide (EN 197-1:2000 method of calculation)
Not to exceed 10.0% by mass, not required if total content of
calcium oxide 10,0%
S ifi ti f S l t C titi M t i l Fl A h
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Specification for Supplementary Cementitious MaterialsFly Ash
Chemical Requirements - continued
Silicon dioxide (SiO2) aluminium oxide (Al2O3) and iron oxide (Fe2O3)
(EN 196-2 modified as indicated in 5.2.1)Sum of these not less than 70% by mass, deemed to be satisfiedfor combustion of pulverised coal only
Total content of alkalis (EN 196-21 as Na2O eqv)
Not to exceed 5,0% by massMagnesium oxide (EN 196-2)
Not greater than 4,0% by mass, deemed to be satisfied forcombustion of pulverised coal only*
Soluble phosphate (Annex Cnormative)
Not greater than 100 mg/kg, deemed to be satisfied forcombustion of pulverised coal only*
*Note: Currently, coal fired power generation stations may addmunicipal solid waste as fuel (up to 10% and
more in future) and defined as co-combustion
S ifi ti f S l t C titi M t i l Fl A h
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Specification for Supplementary Cementitious MaterialsFly Ash
Physical RequirementsClause 5.3
Fineness (EN 451-2)
Ash retained when wet sieved on a 0,045 mm mesh sieve shallfall within the limits of categories specified below:Category N: 40% by mass 10% of declared valueCategory S: 12% by mass (no tolerance)
Activity index (EN 196-1)
Ratio (in %) of compressive strength of standard mortar bars,prepared with 75% test cement plus 25% fly ash by mass, tocompressive strength of standard mortar bars prepared with100% test cement, when tested at the same ageStandard mortar bar for compressive strength at 28 days and at
90 days
75% and 85% respectivelySoundness (EN 196-3)Expansion determined on 30% fly ash and 70% test cement bymass 10 mmWhere free calcium oxide content of fly ash 10% by mass,requirement deemed to be satisfied
Fl A h
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Specification for Supplementary Cementitious MaterialsFly Ash
Physical Requirementscontinued
Particle density (EN 196-6)
Shall not deviate by more than 200 kg/m3 from value declaredby producer
Initial setting time (EN 196-3)Determined on a 25% fly ash plus 75% test cement by masscement paste 120 min longer than initial setting time of a
100% by mass test cement paste that meets requirements inEN 197-1 when test aloneFly ash from combustion of pulverised coal only shall bedeemed to satisfy this requirement
Water requirement (method in Annex B (normative) Method of
determining the water requirement for Category S fly ash95% of that for test cement alone (not required for category N)
Durability RequirementsFly ash conforming to definition in 3.2, fulfilling chemical
requirements in 5.2 and physical requirements in 5.3 deemedto satisfy durability requirements
S ifi ti f S l t C titi M t i l Fly Ash
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Specification for Supplementary Cementitious MaterialsFly Ash
Fly AshCurrently there is no fly ash being produced in Singapore, but new
coal fired electricity power plant may be built in the future
Currently fly ash cannot be directly import (classified as a waste)Fly ash may be preblended with CEM I as a blended cement (conforming
to EN 177-1 CEM II/A, CEM ll/B ) and can then be importedOther cement types with fly ash and other supplementary cementitious
materials, e.g. ggbs, limestone powder, may also be used inpreblended cements (CEM IV and CEM V) and can be imported
Durability RequirementsFly ash conforming to definition in 3.2, fulfilling chemical requirements
in 5.2 and physical requirements in 5.3 deemed to satisfydurability requirements
The k-value concept (EN 206-1, Subclause 5.2.5.2) permits type lladditions (fly ash and silica fume) to be taken into account byreplacingwater/cement ratio with water/(cement + k x addition) ratio
[Note: BS 8500 (SS 544) provides alternate specific recommendationsfor different exposure conditions in terms of cement type,
minimum cement content and maximum water-cement ratio]
S ifi ti f S l t C titi M t i l GGBS C31
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Specification for Supplementary Cementitious MaterialsGGBSSS EN 15671 : 2008 Ground granulated blast furnace slag for use in
concrete, mortar and groutPart 1: Definitions, specifications and conformity criteria
Part 2: Conformity evaluationGGBSDefinition
Granulated blastfurnace slagvitrified material made by rapid coolingof a slag melt of suitable composition, obtained by smelting ironore in a blastfurnace, consisting of at least two thirds by mass ofglassy slag and possessing hydraulic properties when suitablyactivated
NOTERapid cooling includes quenching in water (granulation) andprojecting through water and air (pelletisation)
Ground granulated blastfurnace slagfine powder made by grindinggranulated blastfurnace slag
Clause 4ConstituentsThe main constituent shall be granulated blastfurnace slag as defined.
Its chemical composition shall consist of at least two-thirds bymass of the sum of calcium oxide (CaO), magnesium oxide (MgO)and silicon oxide (SiO2). The remainder shall be aluminium oxide
(Al2O3) together with small amount of other components. The ratioby mass (CaO + MgO)/(SiO2) shall exceed 1.0.
C31
Specification for Supplementary Cementitious Materials GGBS
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Specification for Supplementary Cementitious MaterialsGGBS
Chemical RequirementsClause 5.2
Chemical properties of ground granulated blastfurnace slag shall
conform to the requirements in Table 1Table 1Chemical requirements given as characteristicvalues
Property Test reference Requirements a
magnesium oxide EN 196-2 18 %
sulfide EN 196-2 2.0 %sulfate EN 196-2 2.5 %
loss on ignition, corrected for oxidationof sulfide
EN 196-2 3.0%
chloride b EN 196-2 0.10%
moisture content Annex A 1.0 %a Requirements are given by mass of the ground granulated blastfurnace slagb Ground granulated blastfurnace slag may contain more than 0.10 % chloride
but in that case the maximum chloride content, as a value not to be exceeded,shall be stated on the packages of the documents (see Clause 6)
Specification for Supplementary Cementitious Materials GGBS
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Specification for Supplementary Cementitious MaterialsGGBS
Physical RequirementsFineness (EN 196-6)
Specific surface not less than 275 m2/kg
Requirements when combined with test cement
Initial setting time (EN 196-3)Combination (by mass) of 50% ggbs with 50% test cement shall
not be more than twice as long as that of test cement on its own Activity index (EN 196-1)Ratio (in %) of compressive strength of combination (by mass)of 50% ggbs with 50% test cement to the compressivestrength if test cement on its own with water : combination ratio
and water : cement ratio both at 0,50Activity index: at 7 days and at 28 days shall be not less than45% and 70% respectively
Specification for Supplementary Cementitious Materials GGBS
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Specification for Supplementary Cementitious MaterialsGGBS
Test CementThe test cement shall conform to EN 197-1 and shall be selected by
the ground granulated blastfurnace slag manufacturer, subject tothe following restrictions:
- CEM I, of strength class 42,5 or higher;
- Blaine fineness shall be at least 300 m2/kg;
- tricalcium aluminate shall be between 6% and 12%;
- alkali (Na2O equivalent) content shall be between 0.5% and 1,2%
(same requirements as test cement for fly ash)
Durability Requirements
GGBs conforming to SS EN 15167-1: 2008 is deemed to satisfydurability requirements, provided that other requirement fordurability of concrete in relevant standards and/or regulationsvalid in the place of use are fulfilled.
The k-value concept (EN 206-1, Subclause 5.2.5.2) covers only type lladditions (fly ash and silica fume) without any provision for GGBS
in a similar manner (see SS 544-1: 2009 for guidance)
Specification for Supplementary Cementitious Materials GGBS
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Specification for Supplementary Cementitious MaterialsGGBS
Evaluation of conformity
Initial type testing and factory production control shall be carried outaccording to relevant clauses in EN 15167-2
Conformity shall be continually evaluated on the basis of testing of spotsamples for properties using test methods and minimum testingfrequency for autocontrol testing by manufacturer as specified in Table 2
Statistical criterion: percentile Pk of 10% for required characteristic value oran allowable probability of acceptance CR(consumers risk) of 5%
Conformity shall be verified either by variables or by attributes, as describedin 8.22 and 8.2.3 and as specified in Table 2
The control period shall be 12 months for the routine situation.
Table 2Properties, test methods and minimum testing frequencies forthe autocontrol testing by the manufacturer or his agent and the
statistical assessment procedureMinimum testing frequency: Routine situation and Initial period for a new
GGBSStatistical assessment procedure: Inspection by Variable or by Attributes
for indicated chemical and physical properties
[Use of combination without producers certified conformity data mayneed to verify conformity by userpre-blended cement preferred]
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Slag Hydration
GGBFS reacts slowly with water, strength developmenttoo slow
Activation of slag by
Soluble sodium salts, NaOH, Na2CO3, NaSiO3
Ca(OH)2
Slags are commonly activated by Portland cement
In slag-cement blends, slag also shows pozzolanicbehavior
Products of slag hydration A mixture of C-S-H and AFm (monosulphoaluminate)
The rate of hydration of activated slag is similar to thatof C2S, as is the heat of hydration
Specification for Supplementary Cementitious Materials Silica Fume
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Specification for Supplementary Cementitious MaterialsSilica Fume
BS EN 13263 : 2005 Silica Fume for concretePart 1: Definition, requirements and conformity criteriaPart 2: Conformity evaluation
Definitions
Silica fume (condensed silica fume, microsilica)
very fine particles of amorphous silicon oxide collected as a by-productof the smelting process used to produce silicon metal and ferro-siliconalloys
Silica fume slurry
homogeneous, pH regulated liquid suspension of silica fume in water,typically with a dry content of 50% by mass, corresponding to about700 kg of silica fume per m3of slurry
Densified silica fumesilica fume that has been treated to increase the bulk density by particleagglomeration, the bulk density typically being above 500 kg/m3
Undensified silica fume
silica fume taken directly from the collection filter, the bulk density
typically being in the range 150 kg/m3to 350 kg/m3
Specification for Supplementary Cementitious Materials Silica Fume
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Specification for Supplementary Cementitious MaterialsSilica Fume
Chemical Requirements
Silicon dioxide (EN 196-2)SiO2 : not less than 85% by mass
Elemental silicon (ISO 9286)Si : not less than 0,4% by mass
Free calcium oxide (EN 451-1)
CaO : not greater than 1,0%Sulfate (EN 196-2)SO3 : not greater than 2,0% by mass
Total content of alkalis (EN 196-2)Na2O equivalent : to be declared
Chloride (EN 196-2)Cl: not greater than 0,3% by mass, if > 1,0% by mass, upper limitfor characteristic value to be declared by manufacturer
Loss on ignition (EN 196-2)by using ignition time of 1 hour, not greater than 4,0% by mass
A48
Specification for Supplementary Cementitious Materials Silica Fume
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Specification for Supplementary Cementitious Materials Silica Fume
Physical Requirements
Specific surface (ISO 9277)
by nitrogen absorption, not less than 15,0 m2/g, (15 000 m2/kg)nor more than 35,0 m2/g (35 000 m2/kg)
Dry mass content in slurry
dry mass content shall not deviate from value declared by
supplier by more than
2% by mass of slurry when determined bydrying a representative sample of at least 5 g of slurry in a wellventilated oven at (105 5) OC to constant mass
Activity index (compressive strength from mortar barsEN 196-1)
ratio (in %) of compressive strength prepared with 80% test
cement plus 10% silica fume per mass of total binder to thatprepared with 100% test cement, when test at the same age andat least 100% when tested at a mortar age of 28 days
S ifi i f S l C i i M i l
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Specification for Supplementary Cementitious MaterialsSilica Fume
Conformity Criteria
Autocontrol testingbased on testing spot samples by manufacturer for properties,test methods and minimum testing frequencies as specified inTable 1 of EN 13261-1:2005
Conformity criteria for physical and chemical properties and
evaluation procedurebased on spot samples and statistical conformity criteria onthe same basis as for fly ash, either using inspection byvariables or inspection by attributes
[Silica fumein powder or slurry form, product likely to be certified]
[Note: Conformity control for fly ash follows similar approaches as forggbs and silica fume see EN 450-1 and EN 15671 for details]
Specification for Supplementary Cementitious Materials Silica Fume
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Specification for Supplementary Cementitious Materials Silica Fume
Test cement
Selected brand of Portland cement of type CEM I, strength class 42,5 orhigher, conforming to EN 197-1 to be used for carrying the tests
needed to evaluate conformityto the requirement of 5.3.3 inEN 13263-1:2005
Test cement is selected by the silica fume manufacturer and is furthercharacterised by its fineness and contents of tricalcium aluminateand alkalis as follows:Fineness (Blaine): 300 m2/kg to 400 m2/kg (EN 196-6)Tricalcium aluminate: 8% to 12% (EN 196-2)Alkalis (Na2O equivalent): 0,6% to 1,2% (EN 196-2)
The requirements of test cement for silica fume is no t ident ical to thatfor fly ash and GGBS (both with same requirements)
Specification for Supplementary Cementitious Materials Test Cements
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Specification for Supplementary Cementitious Materials Test Cements
Comparison of Test Cements
Test cement requirementsAddition
Fly ash GGBS Silica fumeCEM I, strength class 42,5 or higher 42,5 or higher 42,5 or higher
Blaine finenessm2/kg at least 300 at least 300 300 to 400
Tricalcium aluminate 6% to 12% 6% to 12% 8% to 12%
Alkali (Na2O equivalent) 0,5% to 1,2% 0,5% to 1,2% 0,6% to 1,2%
Note: Test cement for silica fume meets requirements for testing fly ashand GGBS [single test cement for all three preferred]
Cements used as test cements are for conformity testing of additions and
may not be of the same chemical and physical properties as that tobe used in a project.
Initial testing of designed concrete is necessary, unless the particularconcrete has been certified or demonstrated to meet therequirements for the project from inspection records by anaccredited Certification Body (by SAC in Singapore)
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Effects of Mineral Admixtureson Properties of Fresh & Hardening Concrete
Heat of hydration
Reduce the overall heat of hydration
Reduce the rate of heat liberation
Reduce temperature rise in concrete
Workability
Improve cohesiveness
Fly ash and silica fume are particularly beneficial due to theirspherical shape
Addition of fly ash allow w/cm to be reduced while maintaining
slump Silica fume is more beneficial provided that a water reducing
admixture is used (spherical particles provide lubricationamong cement particles; eliminate bleeding and segregation,but make concrete more susceptible to plastic shrinkage)
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Effects on Microstructure
Increase C-S-H & reduce CH leads to more homogenousmicrostructure (CH contributes mainly high pH)
Improve pore structure, reduce overall porosity & poresize
(Mindess et al 2003)
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Effects on Strength Development Develop very good strength over time
May reduce early-age strength, can be offset by reducing
w/cm More reactive pozzolanic materials such as silica fume
and calcined clay will reduce setting time and contributeto early strength
(Mindess et al 2003)
Note:Pozzolanic reactioncontributes to a lotmore strength gainbetween 28 and 56
days than CEM l(control)
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Effects on Drying Shrinkage and Creep
As an approximation, addition of mineral admixtures
does not significantly affect the drying shrinkage orcreep of concrete
However, if volume changes are critical, test should bemade to determine the exact characteristics under the
anticipated service conditions.
[Issues to be covered under hardened concrete]
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Effect on Durability
Used extensively for improving the durability of concrete
Improvements in durability result from the reduction inCH, changes in pore structure, and reduction in w/c
Increase sulfate resistance
Control alkali-aggregate reaction
Reduce chloride diffusion Reduce leaching and efflorescence
EN 206-1 5.2.5.2 k-value concept:
Type II additions to be taken into account by replacing:water/cement ratio with water/(cement + k x addition) ratio in
minimum cement content for durability requirements
BS 8500 (SS 544) for deemed to satisfied approach for differentexposure conditions provides specific minimum cement contentand maximum water/cement ratio directly in relation to specifictypes of cement (i.e. inclusive of k-value concept)
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Linear expansion of concreteexposed to standard ASTM tests forsulphate attack or alkali-aggregate
reaction(More details in topic on aggregates)
Expansion limitfor AAR
Solid lines: w/c=0.5
(Mindess et al 2003)
(Mindess et al 2003)
Note:Better performance with ggbsthan fly ash at commonly usedreplacement rates in both cases
Concrete Constituent Materials Water
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Concrete Constituent MaterialsWater
BS EN 206-1, Mixing water (clause 5.1.4)
Suitability is established for mixing water and for recycled water from
concrete production conforming to EN 1008.
BS EN 1008: 2002 Mixing water for concreteSpecification forsampling, testing and assessing the suitability of water, includingwater recovered from processes in the concrete industry, as mixing
water for concreteThe new standard replaces BS 3148: 1980 and provides more specific
requirements and test methods including water recovered fromprocesses in the concrete industry
Water recovered from processes in the concrete industry shall conformto the requirements of Annex A (normative)
Clause A.4 Requirementsprovides additional requirements to thoseset out in Clause 4 Requirements for all types of water
Constituent Materials for ConcreteWater
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BS EN 1008: 2002 Mixing water for concreteSpecification for sampling, testingand assessing the suitability of water, including water recovered fromprocesses in the concrete industry, as mixing water for concrete
3 Classification of types of water3.1 Portable water
This water is considered as suitable for use in concrete. Such water needsno testing
3.2 Water recovered from processes in the concrete industryThis water, defined in A.2.1, will normally be suitable for use in concrete, but
shall conform to the requirements of Annex A (normative)3.3 Water from underground sources
This water may be suitable for use in concrete, but shall be tested3.4 Natural surface water and industrial waste water
This water may be suitable for use in concrete, but shall be tested3.5 Sea water or brackish water
This water may be used for concrete without reinforcement or otherembedded metal, but is in general not suitable for the production ofreinforced or prestressed concreteFor concrete with steel reinforcement, or embedded metal, the permittedtotal chloride content in the concrete is the determining factor
3.6 Sewage waterThis water is not suitable for use in concrete
Concrete Constituent Materials Water
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Co c ete Co st tue t ate a s ateClause 4 Requirements
The water shall be examined in accordance with the test proceduresstated in Table 1. (see BS EN 1008, Table 1 for details)
Table 2Maximum chloride content of mixing water (see BS EN 1008,Table 2 for details) or maximum value in concrete in 5.2.7 of EN 206-1Sulphates as SO4
2-shall not exceed 2 000 mg/l.Alkaliequivalent sodium oxide content not normally exceed 1 500 mg/lTable 3Requirements for harmful substances or tests for setting time
and compressive strength (see BS EN 1008 Table 3 for details)Clause 4.4 Setting time and strengthWhen tested in accordance with 6.1.4 the initial setting time obtained on
specimens made with the water shall be not less than 1 hour and notdiffer by more than 25% from the initial setting time obtained onspecimens made with distilled or de-ionised water.
The final setting time shall not exceed 12 hours and not differ by morethan 25% from the final setting time obtained on specimens made withdistilled or de-ionised water.
The mean compressive strength at 7 days of the concrete or mortarspecimens, prepared with the water, shall be at least 90% of the mean
strength of corresponding specimens prepared with distilled or de- ionised water
Concrete Constituent Materials Water
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Concrete Constituent Materials Water
Clause 4 Requirements
Table 1Requirements and test procedures for preliminaryinspection of mixing water
Concrete Constituent Materials Water
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Concrete Constituent Materials Water
Clause 4 Requirements
Table 2Maximum chloride content of mixing water
Table 3Requirements for harmful substances
End use Max. chloride content mg/l Test procedurePrestressed concrete or grout 500
6.1.3Concrete with reinforcement orembedded metal
1 000
Concrete without reinforcement or
embedded metal
4 500
Substance Maximum content (mg/l) Test procedure
Sugars 100
6.1.3
Phosphates; expressed as P2O5 100
Nitrates; expressed as NO3- 500
Lead; expressed as Pb2+ 100
Zinc; expressed as Zn2+ 100
Concrete Constituent Materials Water
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Co c ete Co st tue t ate a s ate
Conformity evaluation
The requirements given in this standard are expressed as absolutevalues. For conformity the mixing water shall conform to the
requirements given in Clause 4.
Annex A (normative) Requirements for the use of water recovered fromprocesses in the concrete industry
All water recovered from processes in the concrete industry or
combined water used in concrete shall conform to the requirementsspecified in clause 4 and the following requirements:
Water in storage shall be adequately protected against contamination.Water with a density less than or equal to 1.01 kg/l may be assumed to
contain negligible amount of solid material.
Daily inspection of density of recovered water or combined waterSuitability of recovered water or combined water to Clause 4.
Annex B (informative) Testing scheme for mixing water for concrete(see EN 1008: 2002 for details)
C i f ASTM d BS EN St d d
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Comparison of ASTM and BS-EN Standards
ASTM BS-EN
Portland
cement
C 150Spec for Portland
cements
197-1: 2000 (SS EN 197-1: 2008)
CEM IPortland cementBlendedcements
C 595Spec for blendedhydraulic cements
197-1: 2000 (SS EN 197-1: 2008)
CEM IIPortland comp. cement
CEM IIIblastfurnace cement
CEM IVpozzolanic cement
CEM Vcomposite cement
C 1157Performance Specfor blended hydraulic
cements
Mineraladmixtures
C 618Spec for coal fly ashand raw or calcined naturalpozzolans for use in concrete
450-1: 2005 Fly ash for concreteDefinition, spec, and conformitycriteria
C 989Spec for GGBFS for
use in concrete and mortars
15167-1: 2006 (SS EN 15167: 2008)
Ground granulated blast furnaceslag for use in concrete, mortars,and grouts
C 1240Spec for silica fumeused in cementitious
mixtures
13263-1: 2005 (SS EN 13263: 2008)
Silica fume for concrete
C i f ASTM d BS EN St d d
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Comparison of ASTM and BS-EN Standards
ASTM BS-EN
Aggregate C 33Spec for concreteaggregates (not includinglightweight, heavyweight,and recycled aggregates)
BS-EN 12620: 2002 (SS EN 12620: 2009)(including natural, manufactured, andrecycled aggregates with density >2000kg/m3)
Admixtures C 494Spec for chemicaladmixtures
C 1017Spec for chemicaladmixtures for flowingconcrete
BS EN 934-2: 2012 (SS EN 934-2: 2009)*
Admixtures for concrete, mortar andgrout
Water C 94Spec for Ready-mixed concrete calls for
test on setting time and 7-day strength of mortar
BS EN 1008: 2002
Mixing water for concrete (including
water recovered from processes in theconcrete industry, as mixing water forconcrete
F rther Reading Optional
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Further Reading - OptionalTopic Mindess et al (2003) Neville (5thEd)
Cement Chapters 3 & 4 Chapter 1
Mineral admixtures Chapter 5 Chapter 2Chemical admixtures Chapter 8 Chapter 5
Water Chapter 6 Chapter 4
Aggregate Chapter 7 Chapter 3
Fresh concrete Chapter 9 Chapter 4
Hardened concrete- responds to stress- Time dependent deformation
Chapter 13Chapter 16
Chapter 6Chapter 9
Hardened concrete- assessment of strength Chapter 14 Chapter 12
Durability Chapter 18 Chapter 10
E- book: Mindess et al : 2003
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E- book: Mindess et al : 2003