Cementprinciples of

production and use

Friedrich W. Locher

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LocherCement – Principles of production and use

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Prof. Dr. rer. nat. Friedrich W. Locher

Cementprinciples of production and use

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VLB-Meldung

Locher, Friedrich Wilhelm:CementPrinciples of production and useDüsseldorf: Verlag Bau+Technik GmbH, 2006

ISBN 3-7640-0559-7

© by Verlag Bau+Technik GmbHGesamtproduktion: Verlag Bau+Technik GmbH,Postfach 12 01 10, 40601 Düsseldorfwww.verlagbt.de

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Foreword

The production and use of cement are complex processes in which important parts areplayed by the cost-ef fectiveness of the operations and the measures to protect theenvironment. An understanding of the material processes and interrelationships involvedis necessary to grasp and solve the problems that arise. This involves cement chemistry,the scope of which has widened greatly since cement was first used for building and for along time has also included the methods and discoveries of mineralogical andcrystallographic as well as chemical and physical research. This book is intended to providean overview of the current understanding of the essen tial facts of cement chemistry . Itcovers not only the composition and properties of the cements and the reactions thatoccur during their production and use but also the material problems of environmentalprotection.

The book is aimed at all chemists, physicists, engineers and technicians working in thecement industry, machine construction, the building industry, materials testing and envi-ronmental protection to provide them with the knowledge of the chemistry of cementnecessary for their work. It is also intended for use as a textbook for the study of materialsscience in colleges and universities. I have therefore tried to show the interrelationshipsin a way that is as readily understandable as possible, to explain the technical expressionsand to describe the principles of measurement on which the methods of technical andscientific investigation are based.

Since the beginning of the production of Portland cement in the middle of the 19th centurythe research in works laboratories and research establishments of the cement industry hasbeen directed towards the problems occurring during the production and use of cement.The initial focus was on the optimum composition of the raw material mix with respect toburning the cement clinker and on the soundness of the masonry mortar produced fromthe cement. After that there was the much debated problem of the use of latent hydraulicand pozzolanic substances as cement constituents, and especially their influence on thedurability of structures built with such cements. New problems arose with the increasedintroduction of energy-saving burning procedures and with the change of fuel from oil tocoal as a result of the increasing cost of crude oil. The rapid spread of ready-mixed concrete,which caused a fundamental change in the requirements for the workability properties ofthe cement, also required intensive research work, especially in relation to the optimumretardation of the setting. For a long time the cement industry has become increasinglyinvolved with environmental protection and with environmentally compatible utilizationof high-caloric wastes in the firing systems of cement kilns. Here again, the emphasis hasbeen set increasingly on chemical questions, such as the environmentally relevantconstituents of gases and aerosols.

This English edition takes account of the changes in the standards for cement and concreteand in environmental protection law that have been introduced in Europe since theappearance of the German edition in 2000.

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The book is based on the lectures that I gave at Clausthal Technical University from 1959to 1999. My special thanks for their all-round interest and encouragement go to the membersof the German Cement Works Association, its board and its management team. It was agreat help when preparing the manuscript that I had access to the extensive internationaltechnical literature in the library of the Research Institute of the Cement Industry in Düs-seldorf. I remember with thanks the willing support provided by my colleagues at theDüsseldorf Institute, at the Institute for Non-Metallic Materials of Clausthal TechnicalUniversity, at the Institute for Rock Metallurgy at Aachen College, at the College Institu-tes in Weimar and Berlin and at other college institutions.

I would also like to thank Mr Robin B.C. Baker of Cranbrook, Great Britain, for hisprofessional and dependable translation into English, as well as the staf f of VerlagBau+Technik GmbH for their cooperation and many suggestions as well as for thepublication of this book.

I dedicate my book to my dear wife, Eva Locher, who has followed its development withgreat interest and active concern, and to our sons, Dietrich, Christian and Georg, to whomI am indebted for much advice on new developments in environmental protection and forhelp in dealing with the computer.

Ratingen, August 2005 Friedrich W. Locher

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Table of contents

1 Classification of cements ……………………………………………… 171.1 Definition ……………………………………………………………… 171.2 European and German standard cements ……………………………… 17

1.2.1 General ………………………………………………………………… 171.2.2 Constituents of the European and German standard cements ………… 18

1. Portland cement clinker (K) ……………………………………… 182. Granulated blastfurnace slag (S) …………………………………… 183. Pozzolanic material (P and Q) …………………………………… 184. Fly ash (V and W) ………………………………………………… 195. Burnt shale (T) …………………………………………………… 196. Limestone (L, LL) ………………………………………………… 197. Silica fume (D) …………………………………………………… 208. Minor additional constituents ……………………………………… 209. Calcium sulfate …………………………………………………… 20

Additives …………………………………………………………… 211.2.3 Types of cement in DIN EN 197-1:2000 (Feb. 2001) ………………… 211.2.4 Application of DIN EN 197-1:2000 (Feb. 2001) in Germany ………… 211.2.5 Requirements of the cements conforming to

DIN EN 197-1:2000 (Feb. 2001) ……………………………………… 241.3Cements covered by the ASTM standards……………………………………… 26

2 History of cement ……………………………………………………… 282.1 The material basis of hydraulic binders………………………………… 282.2 Burning the cement clinker …………………………………………… 292.3 Comminution of raw materials and cement …………………………… 292.4 Environmental protection ……………………………………………… 302.5 Glassy blastfurnace slag ……………………………………………… 302.6 Cements with special properties ……………………………………… 302.7 Cement standards ……………………………………………………… 31

3 Cement clinker ………………………………………………………… 323.1 Composition of cement clinker ………………………………………… 32

3.1.1 General survey ………………………………………………………… 32

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3.1.2 Tricalcium silicate ……………………………………………………… 343.1.3 Dicalcium silicate ……………………………………………………… 353.1.4 Tricalcium aluminate …………………………………………………… 373.1.5 12/7 calcium aluminate ………………………………………………… 373.1.6 Monocalcium aluminate ……………………………………………… 393.1.7 Calcium dialuminate …………………………………………………… 393.1.8 Calcium aluminoferrite ………………………………………………… 403.1.9 Clinker compounds containing alkalis ………………………………… 41

3.1.10 Free CaO and free MgO (periclase) …………………………………… 433.1.11 Glass …………………………………………………………………… 443.1.12 Alinite ………………………………………………………………… 453.1.13 Calcium aluminosulfate 3CaO·3Al2O3·CaSO ………………………… 453.1.14 Spurrite ………………………………………………………………… 46

3.2 Production of cement clinker…………………………………………… 463.2.1 Introduction …………………………………………………………… 463.2.2 Nature of the raw materials …………………………………………… 473.2.3 Extraction and processing of the raw materials ………………………… 503.2.4 Fuels …………………………………………………………………… 533.2.5 Process technology of burning and cooling cement clinker …………… 543.2.6 Reactions during the burning and cooling of cement clinker ………… 623.2.7 Factors affecting the reactions during clinker burning ………………… 67

1. Agglomeration of the kiln feed ……………………………………… 672. Sintering behaviour of the kiln feed ………………………………… 673. Influence of additives on clinker formation and cement properties … 68

3.2.8 Energy requirement of the burning process …………………………… 691. Theoretical energy requirement for clinker formation ……………… 692. Energy requirement for evaporating the water ……………………… 713. Enthalpy content of the kiln exhaust gases ………………………… 714. Enthalpy content of the cooler exhaust air ………………………… 715. Wall losses from preheater, kiln and cooler ………………………… 716. Enthalpy content of the clinker on leaving the cooler ……………… 71

3.2.9 Factors affecting the fuel energy requirement ………………………… 733.2.10 Influence of clinker cooling on the quality of the cement

clinker and of the cement ……………………………………………… 743.2.11 Influence of the kiln atmosphere on the quality of the cement

clinker and of the cement ……………………………………………… 763.2.12 Coating formation in cement kiln systems …………………………… 79

3.3 Assessing the cement clinker…………………………………………… 813.3.1 Microscopic assessment ……………………………………………… 813.3.2 Determination of phase composition by X-ray diffraction analysis …… 833.3.3 Calculating the phase composition …………………………………… 84

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3.3.4 Lime saturation factor ………………………………………………… 863.3.5 Silica ratio ……………………………………………………………… 883.3.6 Alumina ratio …………………………………………………………… 883.3.7 Free CaO, litre weight ………………………………………………… 88

4 Other main constituents ……………………………………………… 904.1 General survey ………………………………………………………… 914.2 Granulated blastfurnace slag …………………………………………… 924.3 Burnt shale (oil shale) ………………………………………………… 964.4 Natural pozzolanas …………………………………………………… 974.5 Synthetic pozzolanas …………………………………………………… 101

4.5.1 Fly ash ………………………………………………………………… 1014.5.2 Silica fume ……………………………………………………………… 1054.5.3 Rice husk ash …………………………………………………………… 1064.5.4 Calcined clay …………………………………………………………… 106

4.6 Limestone ……………………………………………………………… 106

5 Grinding the cement ………………………………………………… 1095.1 Grinding processes …………………………………………………… 1095.2 Fineness, particle size distribution …………………………………… 1115.3 Grindability …………………………………………………………… 1155.4 Grinding aids …………………………………………………………… 118

6 Environmental protection during the manufacture of cement …… 1206.1 General review ………………………………………………………… 1206.2 Dust …………………………………………………………………… 121

6.2.1 Dust emission ………………………………………………………… 1211. Nature and quantity of the dust ……………………………………… 1212. Industrial equipment for reducing dust emission …………………… 1233. Measuring the dust emission ………………………………………… 1274. Limiting and monitoring the dust emission ………………………… 128

6.2.2 Dust dispersion, dust precipitation …………………………………… 1296.2.3 Effect of dust …………………………………………………………… 130

6.3 Vaporizable constituents, recirculating systems, balances,emission and immission ……………………………………………… 131

6.3.1 Basic principles ………………………………………………………… 1316.3.2 Recirculating dust system ……………………………………………… 1356.3.3 Alkalis ………………………………………………………………… 137

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6.3.4 Sulfur …………………………………………………………………… 1406.3.5 Fluoride ………………………………………………………………… 1426.3.6 Chloride, bromide, iodide ……………………………………………… 1436.3.7 Environmentally relevant trace elements ……………………………… 145

1. General survey ……………………………………………………… 1452. Nickel, chromium, arsenic, antimony ……………………………… 1463. Zinc, lead …………………………………………………………… 1464. Cadmium …………………………………………………………… 1495. Thallium …………………………………………………………… 1516. Mercury ……………………………………………………………… 1557. Volatility of trace elements ………………………………………… 156

6.3.8 Emission of vaporizable constituents ………………………………… 1571. Emission limitation ………………………………………………… 1572. Measuring the emissions …………………………………………… 1583. Contribution by the fuels to the emission of trace elements ………… 1604. Emission prediction, reduction of emissions ………………………… 160

6.3.9 Immission of vaporizable constituents, effect on the environment …… 1621. Immission and immission limitation ………………………………… 1622. Effect of thallium on plants ………………………………………… 162

6.4 Gases …………………………………………………………………… 1636.4.1 General review ………………………………………………………… 1636.4.2 Carbon dioxide ………………………………………………………… 1656.4.3 Carbon monoxide ……………………………………………………… 1656.4.4 Organic compounds …………………………………………………… 1666.4.5 Sulfur dioxide ………………………………………………………… 1676.4.6 Nitrogen oxides ………………………………………………………… 168

1. NO formation………………………………………………………… 1682. NO2 formation, NO-NO2 recirculation, NO ………………………… 1693. Factors affecting the NOx emission from cement kilns ……………… 1704. Selective non-catalytic NO reduction (SNCR technology) ………… 1725. Limiting the NOx emissions ………………………………………… 174

6.4.7 Removal of gaseous constituents ……………………………………… 174

7 Cement hardening …………………………………………………… 1767.1 Introduction …………………………………………………………… 1767.2 Hydration products …………………………………………………… 176

7.2.1 General survey ………………………………………………………… 1767.2.2 Calcium hydroxide, magnesium hydroxide …………………………… 1767.2.3 Calcium silicate hydrates ……………………………………………… 177

1. Solution equilibrium ………………………………………………… 177

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2. Morphology, structure ……………………………………………… 1803. Hydration of C3S and b-C2S ………………………………………… 1834. Structural elements of C–S–H ……………………………………… 1845.Calcium silicate hydrates at higher temperatures …………………… 186

7.2.4 Calcium aluminate hydrates …………………………………………… 1881. Solution equilibria, stable and metastable calcium aluminate

hydrates …………………………………………………………… 1882. C4AH19, crystal structure and de-watering characteristics ………… 189

7.2.5 Calcium ferrite hydrates ……………………………………………… 1917.2.6 Sulfatic hydrates and related compounds ……………………………… 191

1. AFt compounds ……………………………………………………… 1922. AFm compounds …………………………………………………… 1953. Syngenite …………………………………………………………… 1964. AFt and AFm compounds in hardened cement ……………………… 196

7.2.7 Hydrogarnet …………………………………………………………… 1977.2.8 Gehlenite hydrate ……………………………………………………… 198

7.3 Hydration reactions …………………………………………………… 1987.3.1 Water requirement ……………………………………………………… 1987.3.2 Bleeding ………………………………………………………………… 2047.3.3 Composition of the aqueous solution ………………………………… 2047.3.4 Course of the hydration ………………………………………………… 206

1. Portland cement ……………………………………………………… 2062. Portland oil shale cement …………………………………………… 2123. Cements containing granulated blastfurnace slag …………………… 2124. Cements containing pozzolana or fly ash …………………………… 2175. Cement with added silica fume ……………………………………… 219

7.3.5 Setting ………………………………………………………………… 2191. Setting reactions and progress ……………………………………… 2192. Factors affecting the reactivity of tricalcium aluminate Drel C3A …… 2273. Factors affecting the quantity of available sulfate …………………… 232

7.3.6 Hardening ……………………………………………………………… 2361. Cause and behaviour pattern of hardening ………………………… 2362. Influence of clinker composition …………………………………… 2383. Influence of cement composition …………………………………… 2404. Influence of fineness and particle size distribution ………………… 2435. Influence of the water/cement ratio ………………………………… 2476. Influence of additions ……………………………………………… 2477. Influence of temperature, heat-treatment, delayed ettringiteformation ……………………………………………………………… 250

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8. High-pressure steam curing ………………………………………… 2547.3.7 Heat of hydration ……………………………………………………… 255

1. General ……………………………………………………………… 2552. Heat of solution calorimeter ………………………………………… 2553. Adiabatic calorimeter………………………………………………… 2554. Semi-adiabatic process ……………………………………………… 2555. Heat flow calorimeter ……………………………………………… 2566. Heats of hydration of the cements and their constituents …………… 256

8 Constitution and properties of hardened cement paste …………… 2598.1 Water bonding ………………………………………………………… 2598.2 Specific surface area and particle size of the hydration products ……… 2668.3 Microstructure ………………………………………………………… 270

8.3.1 Models ………………………………………………………………… 2708.3.2 Void filling ……………………………………………………………… 2718.3.3 “Outer” and “inner” hydration products ……………………………… 2798.3.4 Contact zone between hardened cement paste and aggregate ………… 279

8.4 Porosity ………………………………………………………………… 2818.4.1 General survey ………………………………………………………… 2818.4.2 Methods of measurement ……………………………………………… 282

1. Pycnometer method ………………………………………………… 2822. Saturation with a liquid ……………………………………………… 2833. Capillary condensation ……………………………………………… 2844. Mercury intrusion porosimetry ……………………………………… 2855. Microscopic measuring methods …………………………………… 2856. Other methods ……………………………………………………… 286

8.4.3 Results, conclusions …………………………………………………… 2868.5 Strength ………………………………………………………………… 293

8.5.1 General ………………………………………………………………… 2938.5.2 Influence of porosity …………………………………………………… 2938.5.3 Specific strength of the hardened cement paste ……………………… 2978.5.4 Hardening, influence of the water/cement ratio and the degree

of hydration …………………………………………………………… 2978.5.5 DSP and MDF materials ……………………………………………… 300

8.6 Deformation …………………………………………………………… 3018.6.1 General survey ………………………………………………………… 3018.6.2 Modulus of elasticity …………………………………………………… 3018.6.3 Shrinkage and swelling ………………………………………………… 3028.6.4 Creep …………………………………………………………………… 303

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8.6.5 Thermal deformation …………………………………………………… 3068.7 Permeability …………………………………………………………… 309

8.7.1 General survey ………………………………………………………… 3098.7.2 Permeation ……………………………………………………………… 3098.7.3 Diffusion ……………………………………………………………… 3108.7.4 Capillary suction ……………………………………………………… 3118.7.5 Factors affecting the impermeability of hardened cement paste,

mortar and concrete …………………………………………………… 3128.7.6 Water-impermeable concrete …………………………………………… 316

8.8 Effect on metals, corrosion protection ………………………………… 3178.8.1 General review ………………………………………………………… 3178.8.2 Electrochemical reactions, standard potential ………………………… 3178.8.3 Corrosion reactions of iron …………………………………………… 3198.8.4 Carbonation of hardened cement paste, mortar and concrete ………… 3248.8.5 Action of chloride ……………………………………………………… 328

1. Corrosion mechanism ……………………………………………… 3282. Chloride combination, threshold value ……………………………… 3293. Penetration of chloride into concrete ………………………………… 3304. Factors affecting chloride-induced corrosion of steel reinforcement 332

8.8.6 Stress corrosion ………………………………………………………… 3338.8.7 Corrosion protection of the steel reinforcement ……………………… 3358.8.8 Corrosion and corrosion protection of non-ferrous metals …………… 336

8.9 Resistance to chemical attack ………………………………………… 3388.9.1 General review ………………………………………………………… 3388.9.2 Action of substances which attack concrete …………………………… 338

1. Dissolving attack …………………………………………………… 3382. Expansive attack …………………………………………………… 3403. Attack by seawater …………………………………………………… 3424. Attack by soils ……………………………………………………… 3425. Attack by gases ……………………………………………………… 342

8.9.3 Assessing the chemical attack ………………………………………… 3438.9.4 Structural preventive measures ………………………………………… 3458.9.5 Discoloration, efflorescence …………………………………………… 3468.10 Alkali-aggregate reaction ……………………………………………… 347

8.10.1 General survey ………………………………………………………… 3478.10.2 Alkali-sensitive silica and silicates in the aggregate …………………… 3488.10.3 Mechanism of the alkali-silica reaction ………………………………… 349

1. Chemical processes ………………………………………………… 3492. Effect of the alkali-silica reaction in concrete ……………………… 3503. Influence of the alkali-sensitive aggregate; “pessimum” …………… 3524. Alkali content of the cement; cement type ………………………… 354

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5. Composition of the concrete ………………………………………… 3558.10.4 Preventive measures against the concrete-damaging

alkali-silica reaction …………………………………………………… 3571. General review ……………………………………………………… 3572. Testing the alkali-sensitivity of aggregates containing silica ……… 3573. Ambient conditions ………………………………………………… 3594. Concrete technology measures ……………………………………… 361

8.10.5 Alkali-carbonate reaction ……………………………………………… 3621. Alkali-sensitive carbonate rocks …………………………………… 3622. Chemical reactions and expansion mechanism ……………………… 3623. Testing the alkali sensitivity of carbonate rocks …………………… 3634. Concrete technology measures ……………………………………… 364

8.11 Freeze-thaw resistance ………………………………………………… 3648.11.1 Mechanism of freeze-thaw attack ……………………………………… 364

1. Hydrodynamic pressure (hydraulic pressure) ……………………… 3652. Diffusion …………………………………………………………… 3653. Growth pressure of the ice crystals ………………………………… 3664. Thermal expansion of the ice crystals ……………………………… 366

8.11.2 Course of the freeze-thaw attack ……………………………………… 3678.11.3 Factors affecting the freeze-thaw attack ……………………………… 367

1. Degree of filling of the pores, degree of saturation ………………… 3672. De-icing agents ……………………………………………………… 3683. Aggregate …………………………………………………………… 3694. Air voids …………………………………………………………… 3705. Composition of the concrete ………………………………………… 3736. Carbonation ………………………………………………………… 374

8.11.4 Testing the resistance to freeze-thaw and to freeze-thawwith de-icing agent …………………………………………………… 375

9 Standard cements with special properties, special cements ……… 3799.1 General review ………………………………………………………… 3799.2 Cement with high sulfate resistance …………………………………… 380

9.2.1 Characterization ………………………………………………………… 3809.2.2 Accelerated test methods ……………………………………………… 380

1. General review ……………………………………………………… 3802. Le Chatelier-Anstett test …………………………………………… 3813. ASTM C 452 - potential expansion of Portland cement mortar during sulfate attack ………………………………………………… 3814. Sulfate expansion of low-cement mortar …………………………… 3825. Koch-Steinegger small prism method ……………………………… 382

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6. The Wittekindt flat prism method …………………………………… 3827. Comparison of the small prism and flat prism methods - investigations by the German Cement Works Association from 1957 to 1964 ………………………………………………………… 3838. Other accelerated methods ………………………………………… 385

9.2.3 Influence of cement composition and additions on sulfate resistance … 3851. Portland cement and blastfurnace cement with high sulfate resistance 3852. Concrete additions …………………………………………………… 388

9.3 Cement with low heat of hydration …………………………………… 3899.4 Cement with low effective alkali content ……………………………… 3899.5 Regulated set cement (Quick-hardening cement) ……………………… 3929.6 Expansive cement ……………………………………………………… 3929.7 Oil well cement ………………………………………………………… 3959.8 Hydrophobic cement …………………………………………………… 3989.9 Ultrafine binders ……………………………………………………… 398

9.10 Cement for sprayed concrete …………………………………………… 4009.11 Masonry cement ……………………………………………………… 4009.12 Supersulfated cement…………………………………………………… 4019.13 High-alumina cement ………………………………………………… 402

9.13.1 Definition and description ……………………………………………… 4029.13.2 Manufacture …………………………………………………………… 4039.13.3 Composition …………………………………………………………… 404

1. Chemical composition ……………………………………………… 4042. Phase composition of standard high-alumina cement ……………… 4043. Determining the phase composition of standard high-alumina cements ……………………………………………… 405

9.13.4 Hydration ……………………………………………………………… 4069.13.5 Microstructure and properties of hardened high-alumina cement ……… 4089.13.6 Transformation of the hydration products and their effect on the

properties of hardened high-alumina cement ………………………… 4099.13.7 Mixtures with other cements and cement constituents ………………… 4109.13.8 Refractory concrete made with high-alumina cement ………………… 410

10 Environmental compatibility of cement and concrete ……………… 41210.1 Cement dust …………………………………………………………… 41210.2 Alkaline action ………………………………………………………… 41210.3 Action of chromate …………………………………………………… 41210.4 Fixation of environmentally relevant substances with cement ………… 41310.5 Radioactivity and concrete …………………………………………… 414

10.5.1 Radioactive radiation …………………………………………………… 41410.5.2 Half-life value of radioactive elements ………………………………… 41510.5.3 Units of measurement for radioactivity ………………………………… 415

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10.5.4 Radioactive exposure of human beings ………………………………… 41610.5.5 Radioactivity of building materials …………………………………… 41810.5.6 Radon …………………………………………………………………… 419

11 Literature ……………………………………………………………… 423

12 Index …………………………………………………………………… 511

13 Chemical Formulae …………………………………………………… 532

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1 Classification of cements

1.1 DefinitionCement is a hydraulic binder , i.e. an inor ganic, non-metallic, finely ground substancewhich, after mixing with water , sets and hardens independently as a result of chemicalreactions with the mixing water and, after hardening, it retains its strength and stabilityeven under water. The most important area of application is therefore the production ofmortar and concrete, i.e. the bonding of natural or artificial aggregates to form a strongbuilding material which is durable in the face of normal environmental ef fects. Thedifference between mortar and concrete is governed by the particle size of the aggregate,which in mortar has a maximum value of about 4 mm and in concrete can be as large as32 mm but in special cases may be smaller or larger.Hydraulic hardening is caused primarily by the formation of calcium silicate hydrates.Cements therefore consist of those substances, or mixtures of substances which, throughreaction with the mixing water , form calcium silicate hydrates suf ficiently rapidly in aquantity sufficient to provide strength and durability . However, other compounds, e.g.calcium aluminates, may also participate in the hardening process.In contrast to these silicate cements the high-alumina cements consist predominantly ofcalcium aluminates. Their hardening is based on the formation of calcium aluminatehydrates.

1.2 European and German standard cements1.2.1 GeneralIn practically all countries there are standards for cement as a basic material for theproduction of mortar and concrete. Differences in economic and industrial development,in raw material deposits and in climatic conditions have led to the development of differ-ent construction materials and methods of construction in the dif ferent countries, andhence also to different types of cement. There are therefore also substantial differences inthe national cement standards which, among other things, also affect the specifications forthe durability of concretes produced from the cements.In Europe the work on compiling the technical basis for a European cement standard hasbeen in progress since 1975. The emphasis was initially on consistent test methods, whichare listed in EN 196 [D 42]. A Europe-wide consistent designation of the types of cement,their compositions and cement strength classes was defined in the standard EN197-1:2000[E 26]. This was based on all the cements with calcium silicate hardening which areproduced in the countries of central and western Europe for general use [A 19]. Cementswith additional special properties (special cements) and cements with different hardeningmechanisms are to be dealt with in further parts of this standard [E 26, S 193]. Of the 27cements in EN 197-1 only 12 cements were included initially in the German cement standardDIN 1164 (October 1994) [D 51]. These 12 cements were included because they hadalready proved successful with regard to the durability of concretes produced from them.

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Since 1st April 2001 the European cement standard designated DINEN 197-1:2000 (Feb.2001) has had the status of a German standard. It therefore replaces DIN 1164-1 (Oct.1994). The use of the cements specified in the new standard DIN EN 197-1 is regulatedby DIN EN 206-1 and DIN 1045-2 [D 44, D 49, w 2] (Section 1.2.4).

1.2.2 Constituents of the European and German standard cements

Cement constituents defined in DIN EN 197-1:2000 (Feb. 2001) [D 43] are:1. Portland cement clinker (K)2. Granulated blastfurnace slag (S)3. Pozzolanic material (P and Q)4. Fly ash (V and W)5. Burnt shale (T)6. Limestone (L, LL)7. Silica fume (D)8. Minor additional constituents9. Calcium sulfate

10. AdditivesThe constituents of cement are sub-divided into main and minor additional constituents[E 26, D 51]. Main constituents are the substances listed under 1 to 7, provided theircontent in the cement exceeds 5 % by mass. Minor additional constituents can be all thesubstances listed under 1 to 8, provided they have a maximum content of 5% by mass inthe cement, as well as inor ganic mineral substances from clinker production. The dataconcerning the cement composition, and also concerning the proportions of calcium sulfateand additives, always relate to the total of all main and minor additional constituents inthe cement without taking the calcium sulfate and additives into account.

1. Portland cement clinker (K)Portland cement clinker is also known as cement clinker or just clinker . At least two-thirds of it consists of the two calcium silicates, namely tri- and di-calcium silicate, whichare richest in CaO and can react with the mixing water and harden reasonably rapidly. Itis therefore a hydraulic substance.

2. Granulated blastfurnace slag (S)Granulated blastfurnace slag is a granulated, rapidly cooled, and therefore predominantlyglassy, basic blastfurnace slag. It is a latent hydraulic substance because it reacts onlyslowly with water, but when mixed with activators, such as cement clinker, it reacts andhardens relatively rapidly with the formation of calcium silicate hydrates. It must consistof at least two-thirds by mass of glassy slag and at least two-thirds of CaO, MgO and SiO2.

3. Pozzolanic material (P and Q)Pozzolanic materials are natural or industrial substances which, because of their contentof reactive silicon dioxide, SiO 2, react when finely ground in the presence of water atnormal ambient temperature with dissolved calcium hydroxide, form calcium silicatehydrates, and as a result can harden hydraulically. Reactive silicon dioxide, which is presenteither as free SiO2 or combined in aluminosilicates, is therefore essential for the pozzolanichardening. Calcium aluminate hydrates, which can also contribute to the strength formation,

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are therefore also formed. The proportion of reactive CaO is unimportant. The content ofreactive SiO2 content must be at least 25 % by mass.Although fly ash and silica fume have pozzolanic properties they are dealt with separatelyin Sections 4 and 7.Natural pozzolanas (P) are usually materials of volcanic origin or sedimentary rock ofsuitable chemical and mineralogical composition. This also includes trass as defined inDIN 51043 [D 64].Industrial pozzolanas (Q) can be thermally treated and activated clays and shales, and air-cooled slags from the extraction of lead, copper or zinc, provided they contain sufficientconcentrations of reactive SiO2.

4. Fly ash (V and W)Fly ash is obtained by electrostatic or mechanical precipitation of dust particles from theexhaust gases from furnaces. It may only be used for cement production if it comes froma furnace fired with pulverized coal. The fly ash is either an aluminosilicate or a calciumsilicate depending on how the silicon dioxide is chemically combined. Because of thecontent of reactive silicon dioxide both types have pozzolanic properties, and calciumsilicate fly ash also has hydraulic properties. In order to limit the content of incompletelyburnt substances the loss on ignition must not exceed 5.0 % by mass.Siliceous fly ash (V) is a fine powder, consisting predominantly of spherical and glassyparticles, which has pozzolanic properties. It must contain less than 5% by mass of reactiveCaO and at least 25 % by mass of reactive SiO2.Calcareous fly ash (W) is a fine powder with hydraulic and/or pozzolanic properties. Thecontent of reactive CaO must not be less than 5% by mass. Calcareous fly ash, containingbetween 5 and 15 % by mass of reactive CaO, must contain more than 25 % by mass ofreactive SiO2.

5. Burnt shale (T)Burnt oil shale has particular importance as a constituent of hydraulic binders. It is producedin a special furnace at temperatures of approximately 800 °C. Because of the content ofcalcium carbonate and sulfur in the natural starting material the burnt oil shale containsclinker phases, mainly dicalcium silicate and monocalcium aluminate, as well as smallquantities of free CaO and calcium sulfate and larger proportions of pozzolanically reactingsubstances. In a finely ground state such burnt shales therefore exhibit not only hydraulicproperties, such as those of Portland cement, but also pozzolanic properties.During strength testing in mortar in accordance with the cement standard DIN EN 196[D 42], but after moist storage instead of water storage [D 51], finely ground burnt oilshale must reach a compressive strength of 25.0 N/mm2 at 28 days. It must also be soundwhen mixed with 70 % by mass of Portland cement [D 51, D 42].

6. Limestone (L and LL)Limestone must meet the following requirements:a) The limestone must contain at least 75% by mass of CaCO3, calculated from the CaO

content

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b) The clay content, determined by the methylene blue adsorption [D46] on the pulverizedlimestone, must not exceed 1.20 g/100 g

c) The total content of carbon TOC as a measure of the content of or ganic constituents[C 8, D 47] must not exceed the following values:Limestone LL 0.20 % by massLimestone L 0.50 % by mass

7. Silica fume (D)Silica fume consists of very fine spherical particles with a content of amorphous silicondioxide SiO2 of at least 85 % by mass. Silica fume must meet the following requirements:a) The loss on ignition must not exceed 4.0 % by mass.b) The specific surface area (BET) [B 122, I 11] must be at least 15 m2/g.

8. Minor additional constituentsMinor additional constituents are natural or synthetic inorganic mineral substances which,after appropriate preparation, improve the physical properties of the cement, e.g. itsworkability or water retention, through their particle size distribution. They can be inertor have slightly hydraulic, latent hydraulic or pozzolanic properties. However , norequirements are set for them in this respect. They must be correctly prepared, i.e. selected,homogenized, dried and comminuted, to suit their state of production or delivery . Theymust not increase the water demand of the cement appreciably , impair the resistance ofthe concrete or mortar, or reduce the corrosion protection of the reinforcement.

9. Calcium sulfateCalcium sulfate, in the form of gypsum CaSO 4·2H2O or β-anhydrite (β-CaSO4), or as amixture of these compounds, is added in small quantities to the cement during itsmanufacture to control the setting. β-anhydrite is the naturally occurring modification ofwater-free CaSO4, and is also known as anhydriteII. α-anhydrite (anhydrite I) is the high-temperature modification of CaSO4, and is stable only at temperatures above 1180 °C. Ifpart of the water content of gypsum is removed hemihydrate CaSO 4·

1/2H2O is formed,while complete dehydration produces “soluble” γ-anhydrite, γ-CaSO4, also known asanhydrite III. The hemihydrate occurs in two forms, known as α- and β-hemihydrate.They both have the same crystal lattice and differ only in the way they are formed, and aretherefore not polymorphic modifications. The more coarsely crystalline α-hemihydratewith lower water demand is formed when gypsum is dehydrated in an autoclave, andβ-hemihydrate with a substantially greater specific surface area and higher water demandis formed by “dry” dewatering in rotary kilns or boilers at temperatures from 120 °C to180 °C [B 66, W 55, H 80, H 12, g 1].Gypsum and β-anhydrite occur naturally, but the calcium sulfates which are generated invarious industrial processes can also be used as setting regulators. This applies in particularto chemical gypsum, which is generated during the extraction of phosphoric acid fromcalcium phosphates (phosphogypsum) or during the extraction of hydrofluoric acid fromfluorspar (fluogypsum), as well as to FGD gypsum, i.e. gypsum from flue gasdesulfurization plants, mainly in power stations.

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10. AdditivesFor the purpose of the European and German standards cement additives are constituentswhich are used to improve the manufacture or properties of cement, e.g. grinding aids.The total quantity of these additives should not exceed 1 % by mass. If this value isexceeded the precise quantity must be stated on the packaging and/or on the deliverydocument. These additives must not promote corrosion of reinforcement or adverselyaffect the properties of the cement or of the concrete or mortar made from the cement.

1.2.3 Types of cement in DIN EN 197-1:2000 (Feb. 2001)

DIN EN 197-1:2000 [D 43] just contains cements for general use, and not cements withspecial properties. It differentiates between the following five main categories:

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

The subdivision of these five main categories into a total of 27 types of cement togetherwith their designations are shown in Table 1.1.CEM I is Portland cement containing at least 95 % by mass of Portland cement clinker.The main category CEM II covers cements which, in addition to clinker, contain one ormore main constituents in a proportion of between 6 and 35% by mass (silica fume up toa maximum of 10 % by mass). This proportion is subdivided again at 20% by mass. Thecement with the lower proportion is designated as A, and the cement with the higherproportion as B. CEM III is the designation for three types of blastfurnace cement A, Band C containing between 36 % and 95 % by mass of granulated blastfurnace slag withsubdivisions at 65 % and 80 % by mass of granulated blastfurnace slag. CEMIV denotestwo types (A and B) of pozzolanic cement containing between 1 1 and 55 % by mass ofpozzolana, with a subdivision at 35 % by mass of pozzolana. These cements must passthe pozzolana test (Section4.4). CEM V comprises composite cements which, in additionto cement clinker (K), contain 36 % to 80 % by mass of granulated blastfurnace slag (S)and/or pozzolana of natural (P) and/or industrial (Q) origin and/or siliceous fly ash (V),and are subdivided into A and B at 60 % by mass.

1.2.4 Application of DIN EN 197-1:2000 (Feb. 2001) in Germany

98 % of cement deliveries in Germany are currently (mid 2001) accounted for by just 6 ofthe 27 types of cement covered by DINEN 197-1. In addition to Portland and blastfurnacecements these are the two Portland slag cements and Portland limestone cement. Themarket share taken by these Portland composite cements has increased significantly inrecent years at the expense of Portland cement. The other cements are mainly usedregionally or for specific purposes [S 264, V 89, V 88].As binders for engineering concrete construction the types of cement previously coveredby the German cement standard DIN1164, shaded in Table 1.1, have long fulfilled all therequirements for strength development and durability. However, there has not yet sufficientpractical experience with the majority of the 15 cements newly included in the standard,

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Table 1.1: Cement types and composition of 27 cements as defi ned in DIN EN 197-1 (Febr. 2001) [D 43]. Proportion in % by mass The cements of previously applied DIN 1164 (Oct. 1994) [D 51] are characterized by shading

so their areas of application have to be restricted. This is decided by the ambient conditions, characterized by the exposure classes laid down in the standards DIN EN 206-1 and DIN 1045-2 [D 44, D 49, w 2], to which the particular component is to be assigned [V 87, V 90]. For example, there are restrictions on the use of pozzolanic cements CEM IV, composite cements CEM V, blastfurnace cements CEM III/C and some Portland composite cements CEM II-M in components which are exposed to the action of frost and/or chloride.Standard cements meet the requirements of DIN EN 197-1:2000 (Feb. 2001) or DIN 1164

a) The proportion of silica fume is limited to 10 % by mass

Cement type Main constituents

Pozzolana

Maincategory

Name Designation Portlandcementclinker

Granulatedblastfurnance

slag

Silica-fume

Natural Natural,tempered

K S Da) P Q

CEM I Portlandcement CEM I 95 …100 – – – –

CEM II Portland slag cement CEM II/A-S 80 … 94 6 … 20 – – –

CEM II/B-S 65 … 79 21 … 35 – – –

Portland silica fume cement CEM II/A-D 90 … 94 – 6 … 10 – –

Portland puzzolana cement CEM II/A-P 80 … 94 – – 6 … 20 –

CEM II/B-P 65 … 79 – – 21 … 35 –

CEM II/A-Q 80 … 94 – – – 6 … 20

CEM II/B-Q 95 … 79 – – – 21 … 35

Portland fl y ash cement CEM II/A-V 80 … 94 – – – –

CEM II/B-V 95 … 79 – – – –

CEM II/A-W 80 … 94 – – – –

CEM II/B-W 65 … 79 – – – –

Portland bumt shale cement

CEM II/A-T 80 … 94 – – – –

CEM II/B-T 65 … 79 – – – –

Portland limestone cement CEM II/A-L 80 … 94 – – – –

CEM II/B-L 65 … 79 – – – –

CEM II/A-LL 80 … 94 – – – –

CEM II/B-LL 65 … 79 – – – –

Portland composite cementb)

CEM II/A-M 80 … 94 –

CEM II/B-M 65 … 79 –

CEM III Blastfumance cement CEM III/A 35 … 64 36 … 65 – – –

CEM III/B 20 … 34 66 … 80 – – –

CEM III/C 5 … 19 81 … 95 – – –

CEM IV Puzzolanic cementb) CEM IV/A 65 … 89 – 11 … 35

CEM IV/B 45 … 64 – 36 … 55

CEM V Composite cementb) CEM V/A 40 … 64 18 … 30 – 18 … 30

CEM V/B 20 … 38 31 … 50 – 31 … 50

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(Nov. 2000). They are monitored regularly both through factory production control and by an outside testing laboratory. Conformity of the cement with the requirements of DIN EN 197-1 is indicated by the EG conformity symbol (CE symbol) which is printed on the delivery documents and the bags together with the identifying symbol of the certifying laboratory and information about the cement [F 44]. Cements with special properties as defi ned in DIN 1164 (Nov. 2000) will continued to be identifi ed by the German conformity symbol (Ü symbol).

Fortsetzung Table 1.1

Cement type Minor addi-tional

consti t-uents

Fly ash

Maincategory

Name Designation Siliceous Caleareous BurntShale

Limestone

V W T L LL

CEM I Portlandcement CEM I – – – – – 0 … 5

CEM II Portland slag cement CEM II/A-S – – – – – 0 … 5

CEM II/B-S – – – – – 0 … 5

Portland silica fume cement CEM II/A-D – – – – – 0 … 5

Portland puzzolana cement CEM II/A-P – – – – – 0 … 5

CEM II/B-P – – – – – 0 … 5

CEM II/A-Q – – – – – 0 … 5

CEM II/B-Q – – – – – 0 … 5

Portland fl y ash cement CEM II/A-V 6 … 20 – – – – 0 … 5

CEM II/B-V 21 … 35 – – – – 0 … 5

CEM II/A-W – 6 … 20 – – – 0 … 5

CEM II/B-W – 21 … 35 – – – 0 … 5

Portland bumt shale cement

CEM II/A-T – – 6 … 20 – – 0 … 5

CEM II/B-T – – 21 … 35 – – 0 … 5

Portland limestone cement CEM II/A-L – – – 6 … 20 – 0 … 5

CEM II/B-L – – – 21 … 35 – 0 … 5

CEM II/A-LL – – – – 6 … 20 0 … 5

CEM II/B-LL – – – – 21 … 35 0 … 5

Portland composite cementb)

CEM II/A-M 6 … 20 0 … 5

CEM II/B-M 21 … 35 0 … 5

CEM III Blastfumance cement CEM III/A – – – – – 0 … 5

CEM III/B – – – – – 0 … 5

CEM III/C – – – – – 0 … 5

CEM IV Puzzolanic cementb) CEM IV/A – – – 0 … 5

CEM IV/B – – – 0 … 5

CEM V Composite cementb) CEM V/A – – – – 0 … 5

CEM V/B – – – – 0 … 5b) The standard designation of Portland composite cements, pozzolanic cements and composite cements must include he characteristic letters of the main constituents other than Portland cement clinker

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1.2.5 Requirements of the cements conforming to DIN EN 197-1:2000 (Feb. 2001)

1. StrengthThe strength classes specified in the cement standard DIN EN 197-1:2000 [D 43], thecorresponding limits and the designation of the strength classes are listed in Table 1.2.There are three strength classes – 32.5, 42.5 and 52.5 – based on the standard strength at28 days. The three classes are further subdivided on the basis of their initial strength intonormal hardening (code letter N = normal) and rapid hardening cements (code letterR = rapid). The identifying colours of the cement bags and silo labels as specified inDIN 1164-1 [D 51] are given in the last two columns in Table 1.2.

Table 1.2: Strength classes of cements as defined in DIN EN 197-1:2000 (Febr. 2001) and colourcodes [D 51]

Strengthclass

Compressive strengthN/mm2

Colour-code

Colour ofimprint

Early strength Standard strength2 days

min7 days

min28 days

min max32.532.5 R42.542.5 R52.552.5 R

-1010202030

16-----

32.5

42.5

52.5

52.5

62.5

-

lightbrown

green

red

blackred

blackred

blackwhite

Table 1.3: Chemical requirements for the cements as defined in DIN EN 197-1:2000 (Febr. 2001)[D 43]

Property Testing in accordance Cement type strength class Requirement in %with by mass maximum

loss on DIN EN 196-2 CEM I all 5.0ignition CEM IIIinsoluble DIN EN 196-21) CEM I all 5.0residue CEM III

32.5 NCEM I 32.5 R 3.5

sulfate content DIN EN 196-2 CEM II 2) 42.5 N(as SO3) CEM IV 42.5 R

CEM V 52.5 N52.5 R 4.0

CEM III3) allchloride content DIN EN 196-21 all4) all 0.105)

pozzolanicity DIN EN 196-5 CEM IV all satisfies test1) Determination of the residue insoluble in hydrochloric acid and in sodium carbonate solution2) Cement type CEM II/B-T may contain up to 4.5 % by mass of SO3 in all strength classes3) Cement type CEM III/C may contain up to 4.5 % by mass of SO34) Cement type CEN III may contain more than 0.1 % by mass of chloride but in that case the actual chloride content

must be declared on the packing or in the delivery note5) For application in the manufacture of prestressed concrete cements with lower chloride content may be produced

but in that case the value of 0.1 % by mass shall be replaced by the lower value and shall be declared in thedelivery note

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Table 1.4: Requirements for cements with special properties as defined in DIN 1164 (Nov. 2000)[D 52]Cement type

CEM I to CEM V

CEM I

CEM III//BCEM III/C

CEM I to CEM V

CEM II//BB-S

CEM III/A

CEM III/B

CEM III//C

Requirements

Cement with low heat of hydration, NW-Cement

Heat of hydration after 77 days≤ 270 J/g

Cement with high sulfate resistance, HS-cement

C3A-content ≤ 3.0 % by mass 1)

Al2O3-content ≤ 5.0 % by mass

Composition according to table 1 ofDIN EN 197-1:2000 (Febr. 2001) (table 1.1)

Cement with low effective alkali content, NA-Cement

≤ 0.60 % by mass Na2O-equivalent2)

≤ 21 % by mass blastfurnance slag and≤ 0.70 % by mass Na2O-equivalent

≤ 49 % by mass blastfurnance slag and≤ 0.95 % by mass Na2O-equivalent

≤ 50 % by mass blastfurnance slag and≤ 1.10 % by mass Na2O-equivalent

Composition according to table 1 ofDIN EN 1977-1: 2000 (Febr. 2001) (table 1.1) and≤ 2.00 % by mass Na2O-equivalent

Composition according to table 1 ofDIN EN 1977-1: 2000 (Febr. 2001) (table 1.1) and≤ 2.00 % by mass Na2O-equivalent

Test methods

DIN EN 196-8

DIN EN 196-2

DIN EN 196-21

1) The content of tricalcium aluminate (3CaO·Al2O3, C3A) in % by mass is to be calculated by the followingformula: C3A = 2.65 · Al2O3 – 1.65 · Fe2O3The basis is the chemcal composition of the cement without loss on ignition, considering the CaCO3 and CaSO4compounds calculated aproximately from the contents of CO2 and SO3 of the cement. The content of CO2 is to bedetermined according DIN EN 196-21.

2) Applied to all cements

2. Physical and chemical requirementsAccording to DIN EN 197-1:2000 (Feb. 2001) [D 43] and according to the Germanstandard DIN 1164-1 [D 52] the setting as tested in accordance with DINEN 196 3 [D 42]must not start before 75 min for cements of the 32.5 strength classes, not before 60 minfor cements of the 42.5 strength classes, and not before 45 min for cements of the 52.5strength classes. There is no limit for the final setting time.The measure for soundness is the expansion during the Le Chatelier test as defined inDIN EN 196-3 [D 42]; it must not exceed 10 mm.The chemical requirements which must be fulfilled by the cements complying withDIN EN 197-1:2000 are listed in Table 1.3. The values relate to the sample in the conditionas supplied.3. Cements with special propertiesEuropean standards are not yet available for cements with special properties. The existingregulations have been retained in the new version of DIN EN 197-1 and summarized in

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DIN 1164 (Nov. 2000) [D 52]. The following cements with special properties areaccordingly standardized in Germany:– NW cements with low heat of hydration– HS cements with high sulfate resistance– NA cements with low active alkali contentThe types of cement and the requirements are shown in Table 1.4 [D 52].

1.3 Cements covered by the ASTM standardsThe ASTM standards of the United States of America are also of general importance.They contain regulations for the following cements:– Portland cement as specified in ASTM C 150 [A 46]– blended hydraulic cement of defined composition as specified in ASTM C 595M [A 60],– blended hydraulic cement with defined performance features as specified in

ASTM C 1157M [A 66],– expansive cement as specified in ASTM C 845 [A 64].According to the terminology standardized in ASTM C 219 [A 49] with respect to cement,blended hydraulic cement is a cement which is made from two or more inor ganicsubstances, of which at least one is not Portland cement or cement clinker, and is producedby intergrinding or by separate grinding and mixing. Instead of “blended hydraulic cement”the correct designation is therefore “cements made from several main constituents”. In anote in ASTM C 595M [A 60] it is pointed out that appropriate equipment and controlsare necessary to ensure the homogeneity and uniformity of these cements.The Portland cements specified in ASTM C 150 and the cements made from several mainconstituents specified in ASTM C 595 are listed in Table 1.5. With the exception of thecement types P LH and P SR, corresponding to ASTM types IV and V, all cements canalso contain air-entraining additives, indicated by A (air entrainment). The expansive cementspecified in ASTM C 845 and other cements produced in the USA are described in Section 9.

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Type ASTM Properties Type ASTM PropertiesType Type

Cements containing blastfurnace slag as defined in ASTM C 595

Slag-modified Portland cement Portland blastfurnace slag cement

PS I SM normal BLF I S normalPS MS I SM (MS) moderate sulfate resistance BLF MS I S (MS) moderate sulfate resistancePS MH I SM (MH) moderate heat of hydration BLF MH I S (MH) moderate heat of hydration

Cements containing pozzolana as defined in ASTM C 595

Pozzolan-modified Portland cement Portland pozzolan cement

PZ I PM normal POZ I P normalPZ MS I PM (MS) moderate sulfate resistance POZ MS I P (MS) moderate sulfate resistancePZ MH I PM (MH) moderate heat of hydration POZ MH I P (MH) moderate heat of hydration

Type ASTM PropertiesType

P I normalP MS II moderate sulfate resistanceP MH II moderate heat of hydrationP RH III high early strengthP LH IV low heat of hydrationP SR V high sulfate resistance

Portlandzement (P)nach ASTM C 150Portland cement

Table 1.5: Portland cements and cements consisting of several main constituents as defined inASTM C 150 and C 595With the exception of Portland cements IV and V all cements can contain air-entrainingadditives, designated by AThe designations have the following meanings

RH rapid hardeningMS moderate sulfate resistingSR high sulfate resistingMH moderate heat of hydrationLH low heat of hydration

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2 History of cement

2.1 The material basis of hydraulic bindersThe name “cement” goes back to the Romans who used the term “opus caementitium” todescribe masonry which resembled concrete and was made from crushed rock with burntlime as the binder. The volcanic ash and pulverized brick additives which were added tothe burnt lime to obtain a hydraulic binder were later referred to as cementum, cimentum,cäment and cement [Q 1, h 1, d 2, l 2].The significance of the clay content for the hydraulic properties of the hydraulic limeproduced from a natural mixture of limestone and clay was discovered by the EnglishmanJohn Smeaton (1724-1792) when he was preparing to build the Eddystone lighthousenear Plymouth and was looking for a binder for water -resistant mortar. In 1796 hiscompatriot James Parker used the name “Roman cement” for the Roman lime which heburnt from the marl nodules in London septarian clay. The Frenchman Louis-Joseph Vicat(1786-1861) and the German Johann Friedrich John (1782-1847) discovered independentlyof one another that mixtures of limestone and 25 to 30 % by mass of clay were the mostsuitable for producing hydraulic lime. The binder which Joseph Aspdin (1778-1855)produced by burning an artificial mixture of limestone and clay, and for which he obtaineda patent in 1824 under the name of “Portland cement”, also at first corresponded incomposition and properties to a Roman lime, as it had not yet been burnt to the sinteringpoint. The artificial rock produced from it resembled Portland stone, an oölitic limestonewhich is quarried on the Portland peninsula in the county of Dorset on the Channel coast.When William Aspdin, the son of Joseph Aspdin, started to produce Portland cement in1843 in a newly established works at Rotherhithe near London it became apparent,especially during the construction of the Houses of Parliament London, that this was farsuperior to “Roman cement”. This was mainly because a considerable proportion of themix had been sintered during the burning process. The significance of this sintering hadapparently been first recognized in 1844 by Isaac Charles Johnson (1811-1911) [Q 1, d 2, h 1].The first German Portland cement on the English pattern was produced in Buxtehude in1850. However, the basis for the manufacture of Portland cement in Germany was providedby Hermann Bleibtreu (1824-1881), who also built two cement works in Züllchow nearStettin (1855) and in Oberkassel near Bonn (1858).In France the manufacture of Portland cement started around 1850 when a slow-settingbinder was obtained from the sintered residues produced during the slaking of burnt limeby grinding them between mill stones.Sintered cement clinker was first manufactured in the USA around 1870 by David Saylorwho comminuted the raw material to homogenize it, and moulded the meal into bricks forburning.Wilhelm Michaëlis (1840 - 1911) had a crucial influence on the continued developmentof cement. In his book “Die hydraulischen Mörtel” (The hydraulic mortar) published in1868 he was the first to give accurate data on the most favourable composition for the raw

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