Cement Standards Updated.doc

Table of Contents 1. INTRODUCTION.................................................................................... 1 1.1

Why are standards established ?.........................................................................2

1.2

Who established standards ?...............................................................................2

1.3

What is specified ?.............................................................................................2

2. STANDARD METHODS......................................................................3

3.

2.1

Sampling............................................................................................................3

2.2

Testing :.............................................................................................................7

Standard Specifications......................................................................15

CEMENT STANDARDS TESTING METHODS & SPECIFICATIONS

1.

INTRODUCTION The requirements on composition and performance of cement are outlined in the cement standards. The standards are established considering the actual state of knowledge and are constantly revised. If only the performance is specified, products of different compositions can be admitted. Thus, improvements and replacements by new products are promoted. Very often, it is difficult or impossible to measure the practical performance in a laboratory. Sometimes, expensive apparatus and highly skilled people are required. In such cases, instead of the performance, the composition of a product may be specified. This, however, does not allow an improvement of the product without a change of the standards.

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1.1

Why are standards established ? To assure the consumer of a market-conform and well defined quality; To protect the producer against unserious competition.

1.2

Who established standards ?

Standards are a common elaborate of : - producer

-

seller

- testing institute

-

government

-

consumer

The standards are published by a society or by the government

1.3

What is specified ?

In general, the standards comprise test methods, definitions, recommended practices, classifications and specifications. - The methods of testing (standard methods) covers sampling and describes the subsequent testing procedure used to determine the composition or performance of the material to be specified. - The requirements (standard specifications) is a precise statement of a set of requirements to be satisfied by a material, product, system or service.

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2.

STANDARD METHODS

2.1

Sampling

Without a sample there can be no analysis! Without a suitable sample there should be no analysis! Testing involves a series of activities such as sampling, sample handling and preparation, the actual measuring itself and finally data processing. The reliability of such a chain of procedures depends, of course, on the weakest link as the overall random error of testing is estimated from the sum of variances of each individual step. It is evident that sampling must be considered a very crucial step in testing. This holds particularly true when one considers that information obtained from a few grams of material is extrapolated to quantities of several tons. The frequent occurrence of all sorts of considerable errors-systematic as well as random errors - call for an adequate planning of sampling (procedures and techniques on the basis of fundamental principles). The following criteria have to be established for the design of an acceptable sampling 0

Determination of the basic material quantity (e.g. mixing bed, silo volume, lot of sold cement, etc. )

ㄱ Estimation

of the minimum size for each individual sample (guideline : approx. 1kg

for raw meal; for coarse material 30 - 40 times weight of largest grain, but at least 5 kg) ㄴ

Variability of material to be sampled (estimation of standard deviation by

experiment) and from this the sampling interval.

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Definition of the desired overall sampling accuracy with respect to sampling place and technique a differentiation must be made between: ㄷ

Sampling stationary material (static sampling):Static sampling typical cases of which are field sampling for prospecting of raw material deposits, and sampling of bag and bulk cement for quality control.

Field sampling techniques are mainly : ㄹ

Spot and chip sampling

ㅁ

Channel, trench and pit sampling

ㅂ

Dust drilling

Special procedures are required to establish representative samples from trucks, piles, etc. ㅅ

Sampling a material stream (dynamic sampling):For production and process control, dynamic sampling is always recommended (only exceptions : control of raw materials through dust from blast holes and samples from slurry basins).

Sampling for production and process control comprises : ㅇ

Coarse - grained material (gravel samples)

ㅈ

Raw meal and cement

ㅊ

Slurry, fuel, water, gas

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There are numerous types of automatic sampling systems, the following factors have to be taken into consideration : ㅋ

Material characteristics (grain size distribution, consistency, humidity, stickness,

etc.) ㅌ

Sampling site (to avoid systematic errors due to segregation, sampling of

particular material stream, etc.; particularly suitable are transfer points in the material transport system). ㅍ

Sampling conditions (size of material flow, local gas pressure, material

temperature, direction and type of material flow, simplicity of control.1 ㅎ

Sampling frequency (type and size of material variability, purpose of sampling).

ㄱ

Reliability and simplicity of sampler.

Generally, sampling for quality control of bag or bulk cement is clearly defined by standard specifications with respect to procedure and equipment (e.g. ASTM C 183, see Fig. 1 a & b).

Fig. 1a

Fig. 1 b

:

Slotted tube sampler for bulk cement

Tube sampler for packed cement

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Fig. (2) represents a simple but efficient piece of equipment for manual sample splitting of coarse and fine material that is essential for each laboratory.

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2.2

Testing :

Requirements on testing procedures and equipment differ in the cement industry according to the area of material technological testing. For discussion of choice and particularities of methods and instruments for chemical and physical testing, it is convenient to differentiate between : ㄴ Material

testing for production control

ㄷ

Quality control with respect to cement application

ㄹ

Material technological investigations in connection with project planning, special

problems in manufacture and application, research and development. Chemical analysis Chemical analysis is the most important testing activity in production control. No other testing method has undergone a similarly rapid and drastic change over recent years. Only 10 to 15 years ago, nearly all chemical laboratories in the cement industry were relying on metric and volumetric methods of analysis. A variety of analytical procedures, mainly based on physico-chemical methods, have been developed and successfully applied in cement plants : ㅁ

Complexometric and colorimetric methods

ㅂ

Absorption spectroscopy

ㅅ

X-ray fluorescence spectroscopy

ㅇ

X-ray diffraction

ㅈ

Special methods for the analysis of non-metallic elements

(e.g. C,F, S).

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Table (1) compares the principle methods with respect to their applicability, time consumption, price of instrumentation and required qualification of the operating personnel. A comparison of the analytical precision of the principal methods for clinker is indicated in Fig. 3. Table 1 Methods of Chemical Control

CRITERIA Method

Titration Gravimetry,

Investment VERY LITTLE LITTLE

Colorimetry AAS

Times of

Personnel

 of carbonates Main elements,

Analysis Minutes Many hours

Few , Trained Several ,

LS,SR,AR;

Volumetry Complexometry

Information

,,

~$10 000

BOGUE CaO, AL2O3,

Trained Approx.2-3 hrs

Fe2O3 , MgO ~$30,,000

All elements

Trained Approx.2-3 hrs

except

XRF

,,

~$250 000

S,Cl, F,P All elements +complete automation (Off-or On- line)

Several , Several , Specialist

Minutes

Few+ Specialist

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Fig 3: Standard deviation in clinker analysis From this it is evident that x-ray fluorescence (XRF) is by far the fastest and most versatile method of analysis with good precision for all types of samples tested in the cement industry. In spite of the high investment costs, this method has found wide application not only in central but also in plant laboratories, mainly because of its speed of analysis and simplicity of sample preparation. Another favourable feature of XRF is the fact that the systems can be fully automated including sample preparation. This automation made it possible to close the loop for on-line control of raw mill and silo systems. The new generation of multi- channel spectrometers offers extremely high sensitivity even for the lightest elements by improved geometry and electronics. The software available has reached a very high level of sophistication. Emission spectroscopy with plasma excitation for multi-element offers the advantage of very rapid measurement of a large number of emission lines, it has the same disadvantage as atomic absorption spectroscopy (AAS) : the material has to be dissolved before it is analyzed, which is still a time consuming step in sample preparation, particularly for noncalcined materials which have to be fused prior to dissolution.

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As a non-expensive back-up for XRF, complexometric analysis on the basis of instrumental colorimetry is propagated. A standard procedure has been developed, allowing to analyze not only clinker and cement, but also raw materials and raw meal on the 4 main elements plus magnesium within 2 to 3 hours with satisfactory precision.

Fig 4: Compilation of physical tests Test procedures for control of physical cement characteristics, such as setting behaviour, strength development, etc. are specified to the last detail by the standards. The various types of standards (e.g. BS, ASTM, Din, etc.) make it very difficult or impossible to compare results obtained by different testing procedures. Also repeatability and reproducibility of testing vary from one standard to another. There is an attempt to establish international standards (e.g. ISO). A compilation of the physical tests according to ASTM as an example is schematically illustrated in Fig. (4).

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Particularly where cement manufacturers have to meet stringent quality requirements e.g. in a highly competitive market - efforts are often made to control the quality of the final product at the earliest possible stage of the process and to apply accelerated test methods. This applies especially to the strength development characteristics; many attempts have been made to correlate early strength (e.g. after 24 hrs) with late strength after 7 or 28 days; acceleration by increased temperature (Cric method) shall provide information on late strength after only few hours. The most recent effort even claims that it is possible to predict the 28 day strength with ultimate precision judging from the microscopic appearance of the main clinker minerals alite and belite (Ono method). Meanwhile, it has, however, been proven that the recommended rapid test procedure for routine diagnosis entirely lacks sound statistical principles and can, therefore, not at all serve as a substitute for physical mortar testing. Regardless of the method of analysis and the physical testing procedures applied in quality assurance, each testing laboratory must be aware of : - The size of random errors for the individual testing procedures; they are determined by systematic experiments - Type and size of systematic errors between different operators within the laboratory (to be evaluated by within - lab - experiments) and of the laboratory in comparison to other testing organizations (by experiment between laboratories). This is a prerequisite for the optimization of testing procedures and for establishing reasonable control limits for quality assurance. Moreover, it is an essential requirement for the cement manufacturer to ensure that standard specifications for testing procedures are still realistic.

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In addition to the basic test methods for routine control, a large variety of sophisticated methods and procedures is applied for material technological investigations in connection with special manufacturing and application problems and in research and development. Characterization of raw materials, clinker, additives, etc. is only limited to chemical analysis, but also the mineralogical and textural features are important. Some of them are also used in a number of plant laboratories for routine quality control, such as x-ray diffraction, to monitor the quartz and clay minerals of raw materials and to examine free lime in clinker; or differential thermal analysis to control the dehydration of gypsum in cement during the grinding process. However, if these specialized testing procedures are promoted too much, there is the danger that they might finally be included in the standard specifications. This has to be avoided because it would make the quality control procedures too sophisticated and expensive for the majority of plants.

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A comparison of testing methods for the physical properties of cement is shown in Table (2).

Table (2)

Testing methods

Physical Properties of Portland Cements ASTM

BS

ES

NF

EN

Sieve analysis Specific surface :-

-

-

-

-

-

Turbidimeter test

x

-

-

-

-

Air permeability Soundness :-

x

-

-

-

-

LeChatelier expansion

-

x

x

x

x

Autoclave Setting time :-

x

-

-

-

-

Fineness :-

Vicat test

x

x

x

x

x

Gillmore test

x

-

-

-

-

False set test Heat of hydration :-

x

-

-

-

-

x

x

x

-

-

x

-

-

-

-

x

x

x

x

x

x

-

-

-

-

Heat of solution method Sulphate resistance :Sulphate expansion test (Mortar) Compressive strength:(Mortar test) Air content :Mortar test x = specified

- = not specified

The mentioned trends in the development of standards are evident from these data. Moreover, it can be sent that in France and European standard the fineness is not

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specified and that only the soundness, setting time and strength are specified by all of the 5 standards considered. With different testing methods for compressive strength (table 3) significantly varying strength values are obtained with the same cement.

Table (3) Testing Methods (Compressive strength of mortar) Designation

EN 196-1

ASTM

ES

NF

ISO 679

C-109-90

2421 – Part 7

C/S ratio W/C ratio Sand, grading

1/3 0.5

1/2.75 0.485

1/3 0.5

1/3 0.5

(mm)

~0.08-2.00

~0.15-0.6

~0.08-2.00

~0.1-2.0

composition Specimen size

silica 40x40x160

quartz(Ottawa) cube 50

silica 40 x 40 x 160

silica 40x40x160

jolting table

tamping by

jolting table

jolting table

Compression

hand Compression

Compression

Compression on

on half prism

on half prism

half prism

broken by

broken by

broken by

flexural test

flexural test

flexural test

(mm) Mode of complication Nature of stress

Concluding : the strength determined according to one particular standard method cannot be converted with sufficient accuracy to the strength value according to an other standard method. For evaluation of a cement according to a particular standard specification, the corresponding standard testing method has to be used.

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The problem of International Standardization lies mainly in strength test. National standards work with different standard mortars (different water/cement ratio, different sand quality) with different sizes of the specimens and with different execution of the manual work. To avoid this problem, the EN 196 - 1 test method for strength is applied.

3.

STANDARD SPECIFICATIONS

During the last 100 years, the testing methods have been improved. Specifications in accordance with the requirements of the building practice have become more stringent and the number of parameters specified has increased. Initially, one type of cement was specified, but today each country accepts several types of cement. World trends in cement standards are shown in Table (4) Table (4) World trends in cement standards

Object number of standard cements additives to cement

Situation in the past small number

Situation in the present increasing number of

not permitted for OPC

special cements admitted for OPC with or without special

strength

tensile strength

designation flexural strength

flexural strength

compressive strength

compressive strength compressive strength minimum strength

min. & max. strength

(1)

(range)

age of tests (2) setting time

3 and 28 days initial and final

2 and 28 days initial

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Remarks on Table (4) : 1) Strength During the last 100 years, the compressive strength requirements have increased considerably. Since there is a demand for better uniformity among the cements, either coming from different plants or from the same plant, the minimum as well as the maximum 28-day strength is specified by more and more countries. 2) Age of tests At today’s progress in building techniques and precasting, the cement consumer is not only interested in the 28-day strength, but also in the early strength. The specified physical properties and chemical composition of various types of cement are compiled in tables 5,6,7.

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Table (5) Egyptian Standards Specification Strength Class Fineness Surface Area m2/Kg Soundness Le Chatelier Mm(max) Setting Time Initial minutes (min) Compressive Strength N/mm2 minimum 2d 7d 28d Chemical Properties Loss on ignition % (max) Insoluble residue % (max) Sulphate % max (Expressed as SO3) Chloride % (max) Magnesium Oxide % (max)

32.5 N

32.5 R

42.5 N

42.5 R

52.5 N

52.5 R

45

45

20

30

52.5

52.5

Not specified

10

75

60

10 10 20 16 32.5 32.5 42.5 42.5 52.5 (max) 52.5 (max) 62.5 (max) 62.5 (max)

5.0

5.0

3.5

4.0

0.10

5.00 (for the clinker)

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Table (6) British Standards Specification Strength Class Fineness Surface Area m2/Kg Soundness Le Chatelier Mm(max) Setting Time Initial minutes (min) Compressive Strength N/mm2 minimum 2d 7d 28d Chemical Properties Loss on ignition % (max) Insoluble residue % (max) Sulphate % max (Expressed as SO3) Chloride % (max) Magnesium Oxide % (max)

32.5 N

32.5 R

42.5 N

42.5 R

52.5 N

52.5 R

45

45

20

30

52.5

52.5

Not specified

10

75

60

10 10 20 16 32.5 32.5 42.5 42.5 52.5 (max) 52.5 (max) 62.5 (max) 62.5 (max)

5.0

5.0

3.5

4.0

0.10

5.00 (for the clinker)

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Table 7 American Standard Specification Type of Cement Fineness m2/kg

I O.P

II MS/MH

280

III RH

-

Soundness Autoclave mm (max)

IV LH

V SR

280

IS BLF

IP POZ

Slag % 25-70 -

Pozzolana % 15-40 -

0.8

0.5

Compressive Strength N/mm2 (min) 1d 3d 7d 28d

12 19 -

10 16 -

Setting Time Initial minutes (min) final hours (max)

NaO equiv. Na2O + 0.658 K2O max.

7 17

12.4 19.3 24.1

6.25

3.0

Insoluble Residue % (max.)

Magnesium Oxide % (max)

8 15 21

12.4 19.3 24.1

45

Chemical Properties Loss on Ignition % (max.)

Sulphate % (max)

12 24

7.0

2.5

3.0

0.75 3.0 C3A ≤ 8 3.5 C3A > 8

3.0 C 3A ≤ 8

3.5 C3A ≤ 8 4.5 C3A > 8

2.3 C 3A ≤ 8

2.3 C 3A ≤ 8

6.0

0.60 For low alkali type

3.0

5

1.0

-

3.0

4.0

-

5.0

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Presently, there are two principal types of cement standards : ASTM EN

( based mainly on DIN and AFNOR )

These standards are the backbone of most other national standards . Most Latin American countries use ASTM. The EN has recently become popular , not only in Europe, but also in other continents, as it displaced the national standards in Europe. The following standard testing methods have now been established : EN 196

- Methods of testing cement

EN 196-1

- Determination of strength

EN 196-2

- Chemical analysis of cement

EN 196-3

- Determination of setting time and soundness

EN 196-4

- Quantitative determination of constituents

EN 196-5

- Pozzolanicity test for pozzolanic cements

EN 196-7

- Methods of taking and preparing samples of cement

EN 196-21

- Determination of the chloride, carbon dioxide and alkali content of cement

ENV 197-1

- Cement composition, specifications and conformity criteria Part 1 : Common cement

The main features of the EN specification standard are compiled in table 8 (composition and classification ) , table 9 (requirements for the chemical properties ) , and table 10 (requirements for the mechanical and physical properties ).

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Table 8 EN Cement Type and Composition Main types

Notation of the 27 products (types of common cement

Clinker

Blastfurnace slag

Composition [percentage by mass a)] Pozzolana Fly ash

Silica fume

natural

CEM I CEM II

Portland cement Portlandslag cement Portlandsilica fume cement Portlandpozzolana cement Portlandfly ash cement Portlandburnt shale cement Portlandlimestone cement

CEM I

K 95-100

S 6 to 20 21 to 35

Burnt Shale

Limestone

Minor additional constituents

Db) -

P -

natural calcine d Q -

Siliceous

calcareou s

V -

W -

T -

L -

LL -

0 to 5

-

-

-

-

-

-

-

-

0 to 5 0 to 5

-

-

-

-

-

-

-

0 to 5

6 to 20 21 to 35 -

6 to 20 21 to 35 -

6 to 20 21 to 35

-

-

0 to 5 0 to 5 0 to 5 0 to 5 0 to 5 0 to 5 0 to 5 0 to 5 0 to 5 0 to 5

-

0 to 5

-

0 to 5

6 to 20 21 to 35

0 to 5

CEM II/A-S CEM II/B-S

80 to 94 65 to 79

CEM II/A-D

90 to 94

-

6 to 10

CEM II/A-P CEM II/B-P CEM II/A-Q CEM II/B-Q CEM II/A-V CEM II/B-V CEM II/A-W CEM II/B-W CEM II/A-T CEM II/B-T

80 to 94 65 to 79 80 to 94 65 to 79 80 to 94 65 to 79 80 to 94 65 to 79 80 to 94 65 to 79

-

-

CEM II/A-L

80 to 94

-

-

-

-

-

-

-

CEM II/B-L

65 to 79

-

-

-

-

-

-

-

CEM II/A-LL

80 to 94

-

-

-

-

-

-

-

6 to 20 21 to 35 -

CEM II/B-LL

65 to 79

-

-

-

-

-

-

-

-

6 to 20 21 to 35 -

6 to 20 21 to 35 -

0 to 5

PortlandCEM II/A-M 80 to 94 6 to 20 0 to 5 composite CEM II/B-M 65 to 79 21 to 35 0 to 5 c) cement CEM Blast CEM III/A 35 to 64 36 to 65 0 to 5 III furnace CEM III/B 20 to 34 66 to 80 0 to 5 cement CEM III/C 5 to 19 81 to 95 0 to 5 CEM Pozzolani CEM IV/A 65 to 89 11 to 35 0 to 5 IV c cement c) CEM IV/B 45 to 64 36 to 55 0 to 5 CEM Composite CEM V/A 40 to 64 18 to 30 18 to 30 0 to 5 V cement c) CEM V/B 20 to 38 31 to 50 31 to 50 0 to 5 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, CEM II/B-M, Pozzolanic cements CEM IV/A, 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

ACMC Cement Standards, Testing Methods & Specifications 22/26

Table 9 EN Cements Mechanical and Physical Requirements

Class

Mechanical Requirements Compressive strength (in N/mm2) Early strength Standard strength

Physical Requirements Initial

Soundness

setting time 2 days 7 days

28 days

32.5

-

≥ 16

≥ 32.5 and ≤ 52.5

≥ 75 mins.

32.5R 42.5

≥ 10 ≥ 10

-

≥ 42.5 and ≤ 62.5

≥ 60 mins.

42.5R 52.5

≥ 20 ≥ 20

≥ 52.5

≥ 45 mins.

52.5R

≥ 30

-

≤ 10mm

ACMC Cement Standards, Testing Methods & Specifications 23/26

Table 10 EN Cement Chemical Requirements

1 Property Loss on ignition Insoluble residue Sulphate (as SO3 )

2 Test reference EN 196-2

Chemical requirements 3 4 Cement type Strength class CE I all classes

5 Requirements1) ≤ 5.0 %

EN 196-2

CE III CE I

all classes

≤ 5.0 %

EN 196-2

CE III CE I

32.5

≤ 3.5 %

CE II

2,3)

CE IV

32.5R 42.5

CE V 42.5 R 52.5 4)

52.5 R all classes all classes all classes

≤ 4.0

CE III ≤ 4.0 % Chloride EN 196-21 all types ≤ 0.10 % 5) Pozzolanicity EN 196-5 CE IV Satisfies the test 1) Requirements are given as percentages by mass. 2) This indication covers all cement types CE II/A and CE II/B including Portland composite cements containing only one other main constituent e.g. II/A - S or II/B - Q except type CE II/B - T . 3) Type CE II/B - T may contain up to 4.5 % SO3 for all strength classes . 4) Type CE III - C may contain up to 4.5 % SO3 . 5) Cement type CE III may contain more than 0.10 % chloride, but in that case the actual chloride content shall be declared .

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The EN standard permits the use of at least one, maximum four , different secondary constituents. In the most common cement type II up to 35 % secondary constituents may be applied, and it is considered to be equivalent in its performance to type I Portland cement. Generally speaking, the new EN standard very much encourages the use of secondary constituent, in particular, the industrial by - products. The performance orientation of the EN is evident from the soft limits of chemical properties. There are no limits on loss of ignition and insoluble residue for the type II cements, and the limit for all other types is as high as 5 % on these parameters. The increase of maximum permitted sulphate content in cement is also remarkable, from a common 3.0 % to 3.5 or 4.0 % respectively. There are only two main strength classes defined, with sub - classes according to early strength . Generally, these are not too many mechanical and physical requirements specified. For cements used in special applications, of course, additional requirement may be needed and the EN refers to national standard in this respect. A new feature of the EN standard is the quality assurance based on the conformity criteria. Quality control requires continuous inspection based on sampling plan providing frequent sampling. Acceptance then based on statistical principles that average value passes, with a certain probability, the lower or upper limit. The calculated error factor is also specified ( consumers’ risk 5 % ). x - kL . s ≥ L

e.g. x = average strength s = standard deviation kL = acceptance parameter L = lower strength limit

Importance of having low quality variation (low standard deviation, example of its effects see Fig. 5 ) . Concept as well as details of this part still much debated .

ACMC Cement Standards, Testing Methods & Specifications 25/26

Fig. 5: Conformity criteria – Requirements on strenght

ACMC Cement Standards, Testing Methods & Specifications 26/26

Significant progress has been made in the field of standardization of siliceous by products, such as fly - ash and slag for direct use in concrete. A review of new standards and draft standards is shown in table 11 .

Table 11 Specification for Fly - ash and Slag used in Concrete Australia AS 1129 DR 87243

( 1977 ) fly - ash for use in concrete ( 1987 ) ( draft) ground granulated iron blast furnace slag for use in concrete

Austria Canada

DR 87242 B 3320 CAN 3-A23.5

A 363 Europe EN Draft Gr. Britain BS 3892

USA

( 1987 ) ( draft ) fly - ash for use in concrete ( 1981 ) ( draft ) fly - ash for concrete ( 1986 ) supplementary cementitious materials ( 1977 ) ( 1988 ) fly - ash for concrete ( 1982 ) pulverised fuel ash for use in concrete

BS 6699

( 1986 ) ground granulated blast furnace slag for

ASTM C 618

use in concrete ( 1985 ) fly - ash for use as mineral admixture in PC concrete

ASTM C 989

( 1987 ) ground blast furnace slag for use in concrete and mortar

This development clearly shows that the direct use of siliceous by - products as binder in concrete is strongly supported by national standards, and we may expect that these products will be a quite regular constituent of concrete in the future.