cement chapter 7

7. Cement PerformanceProperties

C E M E N T T E C H N O L O G Y N O T E S 2 0 0 5 89

7 . 1 I N T R O D U C T I O N

7 . 2 C E M E N T P O W D E R P R O P E R T I E S

7 . 2 . 1 F I N E N E S S

7 . 2 . 2 F L O WA B I L I T Y A N D P A C K S E T

7 . 2 . 3 S H E L F L I F E A N D A I R S E T T I N G

7 . 2 . 4 C E M E N T T E M P E R A T U R E

7 . 2 . 5 C E M E N T C O L O U R

7 . 2 . 6 F R E E S I L I C A

7 . 3 C E M E N T C H E M I S T R Y

7 . 3 . 1 A L K A L I L E V E L

7 . 3 . 2 C 3 A

7 . 3 . 3 C 3 S

7 . 3 . 4 C H L O R I D E

7 . 3 . 5 M A G N E S I A A N D F R E E L I M E

7 . 3 . 6 S O 3 C O N T E N T

7 . 3 . 7 E C Z E M A

7 . 3 . 8 L E A C H A T E S

7 . 4 R H E O L O G I C A L P R O P E R T I E S

7 . 4 . 1 WA T E R D E M A N D

7 . 4 . 2 E A R LY S T I F F E N I N G

7 . 4 . 3 S L U M P L O S S

7 . 4 . 4 B L E E D I N G

7 . 5 S E T T I N G B E H AV I O U R

7 . 6 S T R E N G T H D E V E L O P M E N T

7 . 6 . 1 2 8 D AY S T R E N G T H

7 . 6 . 2 E A R LY S T R E N G T H

7 . 6 . 3 S T R E N G T H VA R I A B I L I T Y

7 . 6 . 4 P E R F O R M A N C E W I T H N O N -

C L I N K E R A D D I T I O N S

7 . 7 H E A T E V O L U T I O N

7 . 8 D U R A B I L I T Y A N D O T H E R P R O P E R T I E S

7 . 9 P E R F O R M A N C E W I T H A D M I X T U R E S

7 . 1 0 E U R O P E A N C E M E N T S T A N D A R D

7 . 1 0 . 1 I N T R O D U C T I O N

7 . 1 0 . 2 C O N S T I T U E N T S

7 . 1 0 . 3 C E M E N T T Y P E S

7 . 1 0 . 4 R E Q U I R E M E N T S

7 . 1 0 . 5 C O N F O R M I T Y

contents chapter 8


7.1 INTRODUCTIONCement properties can be assessed in many ways and for apotentially large number of characteristics, e.g. as dry cementpowder, as cement paste, in mortar, in concrete, for a range ofdurability characteristics.

Some important criteria concerning cement performance criteriaare shown in Figure 98.

The degree to which any individual characteristic is importantwill depend on:-

- the market requirements and construction activity- concrete market split, e.g. bulk ready-mixed, bulk

concrete products, bulk site use, packed site use, packed merchant use

- concrete codes, standards and rules- cement standards- cement market (competitors, market size)

Some of these criteria are briefly discussed in the followingsections.

Figure 98. Cement Performance Criteria.

7. CEMENT PERFORMANCE PROPERTIES

FinenessFlowability

Shelf Life/Air SettingPack Set

TemperatureColourAlkalis

C3AC3S

ChlorideLime ExpansionSO3 Expansion

MgO ExpansionFree Silica

Water DemandEarly Stiffening

Delayed StiffeningSlump Loss

BleedingSetting

Early Strength28 Day Strength90 Day Strength

VariabilityShrinkage

CreepFrost Resistance

Freeze-Thaw

Heat EvolutionPermeabilityCarbonation

Sulfate ResistanceCorrosion Resistance

Acid ResistanceSea water Resistance

ASRLeachates

EfflorescenceEmissions

Cr (Eczema)Performance with AdditionsPerformance with Admixtures

contents chapter 7 chapter 8


7.2 CEMENT POWDER PROPERTIES7.2.1 FINENESSAlthough there has been an increasing use of particle sizeanalysis the majority of users will specify cement fineness interms of the air permeability specific surface area (or Blaine)(See Section 3.3).

Some users require an upper limit on Blaine (e.g. State Highwayand Transport Organisation in North America, AASHTO) onaccount of concerns over shrinkage. Others, for example in theproduction of spun pipes, require a lower, but specificcontrolled fineness.

Fineness is an important factor in controlling bleeding.

In general higher fineness will:- accelerate setting times- increase early strength- produce a lighter colour- reduce bleeding- increase heat release

The majority of customers will require cement to be free of"nibs" (i.e. > 1mm size particles), hence the need for screeningafter the cement mill or removal from within milling systems.

7.2.2 FLOWABILITY AND PACK SETGood flowability characteristics can be very important,especially if cement is to be transported over large distancesand/or stored for long periods.

In most cases poor flowability is associated with pack set, i.e.the cement becomes tightly packed, exhibiting strong cohesiveforces. The packed cement then requires considerable energy toregain free flowing behaviour.

Factors which increase the likelihood of pack-set are:-- higher fineness- wider particle size distribution- presence of moisture- absence of grinding aid

It should also be noted that customer materials handlingequipment tends to become "tuned" to a particular level offlowability, and thus significant changes (either decreased orincreased flowability) can cause problems.

There are a number of methods to assess flowability, such asthose used by Grace Cement and Concrete Products.The simple determination of poured and tapped bulk densitycan often provide a useful guide. The poured density of cementwill typically be around 1000 kg/m3. However the tappeddensity will typically be 1500 - 1800 kg/m3.

The ratio between tapped and poured densities can be a guideto flow properties. Higher ratios lead to increased problems offlowability.

7.2.3 SHELF LIFE AND AIR SETTINGFlowability and pack set usually refers to the cement in normaluse. However some cements can lead to the formation of lumpsduring and after storage. This can be as a result of:-

- free moisture (e.g. silo leaks)- gypsum dehydration during storage- syngenite formation

This lump formation is often referred to as silo set.

The slow dehydration of gypsum during storage can take placewhere cement is stored at around 70C or above. If the cementhad been milled at a relatively high temperature (say 120C)then either none or only small amounts of gypsum wouldremain in the cement after the mill. In this case furtherdehydration during storage cannot take place. However wherecement is only ground at moderate temperatures (say 90-110C)and/or with a short residence time, it is possible that gypsumwill be retained in the cement after the mill. Further dehydrationduring storage can then be very important. The water releasedfrom dehydration migrates to cooler regions in the silo, usuallytowards the outer wall, where hydration can occur.

The utilisation of high efficiency separators (with open-circuitairflow) and/or cement coolers can permit a reduction intemperature to below 70C, thereby virtually eliminating thechances of further dehydration in storage.

The formation of Syngenite (K2SO4.CaSO4. H2O) can formwhere there is gypsum and potassium sulphate exposed tomoisture. This causes long needle shaped crystal growth whichresults in the formation of lumps.

In many cases the likelihood of air set tendency can be assessedin a laboratory procedure where the cement is exposed tohumidity for a period (say 3 days) and then sieved at 500 - 600microns. The percentage retained is then a measure of thepropensity for lump formation.

Air set tendency is higher for higher levels of K2O and lower forhigher levels of free lime (the latter acts as a desiccant).

Further details are shown in TIS MS016.

7.2.4 CEMENT TEMPERATUREHigh cement delivery temperatures are usually undesirable onaccount of:-

- possible injury to personnel- contribution made to overall concrete temperatures

Customer restriction of temperature has become increasinglycommon with temperatures often required below 80C or 60C.

The importance and relevance of temperature needs to beassessed in each individual market.

In contrast, high temperatures have been used as a means ofassessing cement "freshness". Also some customer processesrequire heat.




7.2.5 CEMENT COLOURCement colour can be evaluated, usually from the tristimulus y-value.

Consistency of colour is important and it may also be importantto have good colour matching to that of competitors so thatmulti sourcing of cement does not result in colour changes inmortar or concrete.

The colour is principally influenced by:-- clinker C4AF content (higher levels producing darker

colour)- cement fineness (higher levels producing lighter

colour)- non-clinker components

Fly ash tends to contain small amounts of residual carbon,which can have a marked influence on colour. Higher grindingfineness of interground fly ash cement can result in a darkercolour.

In some, less developed markets, dark colour has been linked to"strong" cement!

7.2.6 FREE SILICAFree silica is present in most cements, arising from the non-clinker components, e.g.

- gypsum source- limestone- sand- pozzolan

The principal concern is one of health and safety. There havebeen discussions of characterising materials into thosecontaining less than 1% free silica or above 1% free silica. Theterm "carcinogenic" has been linked to materials with above1% free silica.Whilst pure Portland cements (clinker and gypsum only) tend

to have low levels of free silica (usually around 0.1%, from thegypsum) filled cements can contain relatively higher levels offree silica.




7.3 CEMENT CHEMISTRY7.3.1 ALKALI LEVELCement alkali levels have become increasingly restricted as aresult of the concerns arising from alkali-aggregate reaction.

Cements can be restricted to less than 0.60 Eq Na2O, or evenless than 0.45 Eq Na2O in some cases.

Alternative approaches, to limit the alkali input in kg/m3 ofconcrete, have also been used.

7.3.2 C3AC3A level is often restricted to either provide moderate sulphateresistance (e.g. ASTM Type II maximum C3A of 8%) or highsulphate resistance (e.g. C3A maximum of 3%).

C3A may also be seen as a contributory factor for earlystiffening problems in concrete.

7.3.3 C3S Since C3S is the principal constituent of Portland cement clinkerits level is often specified with a minimum requirement.However there are instances where a maximum limit has beenimposed (60% in AASHTO - N. America State Highways andTransport Organisation).

7.3.4 CHLORIDEChloride content has long been limited on account of theadverse influence on corrosion of reinforcement. Many nationalstandards impose a limit of 0.1%.

7.3.5 MAGNESIA AND FREE LIMEThe presence of MgO can give rise to the formation of periclasecrystals under certain burning and cooling conditions. Theseresult in expansive reactions with water and thus can causefailure of structures. Most national standards limit the MgOcontent to 5 or 6%.

Expansion of cement is assessed by the Le Chatelier apparatusand/or the ASTM autoclave expansion test. The first ispredominately influenced by the presence of free lime, whilst theautoclave test also responds to MgO.

Where MgO levels are inherently high (say 4.0%) it isimportant to have relatively hard burning and quick cooling.This ensures that large periclase crystals cannot grow and that alow free lime level is achieved. The latter is important to avoidan unacceptable combined influence of free lime and MgO.

7.3.6 SO3 CONTENTThe optimum SO3 content for a given cement can be quitecomplex and will depend on the overall characteristics required,i.e. SO3 can be optimised for:-

- workability- setting- early strength- late strength

High (excessive) levels of sulphate are believed to causeexpansion as a result of delayed crystallisation ofsulphoaluminates. Accordingly, most standards impose an upperlimit on the SO3 content (e.g. EN197 - 3.5% SO3 for someclasses and 4.0% SO3 for others).

7.3.7 ECZEMASmall levels of chrome (and cobalt) are known to cause eczemain persons who are susceptible to this.

Chrome is often present in cement at around 50 - 300 g/tonne(typically 100 gram/tonne). Of this, usually 5 - 15g/tonne (say10g/tonne) is present as hexavalent chromium (CrVI), i.e. water-soluble. It is this that causes the allergic reaction dermatitis.

In Scandinavia the water soluble chrome has to be kept below2g/tonne. This can be achieved by careful raw material selection(sources of iron oxide often contain chrome), or more usuallythrough chemical reduction with ferrous sulphate (inter-groundor blended at 0.3 0.5%).

7.3.8 LEACHATESLeaching of concrete by flowing water has sometimes causedsevere damage.

Water can be expected to remove alkali hydroxides, dissolvecalcium hydroxide and decompose the hydrated silicates andaluminates. During this deterioration of the structure minorcompounds may also be leached from the concrete.

Therefore any minor, but environmentally important, elementsmay end up in the ground water. In certain situations,particularly as environmental awareness and restrictionsincrease, it maybe necessary to assess the leachates from a givenconcrete. However, in general, the levels of minor compounds(e.g. trace metals) are only at similar levels to that of naturallyoccurring materials.




7.4 RHEOLOGICAL PROPERTIES7.4.1 WATER DEMANDCement with a characteristic low water demand is oftenpreferred because of the resultant economies in concrete mixes.

However water demand is often used in a rather generalmanner, without any specific reference to paste, mortar orconcrete.

Paste water demand is essentially influenced by the physicalproperties of the cement powder, particularly the particle sizedistribution. A narrower psd results in a higher water demand.

For concrete the water demand is more strongly influenced bythe initial reactivity, e.g. C3A behaviour and role of SO3. (SeeSection 1.7).

In general, the behaviour of water demand over time is of moreimportance.

7.4.2 EARLY STIFFENINGEarly stiffening due to a false set tendency (See 1.7) can be moreof a problem where high speed, short duration mixing is used.

However early stiffening as a result of a tendency for flash setbehaviour (See 1.7) can be a more severe problem, particularlywhere admixtures are used.

Unpredictable and/or delayed stiffening behaviour can causeparticular problems.

7.4.3 SLUMP LOSSThe water demand over a period of time can be stronglyinfluenced by high ambient temperatures and/or long journeytimes for concrete delivery.

A variable slump loss behaviour, for example as a result ofinconsistent gypsum/clinker reactivity balance, is undesirable.

Concrete with a high initial water demand often provides less ofa slump loss, whilst concrete with a low initial water demandcan often show a more severe slump loss.7.4.4 BLEEDINGBleeding concerns the appearance of water on the surface ofcement, mortar or concrete. This results from the sedimentationof the solids.

Initial bleeding properties are usually desirable. A low level canoften result in cracking and finishing problems. Excessivebleeding, however, can result in finishing problems and surfacedeterioration.Bleeding should be assessed in terms of the overall bleedcapacity (total bleed water volume) and the bleed rate (bleedwater versus time).

Bleeding or the appearance of bleeding is reduced by:-- higher fineness- increased early hydration (e.g. by alkalis)- favourable weather conditions (e.g. high winds, low

humidity, high temperature)




7.5 SETTING BEHAVIOURSetting times are commonly quoted for cement pastes and alsomortar and concrete. However the setting time is ratherimprecise.

Stiffening (See 7.4) usually refers to a rapid loss of workability,usually in minutes or at least the first hour.

Hardening and strength development refers to changes wheresignificant compressive strength is obtained.

Setting generally refers to somewhere between the two, i.e. it isdevelopment of stiffening without significant compressivestrength, but more significant than that of early stiffening wherevery little compressive strength is developed.

Setting only takes place with the onset of alite hydration.

The actual setting times in cement paste are determined by thepenetration of a needle.

Therefore, the following distinctions can be made:-Stiffening: In the first minutes, usually less than 1 hour

No strength development, but significant loss of workabilityUsually involves C3A reactivity and solubility of SO3

Setting: Usually between 1 and 4 hours (Paste)No significant strength development, but no longer workableUsually involves onset of significant C3S hydration and other hydration products

Hardening: Usually after 8 hoursInvolves significant strength developmentInvolves considerable C3S hydration and other hydration products

It is therefore possible that the mechanisms involved in theseoften linked stages can be quite independent.




7.6 STRENGTH DEVELOPMENT7.6.1 28 DAY STRENGTHThe 28-day strength, either of mortar or concrete, is often seenas the most important parameter, although this should only beassessed in conjunction with other performance criteria, such aswater demand and slump characteristics.

A target 28-day strength is essential in order to meet standardrequirements and customer expectations. The cement producernormally assesses this for a standard mortar (e.g. EN196, ASTM).

Sometimes an intermediate strength, for example at 7 days, canbe important as a target requirement. The 7 to 28 daydevelopment then becomes important.

Later age strengths, e.g. 90 days, are also on occasion,important, for example in large civil engineering constructions.

The principal cement properties which enhance the 28-daystrength are:-

- higher SSA- lower residue (e.g. at 45 or 30 microns)- higher silicates- smaller crystal (e.g. alite) sizes- lower alkali level- lower level of pre-hydration (i.e. lower LOI)- optimum SO3 content (difficult to quantify)- usually higher clinker content

7.6.2 EARLY STRENGTHSome customers, e.g. concrete product manufacturers, dependon the strength development over the first few hours, or morecommonly, overnight. Whilst the 2-day strength is often arequirement of the standard, a 1-day strength can be morerelevant. In some instances knowledge of strength developmentat 16 hours, or even 8 hours, may also be important.

To provide a broad range of targets for a wide range ofcustomer markets a requirement for a minimum 1-day strengthis becoming increasingly essential.

As a result of largely controlled maximum 28-day strengths,which can be achieved with either lower fineness and/or non-clinker components, the need for good early strength is oftenbecoming more important.The early strength development is increased by:-

- higher cement fineness- higher alkali level (more specifically by a higher water

soluble alkali level (See TIS MS004) and thus a higherclinker SO3 level)

- higher C3S to C2S ratio (i.e. higher LSF)- usually a higher SO3 content- usually a high clinker content- smaller crystal sizes- lower level of pre-hydration (low LOI)

7.6.3 STRENGTH VARIABILITYAt face value specifications and standards may appear to permita relatively wide range of cement properties, including strength.However, as a result of customer needs and indirect economicbenefits in production, there is a need to target low levels ofvariability.

Good consistency is in fact often seen to be more importantthan actual strength level.

7.6.4 PERFORMANCE WITH NON-CLINKER COMPONENTS

Besides the non-clinker components utilised in the production ofcement, a wide range of additions can be used at the concretemixer. Hence the reactivity of a particular cement with theseadditions can become a relevant market factor for the cement.Knowledge of the use of additions by the cement customer istherefore desirable. Additions can include:-

- slag- fly ash- natural and industrial pozzolans- silica fume- limestone- calcined shale

It may then be important to assess the cement reactivity withthese materials. For example, a higher alkali content maybecome beneficial.




7.7 HEAT EVOLUTIONWhen cement reacts with water heat is evolved and this can bemonitored with a conduction calorimeter.

An example of the heat liberation rate for a normal PortlandCement is shown in Figure 99.

Calorimetry in general is a useful tool for illustrating thekinetics of cement hydration, as any chemical activity isassociated with heat exchange. Figure 99 shows an example ofhydrating cement paste in an isothermal calorimeter. The termisothermal denotes that the sample is kept at practicallyconstant temperature. Any retardation effects become veryapparent and cement admixture interactions affecting thekinetics of hydration can be studied in detail as shown in thefollowing examples. Note that all calorimetry samples wereprepared as externally mixed cement paste. While externalmixing leads to non-isothermal condition during the first 10-15minutes after loading samples in the calorimeter, externalmixing provides for more intensive, concrete-like mixing ascompared to true isothermal samples based on water injection.As a consequence, the heat evolution in externally mixedsamples is not quantitative during the first 10-15 minutes afterloading samples in the calorimeter.

Figure 99. Heat Evolution Curve.

The first peak (A) is the highest, but of short duration, and isattributed to exothermic wetting and early stage reactionsinvolving the formation of ettringite (i.e. reaction between C3Aand SO3). Sometimes the rehydration of hemihydrate togypsum may also contribute. This is followed by the so-calleddormant period (B) where heat evolution is very low, indicatingslow and well-controlled aluminate hydration. Stiffnessgradually increases and workability is generally lost during thisperiod. The main heat peak (C) corresponds to the middle stagereactions, during which setting occurs. These principally involvethe formation of tricalcium silicate hydrates and lime. Asecondary aluminate hydration peak (D) sometimes associatedwith sulfate depletion and conversion from Ettringite toMonosulfate. Past work has indicated general correlation ofconcrete initial setting time with the point at which poweroutput reaches 1.0-1.5 mW/g dry cement, depending on w/cratio and cement type. In this figure 1.5 mW/g has been used asan indication of set time. A further, but less distinct, shoulder isalso sometimes seen and associated with the hydration of theferrite phase or the conversion of ettringite tomonosulphoaluminate.

Heat evolution can be very important when considering cementand concrete design for large structures of low surface tovolume ratios. High heat evolution can result in undesirabletemperature gradients and resultant possible cracking.

Heat evolution characteristics can be quite complex, with manyfactors involved. However the amount of heat evolved at agiven time is directly related to the amounts of the clinkerphases that have reacted.

This will depend on the majority of the cements chemical andphysical properties as well as curing conditions.




7.8 DURABILITY AND OTHER PROPERTIESThe preceding criteria are generally the most important whenevaluating the fitness of cement for its market. These mainlyconcerned:-

- cement powder properties- cement chemistry- water demand and workability- setting- strength development- heat evolution

However there are other performance criteria that can beimportant in specific cases or when assessing the longer-termperformance.

Efflorescence is the term given to crystalline or powderydeposits (usually white) which form on the surface of products,like concrete, precast concrete, blocks and bricks. Primaryefflorescence occurs at the time when the product is in thesaturated state to when it is dry. Secondary efflorescenceconcerns later stages, for example when the product is re-wetted. The efflorescence can be salts (carbonates, sulphates orchlorides) of calcium, sodium and potassium. In Portlandcement efflorescence is usually as a result of calcium carbonateresulting from the reaction of atmospheric CO2 with calciumhydroxide released from cement hydration.

Dimensional changes, for example due to drying shrinkage orcreep under load, can be very important and may lead tocracking.

Protection of reinforcing can be adversely influenced bypermeability and carbonation These can also result in a reducedresistance to sulphates, acids, sea water and frost attack.




7.9 PERFORMANCE WITH ADMIXTURESPerformance of admixtures is not considered here, butadmixtures are used to influence many properties, such as:-

- water demand- slump retention- setting- early strength- later strength- durability

However, it is known that cements interact with admixtures inan often varied and unpredictable manner. The so-calledcement-admixture incompatibility has often been discussed.

Cement-admixture performance can be expected to beprincipally influenced by the same parameters that influencewater demand, workability, slump loss and early stiffening, i.e. :-

- C3A reactivity (C3A level, alkali/sulphate balance)- cement fineness- surface freshness (prehydration)- crystallography- availability of soluble SO3

(See Section 1.7)

If anything, cements which show a false-set behaviour in theabsence of admixtures often perform better with admixturesthan without.

In contrast, cements that have a tendency for flash set behaviouroften lead to significant problems with admixtures, such asrapid stiffening and loss of workability (i.e. cement-admixtureincompatibility).The mechanisms involved are not fully understood, but involve:-

- depression of sulphate solubility (especially with lignosulphonate)

- absorption of admixture by hydration products

With the increasing use of admixtures, good performance ofcement with admixtures is increasingly important. If cements areknown to be problematical with admixtures then theirmarketability becomes lessened.




7.10 EUROPEAN CEMENT STANDARD7.10.1 INTRODUCTIONThe standard, EN197, was initiated in 1969 by the EEC andpassed to CEN in 1973. The initial enquiries identified some 20different cement types in 1975, which became 50 different typesby 1990.The cements originated from:-

- different raw materials- different climatic conditions- different social/cultural attitudes

These resulted in typical architectural and building techniquesand various national standards.

EN197-1 principally considers cements where hardening mainlydepends on the hydration of calcium silicate and where they areprovided for common use. It specifies:-

- constituents- mechanical requirements- physical requirements- chemical requirements- rules for conformity

The requirements are based on tests according to EN196.

The current standard is EN 197-1:2000 and this was adoptedwithin the European Construction Products Directive in 2000.

7.10.2 CONSTITUENTSMain Constituents, Section 5.2Clinker (5.2.1): hydraulic

66.6% calcium silicatesCaO/SiO2 2.0MgO 5.0%

Slag (5.2.2): Latent hydraulic 66.6% Glassy 66.6% of CaO + MgO + SiO2(CaO + MgO)/SiO2 > 1.0

Pozzolan (5.2.3): Natural or IndustrialReactive SiO2 and Al2O3Reactive CaO is negligibleReactive SiO2 25%

Fly Ash (5.2.4): Silico-aluminous or silico-calcareousLOI 5.0%*Siliceous:-Pozzolanic

Reactive CaO < 10.0%Free CaO ,1.0% (or 5.0%) LOI 4.0%

BET SSA 15m2/g

Minor Additional Constituents, Section 5.3Improve cement physical propertiesInert or hydraulic or pozzolanicShall not increase the water demandShall not impair the resistance to deterioration in any wayShall not reduce the corrosion protection

Calcium Sulphate, Section 5.4Can be gypsum, hemihydrate, anhydrite or any mixtureNatural or by-product

Additives, Section 5.5:(See Figure 100)

Figure 100. EN 197-1:2000, Section 5.5

7.10.3 CEMENT TYPESThe cement types covered by EN197 are:-

- CEM I Portland cement- CEM II Portland-composite cement- CEM III Blastfurnace cement- CEM IV Pozzolanic cement- CEM V Composite cement

Details of these are shown in Figure 101.

7.10.4 REQUIREMENTSRequirements exist for:-

- compressive strength- setting- expansion- chemistry - LOI

- IR- SO3- Cl- Pozzolanicity

Details are shown in Figures 102 and 103.


Additives for the purpose of EN 197-1 not covered in 5.2 to 5.4 which areadded to improve the manufacture or the properties of the cement.

The total quantity of additives shall not exceed 1,0 % by mass of thecement (except for pigments). The quantity of organic additives on a drybasis shall not exceed 0,5 % by mass of cement.

These additives shall not promote corrosion of the reinforcement or impair theproperties of the cement or of the concrete or mortar made from the cement.

When admixtures for concrete, mortar or grouts conforming to the EN 934series are used in cement the standard notation of the admixture shall bedeclared on bags or delivery documents.


C E M E N T T E C H N O L O G Y N O T E S 2 0 0 5 1017. CEMENT PERFORMANCE PROPERTIES

MainTypes

Notation of the 27 products (types ofcommon cement)

Main Components (as a percentage of the total mass)a MinorAdditionalConstituents

Clinker (K) Blast furnaceSlag (S)

Silica Fume(Db)

NaturalPozzolan (P)

CalcinedPozzolan (Q)

Silica Fly Ash(V)

Calcareus FlyAsh (W)

Burnt Shale (T) Limestone (L) Limestone (LL)

CEM I Portland Cement CEM I 95 - 100 - - - - - - - - - 0 - 5

CEM II Portland-SlagCement

CEM II/A-S 80 - 94 6 - 20 - - - - - - - - 0 - 5

CEM II/B-S 65 - 79 21 - 35 - - - - - - - - 0 - 5

Portland-SilicaFume Cement

CEM II/A-D 90 - 94 - 6 - 10 - - - - - - - 0 - 5

Portland-Pozzolan Cement

CEM II/A-P 80 - 94 - - 6 - 20 - - - - - - 0 - 5

CEM II/B-P 65 - 79 - - 21 - 35 - - - - - - 0 - 5

CEM II/A-Q 80 - 94 - - - 6 - 20 0 0 - - - 0 - 5

CEM II/B-Q 65 - 79 - - - 21 - 35 0 0 - - - 0 - 5

Portland-Fly AshCement

CEM II/A-V 80 - 94 - - - - 6 - 20 0 - - - 0 - 5

CEM II/B-V 85 - 79 - - - - 21 - 35 0 - - - 0 - 5

CEM II/A-W 80 - 94 - - - - - 6 - 20 - - - 0 - 5

CEM II/B-W 65 - 79 - - - - - 21 - 35 - - - 0 - 5

Portland-BurntShale Cement

CEM II/A-T 80 - 94 - - - - - - 6 - 20 - - 0 - 5

CEM II/B-T 85 - 79 - - - - - - 21 - 35 - - 0 - 5

Portland-LimestoneCement

CEM II/A-L 80 - 94 - - - - - - - 6 - 20 - 0 - 5

CEM II/B-L 65 - 79 - - - - - - - 21 - 35 - 0 - 5

CEM II/A-LL 80 - 94 - - - - - - - - 6 - 20 0 - 5

CEM II/B-LL 65 - 79 - - - - - - - - 21 - 35 0 - 5

PortlandCompositeCement c

CEM II/A-M 80 - 94 6-20 0 - 5

CEM II/B-M 65 - 79 21-35 0 - 5

CEM III Blast FurnaceCement

CEM III/A 35 - 64 36 - 85 - - - - - - - - 0 - 5

CEM III/B 20 - 34 68 - 80 - - - - - - - - 0 - 5

CEM III/C 5 - 19 81 - 95 - - - - - - - - 0 - 5

CEM IV PozzolanicCement c

CEM IV/A 65 - 89 - 11 35 - - - 0 - 5

CEM IV/B 45 - 64 - 36 - 55 - - - 0 - 5

CEM V CompositeCement c

CEM V/A 40 - 64 18 - 30 - 18 - 30 - - - - 0 - 5

CEM V/B 20 - 38 31 - 50 - 31 - 50 - - - - 0 - 5

Figure 101. EN197-1:2000. The27 products in the family ofcommon Cements.

a) The values in the table refer to the sum of the main and minor additional constituents

b) The proportion of silica fume is limited to 10%

c) In Portland-composite cements CEM II/A-M and CEM II/B-M, in Pozzolanic cements CEM IV/A and CEM IV/B and in composite cements CEM V/A and CEM V/B the main constituents other than clinker shall be declared by designation of the cement .



Figure 102. EN 197-1:2000 Table 2. Mechanical and PhysicalRequirements

Figure 103. EN 197-1:2000 Table 3. Chemical Requirements

a) Requirements are given as percentage by mass of the final cement.b) Determination of residue insoluble in hydrochloric acid and sodiumcarbonate.c) Cement type CEM II/B-T may contain up to 4,5% sulfate for allstrength classes.d) Cement type CEM III/C may contain up to 4,5% sulfate.e) Cement type CEM III may contain more than 0,10% chloride but inthat case the maximum chloride content shall be stated on thepackaging and/or the delivery note.f) For pre-stressing applications cements may be produced according toa lower requirement. If so, the value of 0,10% shall be replaced by thislower value which shall be stated in the delivery note.

7.10.5 CONFORMITYThe criteria for conformity address:-

- definition of the requirement in terms of a characteristic value

- the acceptable percentage of defects- the probability of acceptance- the absence of major defects

In EN197-1:2000 the procedures for monitoring conformity tothe standard involve:-

- continuous assessment- a system of producers statistical process control

referred to as Autocontrol- audit testing by a third party if required by National

or International standards- random spot sampling- utilisation of acceptability constant

Conformity allows a certain percentage of defects, i.e.- lower strength limit - 5%- lower strength limit - 10%- physical and chemical - 10%

To ensure conformity with the above percentages, anacceptability constant, kA, is used which depends on thenumber of test results (See Figure 104).Conformity is then verified by:-

mean constant kA* s.d. lower limitmean constant kA* s.d. upper limit

Where s.d. is the standard deviation of the autocontrol testresults in the test period.

Conformity example, for 28-day mortar strength:Target mean strength = ??Standard deviation = 2.4Number of tests, n = 50Upper Limit = 62.5Conformity Parameter, Pk = 10% (from Figure 104)Acceptability Constant, kA = 1.65 (from Figure 104)

Therefore: mean upper limit + constant kA* s.d.mean 62.5 + 1.65* 2.4mean 58.54


StrengthClass

Compressive Strength MPa InitialSetting

Time min

Soundness(expansion)

mmEarly Strength Standard Strength

2-days 7-days 28-days

32,5N - 16,032,5 52.5 75

10

32,5R 10,0 -

42,5N 10,0 -42,5 62.5 60

42,5R 20,0 -

52,5N 20,0 -52,5 - 45

52,5R 30,0 -

1 2 3 4 5

Property Test Reference Cement Type Strength Class Requirementsa

Loss onIgnition EN 196-2

CEM ICEM III all 5,0%

InsolubleResidue EN 196-2

b CEM ICEM III all 5,0%

SulfateContent (as SO3)

EN 196-2

CEM ICEM IIc

CEM IVCEM V

32,5 N32,5 R42,5 N

3,5%

42,5 R52,5 N52,5 R 4,0%

CEM IIId all

ChlorideContent EN 196 -21 all

e all 0.10%f

Pozzolanicity EN 196-5 CEM IV all Satisfies thetest



Figure 104. EN 197-1:2000, Table 6. Acceptability Constant kA.

Note: values given in this table are valid for CR = 5%.a) values of kA valid for intermediate values of n may also be used.

EN197-1:2000 also specifies individual limits for major defects, i.e.

- 2.5MPa for 28-day strength lower limit- 2.0MPa for 2-day strength lower limit- 15 minutes for class 32.5 initial set time- 15 minutes for class 42.5 initial set time- 5 minutes for class 52.5 initial set time10mm for soundness+ 0.5% for SO3 limits0.10% for chloride


Number of testresults n

kAa

for Pk = 5% for Pk = 10%

(early and standardstrength, lower limit) (other properties)

20 to 2122 to 2324 to 2526 to 2728 to 2930 to 3435 to 3940 to 4445 to 4950 to 5960 to 6970 to 7980 to 8990 to 99100 to 149150 to 199200 to 299300 to 399> 400

2,402,352,312,272,242,222,172,132,092,072,021,991,971,941,931,871,841,801,78

1,931,891,851,821,801,781,731,701,671,651,611,581,561,541,531,481,451,421,40


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