design and control of concrete mixtures1-25.pdf

8/9/2019 Design and Control of Concrete Mixtures1-25.pdf

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Design and Control

of Concrete

Mixtures

1 4 t h e d i t


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ENGINEERING BULLETIN 001

Design and Control ofConcrete Mixtures

FOURTEENTH EDITION

by Steven H. Kosmatka, Beatrix Kerkhoff, and William C. Panarese

5420 Old Orchard RoadSkokie, Illinois 60077-1083 USA

Voice: 847.966.6200Fax: 847.966.9781Internet: www.cement.org

An organization of cement companies to improve andextend the uses of portland cement and concrete throughmarket development, engineering, research, education,and public affairs work.


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Fourteenth Edition Print History

First Printing 2002, Revised 2003

© Portland Cement Association 2003

All rights reserved. No part of this book may be reproducedin any form without permission in writing from the pub-lisher, except by a reviewer who wishes to quote brief pas-sages in a review written for inclusion in a magazine ornewspaper.

Library of Congress Cataloging-in-Publication Data

Kosmatka, Steven H.Design and control of concrete mixtures / by Steven H.

Kosmatka, Beatrix Kerkhoff, and William C. Panarese.—14th ed.

p. cm.ISBN 0-89312-217-3 (pbk. : alk. paper)

1. Concrete. 2. Concrete—Additives. 3. Portland cement.I. Kerkhoff, Beatrix. II. Panarese, William C. III. Title.

TA439 .K665 2002666'.893—dc21

2001007603

PCA R&D Serial Number SN2561

Printed in the United States of America

EB001.14

WARNING: Contact with wet (unhardened) concrete,mortar, cement, or cement mixtures can cause SKINIRRITATION, SEVERE CHEMICAL BURNS (THIRD-DEGREE), or SERIOUS EYE DAMAGE. Frequent expo-sure may be associated with irritant and/or allergic con-tact dermatitis. Wear waterproof gloves, a long-sleevedshirt, full-length trousers, and proper eye protection when

working with these materials. If you have to stand in wetconcrete, use waterproof boots that are high enough tokeep concrete from flowing into them. Wash wet con-crete, mortar, cement, or cement mixtures from your skinimmediately. Flush eyes with clean water immediatelyafter contact. Indirect contact through clothing can be asserious as direct contact, so promptly rinse out wet con-crete, mortar, cement, or cement mixtures from clothing.Seek immediate medical attention if you have persistentor severe discomfort.

This publication is intended SOLELY for use by PROFES-SIONAL PERSONNEL who are competent to evaluate thesignificance and limitations of the information providedherein, and who will accept total responsibility for the

application of this information. The Portland CementAssociation DISCLAIMS any and all RESPONSIBILITY andLIABILITY for the accuracy of and the application of theinformation contained in this publication to the full extentpermitted by law.

The authors of this engineering bulletin are:

Steven H. Kosmatka, Managing Director, Research and Technical Services, PCA

Beatrix Kerkhoff, Civil Engineer, Product Standards and Technology, PCA

William C. Panarese, former Manager, Construction Information Services, PCA

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KEYWORDS: admixtures, aggregates, air-entrained concrete, batching, cement, cold weather, curing, durability, fibers,finishing, high-performance concrete, hot weather, mixing, mixing water, mixture proportioning, placing, portland cementconcrete, properties, special concrete, standards, supplementary cementing materials, tests, and volume changes.

ABSTRACT: This book presents the properties of concrete as needed in concrete construction, including strength anddurability. All concrete ingredients (cementing materials, water, aggregates, admixtures, and fibers) are reviewed for theiroptimal use in designing and proportioning concrete mixtures. Applicable ASTM, AASHTO, and ACI standards arereferred to extensively. The use of concrete from design to batching, mixing, transporting, placing, consolidating, finishing,and curing is addressed. Special concretes, including high-performance concretes, are also reviewed.

REFERENCE: Kosmatka, Steven H.; Kerkhoff, Beatrix; and Panarese, William C.; Design and Control of Concrete Mixtures,EB001, 14th edition, Portland Cement Association, Skokie, Illinois, USA, 2003.

Cover photos show ready mixed concrete being elevated by bucket andcrane to the 39th floor of a high-rise building in Chicago. (69991, 70015)


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Preface and Acknowledgements . . . . . . . . . . . . . . . . . . . . ix

Chapter 1

Fundamentals of Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . 1Freshly Mixed Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Mixing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Workability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Bleeding and Settlement . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Consolidation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Hydration, Setting Time, and Hardening . . . . . . . . . . . . . 4

Hardened Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Curing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Drying Rate of Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Permeability and Watertightness . . . . . . . . . . . . . . . . . . . . 9

Abrasion Resistance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Volume Stability and Crack Control. . . . . . . . . . . . . . . . . 11 Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Durability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Resistance to Freezing and Thawing . . . . . . . . . . . . . . . . 12Alkali-Aggregate Reactivity . . . . . . . . . . . . . . . . . . . . . . . 13Carbonation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Chloride Resistance and Steel Corrosion. . . . . . . . . . . . . 14Chemical Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Sulfate Attack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Seawater Exposures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Ettringite and Heat Induced

Delayed Expansion . . . . . . . . . . . . . . . . . . . . . . . . . . 17Heat Induced Delayed Expansion . . . . . . . . . . . . . . . . 17

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Chapter 2Portland, Blended, and Other Hydraulic Cements . . . 21

The Beginning of an Industry. . . . . . . . . . . . . . . . . . . . . . . . 21Manufacture of Portland Cement. . . . . . . . . . . . . . . . . . . . . 24Types of Portland Cement. . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Type I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Type II. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Type III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Type IV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Type V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Air-Entraining Portland Cements. . . . . . . . . . . . . . . . . . . 30White Portland Cements. . . . . . . . . . . . . . . . . . . . . . . . . . 30

Blended Hydraulic Cements. . . . . . . . . . . . . . . . . . . . . . . . . 31Type IS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Type IP and Type P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Type I (PM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Type S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Type I (SM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Hydraulic Cements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Type GU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Type HE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Type MS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Type HS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Type MH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Type LH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Hydraulic Slag Cements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Modified Portland Cements . . . . . . . . . . . . . . . . . . . . . . . . . 33

Special Cements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Masonry and Mortar Cements . . . . . . . . . . . . . . . . . . . . . 33

Plastic Cements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Finely-Ground Cements (Ultrafine Cements) . . . . . . . . . 35

Expansive Cements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Oil-Well Cements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Cements with Functional Additions . . . . . . . . . . . . . . . . 36

Water-Repellent Cements . . . . . . . . . . . . . . . . . . . . . . . . . 36

Regulated-Set Cements . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Geopolymer Cements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Ettringite Cements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Rapid Hardening Cements . . . . . . . . . . . . . . . . . . . . . . . . 37Calcium Aluminate Cements . . . . . . . . . . . . . . . . . . . . . . 37

Magnesium Phosphate Cements . . . . . . . . . . . . . . . . . . . 37

Sulfur Cements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Selecting and Specifying Cements . . . . . . . . . . . . . . . . . . . . 37

Availability of Cements . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Drinking Water Applications . . . . . . . . . . . . . . . . . . . . . . 38

Canadian and European CementSpecifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Chemical Compounds and Hydrationof Portland Cement . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Tricalcium Silicate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Dicalcium Silicate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Tricalcium Aluminate . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Tetracalcium Aluminoferrite. . . . . . . . . . . . . . . . . . . . . 42Calcium Sulfate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Water (Evaporable and Nonevaporable) . . . . . . . . . . . . . 42

Physical Properties of Cement . . . . . . . . . . . . . . . . . . . . . . . 43

Particle Size and Fineness . . . . . . . . . . . . . . . . . . . . . . . . . 43

Soundness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Consistency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Setting Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Early Stiffening (False Set and Flash Set). . . . . . . . . . . . . 46

Compressive Strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Heat of Hydration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Loss on Ignition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Density and Relative Density(Specific Gravity) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Bulk Density. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Thermal Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Thermogravimetric Analysis (TGA). . . . . . . . . . . . . . . . . 51

Differential Thermal Analysis (DTA) . . . . . . . . . . . . . . . . 51

Differential Scanning Calorimetry (DSC) . . . . . . . . . . . . 51

Virtual Cement Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Transportation and Packaging . . . . . . . . . . . . . . . . . . . . . . . 52

Storage of Cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Hot Cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

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Table of Contents


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Chapter 3Fly Ash, Slag, Silica Fume, andNatural Pozzolans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Fly Ash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Slag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Silica Fume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Natural Pozzolans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Effects on Freshly Mixed Concrete. . . . . . . . . . . . . . . . . . . . 61

Water Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Workability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Bleeding and Segregation . . . . . . . . . . . . . . . . . . . . . . . . . 62

Air Content. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Heat of Hydration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Setting Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Finishability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Pumpability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Plastic Shrinkage Cracking . . . . . . . . . . . . . . . . . . . . . . . . 64

Curing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Effects on Hardened Concrete . . . . . . . . . . . . . . . . . . . . . . . 64

Strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Impact and Abrasion Resistance. . . . . . . . . . . . . . . . . . . . 65

Freeze-Thaw Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . 65Deicer-Scaling Resistance . . . . . . . . . . . . . . . . . . . . . . . . . 66

Drying Shrinkage and Creep . . . . . . . . . . . . . . . . . . . . . . 67

Permeability and Absorption . . . . . . . . . . . . . . . . . . . . . . 68

Alkali-Aggregate Reactivity . . . . . . . . . . . . . . . . . . . . . . . 68

Sulfate Resistance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Corrosion of Embedded Steel . . . . . . . . . . . . . . . . . . . . . . 69

Carbonation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Chemical Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Soundness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Concrete Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Concrete Mix Proportions . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Chapter 4Mixing Water for Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Alkali Carbonate and Bicarbonate . . . . . . . . . . . . . . . . . . . . 74

Chloride . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Sulfate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Other Common Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Iron Salts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Miscellaneous Inorganic Salts. . . . . . . . . . . . . . . . . . . . . . . . 75

Seawater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Acid Waters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Alkaline Waters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76Wash Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Industrial Wastewater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Waters Carrying Sanitary Sewage . . . . . . . . . . . . . . . . . . . . 77

Organic Impurities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Sugar. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Silt or Suspended Particles . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Oils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Algae. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Interaction with Admixtures. . . . . . . . . . . . . . . . . . . . . . . . . 77

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Chapter 5Aggregates for Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Characteristics of Aggregates . . . . . . . . . . . . . . . . . . . . . . . . 80Grading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80Fine-Aggregate Grading . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Fineness Modulus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84Coarse-Aggregate Grading . . . . . . . . . . . . . . . . . . . . . . . . 84Combined Aggregate Grading . . . . . . . . . . . . . . . . . . . . . 86

Gap-Graded Aggregates . . . . . . . . . . . . . . . . . . . . . . . . . . 86Particle Shape and Surface Texture . . . . . . . . . . . . . . . . . 87Bulk Density (Unit Weight) and Voids. . . . . . . . . . . . . . . 87Relative Density (Specific Gravity) . . . . . . . . . . . . . . . . . 87Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88Absorption and Surface Moisture . . . . . . . . . . . . . . . . . . 88

Bulking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88Resistance to Freezing and Thawing . . . . . . . . . . . . . . . . 89Wetting and Drying Properties. . . . . . . . . . . . . . . . . . . . . 90Abrasion and Skid Resistance. . . . . . . . . . . . . . . . . . . . . . 90Strength and Shrinkage. . . . . . . . . . . . . . . . . . . . . . . . . . . 91Resistance to Acid and Other

Corrosive Substances. . . . . . . . . . . . . . . . . . . . . . . . . 91Fire Resistance and Thermal Properties. . . . . . . . . . . . . . 92

Potentially Harmful Materials . . . . . . . . . . . . . . . . . . . . . . . 92Alkali-Aggregate Reactivity . . . . . . . . . . . . . . . . . . . . . . . . . 93

Alkali-Silica Reaction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93Visual Symptoms of Expansive ASR . . . . . . . . . . . . . . 93Mechanism of ASR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94Factors Affecting ASR . . . . . . . . . . . . . . . . . . . . . . . . . . 94Test Methods for Identifying ASR Distress . . . . . . . . . 94Control of ASR in New Concrete . . . . . . . . . . . . . . . . . 94Identification of Potentially

Reactive Aggregates. . . . . . . . . . . . . . . . . . . . . . . . . . 95Materials and Methods to Control ASR. . . . . . . . . . . . 95

Alkali-Carbonate Reaction . . . . . . . . . . . . . . . . . . . . . . . . 95Mechanism of ACR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Dedolomitization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98Test Methods for Identifying ACR Distress . . . . . . . . . 98Materials and Methods to Control ACR . . . . . . . . . . . 98

Aggregate Beneficiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98Handling and Storing Aggregates . . . . . . . . . . . . . . . . . . . . 98Marine-Dredged Aggregate . . . . . . . . . . . . . . . . . . . . . . . . . 99Recycled-Concrete Aggregate. . . . . . . . . . . . . . . . . . . . . . . . 99References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Chapter 6Admixtures for Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . 105

Air-Entraining Admixtures. . . . . . . . . . . . . . . . . . . . . . . . . 107Water-Reducing Admixtures. . . . . . . . . . . . . . . . . . . . . . . . 107Mid-Range Water Reducing Admixtures. . . . . . . . . . . . . . 109

High-Range Water Reducing Admixtures . . . . . . . . . . . . . 109Plasticizers for Flowing Concrete . . . . . . . . . . . . . . . . . . . . 110Retarding Admixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113Hydration-Control Admixtures . . . . . . . . . . . . . . . . . . . . . 113Accelerating Admixtures. . . . . . . . . . . . . . . . . . . . . . . . . . . 113Corrosion Inhibitors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114Shrinkage-Reducing Admixtures . . . . . . . . . . . . . . . . . . . . 115Chemical Admixtures to Reduce Alkali-

Aggregate Reactivity (ASR Inhibitors) . . . . . . . . . . 115Coloring Admixtures (Pigments) . . . . . . . . . . . . . . . . . . . . 115Dampproofing Admixtures. . . . . . . . . . . . . . . . . . . . . . . . . 116Permeability-Reducing Admixtures . . . . . . . . . . . . . . . . . . 116

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Pumping Aids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116Bonding Admixtures and Bonding Agents . . . . . . . . . . . . 116Grouting Admixtures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117Gas-Forming Admixtures . . . . . . . . . . . . . . . . . . . . . . . . . . 117Air Detrainers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117Fungicidal, Germicidal, and

Insecticidal Admixtures. . . . . . . . . . . . . . . . . . . . . . 117Antiwashout Admixtures . . . . . . . . . . . . . . . . . . . . . . . . . . 117

Compatibility of Admixtures andCementitious Materials . . . . . . . . . . . . . . . . . . . . . . 117Storing and Dispensing Chemical

Admixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

Chapter 7Fibers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

Advantages and Disadvantagesof Using Fibers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

Types and Properties of Fibers andTheir Effect on Concrete . . . . . . . . . . . . . . . . . . . . . 122

Steel Fibers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122Glass Fibers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124Synthetic Fibers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

Natural Fibers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126Unprocessed Natural Fibers . . . . . . . . . . . . . . . . . . . . 126Wood Fibers (Processed Natural Fibers) . . . . . . . . . . 126

Multiple Fiber Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

Chapter 8Air-Entrained Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

Properties of Air-Entrained Concrete. . . . . . . . . . . . . . . . . 129Freeze-Thaw Resistance . . . . . . . . . . . . . . . . . . . . . . . . . 129Deicer-Scaling Resistance . . . . . . . . . . . . . . . . . . . . . . . . 132

Air Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134Treatment of Scaled Surfaces . . . . . . . . . . . . . . . . . . . 134

Sulfate Resistance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134Resistance to Alkali-Silica Reactivity . . . . . . . . . . . . . . . 134Strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134Workability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

Air-Entraining Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . 136Factors Affecting Air Content . . . . . . . . . . . . . . . . . . . . . . . 137

Cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137Coarse Aggregate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138Fine Aggregate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138Mixing Water and Slump . . . . . . . . . . . . . . . . . . . . . . . . 138Slump and Vibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141Concrete Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . 142Supplementary Cementitious Materials . . . . . . . . . . . . 142Admixtures and Coloring Agents . . . . . . . . . . . . . . . . . 142

Mixing Action. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143Transporting and Handling . . . . . . . . . . . . . . . . . . . . . . 144Finishing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

Tests for Air Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144Air-Void Analysis of Fresh Concrete . . . . . . . . . . . . . . . 145

Recommended Air Contents. . . . . . . . . . . . . . . . . . . . . . . . 145References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

Chapter 9Designing and ProportioningNormal Concrete Mixtures . . . . . . . . . . . . . . . . . . . . . . . . . 149

Selecting Mix Characteristics . . . . . . . . . . . . . . . . . . . . . . . 149

Water-Cementing Materials Ratioand Strength Relationship. . . . . . . . . . . . . . . . . . . . 149

Strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150Water-Cementitious Material Ratio . . . . . . . . . . . . . . . . 151Aggregates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151Air Content. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

Mild Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153Moderate Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

Severe Exposure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153Slump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153Water Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155Cementing Materials Content and Type . . . . . . . . . . . . 156Admixtures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

Proportioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157Proportioning from Field Data . . . . . . . . . . . . . . . . . . . . 157Proportioning by Trial Mixtures . . . . . . . . . . . . . . . . . . . 158Measurements and Calculations. . . . . . . . . . . . . . . . . . . 159

Density (Unit Weight) and Yield. . . . . . . . . . . . . . . . . 159Absolute Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

Examples of Mixture Proportioning. . . . . . . . . . . . . . . . . . 160Example 1. Absolute Volume Method

(Metric) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160Conditions and Specifications. . . . . . . . . . . . . . . . . . . 160Strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160Water to Cement Ratio. . . . . . . . . . . . . . . . . . . . . . . . . 160Air Content. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160Slump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160Water Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160Cement Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160Coarse-Aggregate Content . . . . . . . . . . . . . . . . . . . . . 161Admixture Content . . . . . . . . . . . . . . . . . . . . . . . . . . . 161Fine-Aggregate Content . . . . . . . . . . . . . . . . . . . . . . . 161Moisture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161Trial Batch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161Batch Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

Example 2. Absolute Volume Method(Inch-Pound Units) . . . . . . . . . . . . . . . . . . . . . . . . . 163

Conditions and Specifications. . . . . . . . . . . . . . . . . . . 163Strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163Water to Cement Ratio. . . . . . . . . . . . . . . . . . . . . . . . . 163Coarse-Aggregate Size. . . . . . . . . . . . . . . . . . . . . . . . . 163Air Content. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163Slump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163Water Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163Cement Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163Coarse-Aggregate Content . . . . . . . . . . . . . . . . . . . . . 163Admixture Content . . . . . . . . . . . . . . . . . . . . . . . . . . . 163Fine-Aggregate Content . . . . . . . . . . . . . . . . . . . . . . . 163

Moisture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164Trial Batch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164Batch Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165Water Reducers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166Pozzolans and Slag . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

Example 3. Laboratory Trial MixtureUsing the PCA Water-CementRatio Method (Metric) . . . . . . . . . . . . . . . . . . . . . . . 166

Conditions and Specifications. . . . . . . . . . . . . . . . . . . 166Durability Requirements. . . . . . . . . . . . . . . . . . . . . . . 166Strength Requirements . . . . . . . . . . . . . . . . . . . . . . . . 166Aggregate Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

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Internal Moist Curing . . . . . . . . . . . . . . . . . . . . . . . . . . . 224Forms Left in Place . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224Steam Curing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224Insulating Blankets or Covers. . . . . . . . . . . . . . . . . . . . . 225Electrical, Oil, Microwave, and

Infrared Curing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225

Curing Period and Temperature. . . . . . . . . . . . . . . . . . . . . 225Sealing Compounds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228

Chapter 13Hot-Weather Concreting . . . . . . . . . . . . . . . . . . . . . . . . . . . 229

When to Take Precautions. . . . . . . . . . . . . . . . . . . . . . . . . . 229Effects of High Concrete Temperatures . . . . . . . . . . . . . . . 230Cooling Concrete Materials. . . . . . . . . . . . . . . . . . . . . . . . . 231

Supplementary Cementitious Materials . . . . . . . . . . . . . . 234Preparation Before Concreting . . . . . . . . . . . . . . . . . . . . . . 234Transporting, Placing, Finishing. . . . . . . . . . . . . . . . . . . . . 235Plastic Shrinkage Cracking . . . . . . . . . . . . . . . . . . . . . . . . . 235Curing and Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237Admixtures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

Heat of Hydration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

Chapter 14Cold-Weather Concreting. . . . . . . . . . . . . . . . . . . . . . . . . . 239

Effect of Freezing Fresh Concrete. . . . . . . . . . . . . . . . . . . . 239Strength Gain of Concrete at

Low Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . 240Heat of Hydration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241

Special Concrete Mixtures. . . . . . . . . . . . . . . . . . . . . . . . . . 242Air-Entrained Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242Temperature of Concrete. . . . . . . . . . . . . . . . . . . . . . . . . . . 243

Temperature of Concrete as Mixed. . . . . . . . . . . . . . . . . 243Aggregate Temperature. . . . . . . . . . . . . . . . . . . . . . . . 244Mixing-Water Temperature . . . . . . . . . . . . . . . . . . . . . 244

Temperature of Concrete asPlaced and Maintained . . . . . . . . . . . . . . . . . . . . . . 245

Cooling After Protection . . . . . . . . . . . . . . . . . . . . . . . . . 245Control Tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245Concreting on Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246Concreting Aboveground . . . . . . . . . . . . . . . . . . . . . . . . . . 247Enclosures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249

Insulating Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250Heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251Duration of Heating. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253

Moist Curing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253Terminating the Heating Period . . . . . . . . . . . . . . . . . . . 253

Form Removal and Reshoring . . . . . . . . . . . . . . . . . . . . . . 253

Maturity Concept. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255

Chapter 15Volume Changes of Concrete. . . . . . . . . . . . . . . . . . . . . . 257

Early Age Volume Changes . . . . . . . . . . . . . . . . . . . . . . . . 257Chemical Shrinkage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257

Autogenous Shrinkage . . . . . . . . . . . . . . . . . . . . . . . . . . 258Subsidence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259Plastic Shrinkage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259Swelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259Early Thermal Expansion . . . . . . . . . . . . . . . . . . . . . . . . 260

Moisture Changes (Drying Shrinkage)of Hardened Concrete . . . . . . . . . . . . . . . . . . . . . . . 260

Effect of Concrete Ingredients onDrying Shrinkage. . . . . . . . . . . . . . . . . . . . . . . . . . . 263

Effect of Curing on Drying Shrinkage . . . . . . . . . . . . . . 264Temperature Changes of

Hardened Concrete . . . . . . . . . . . . . . . . . . . . . . . . . 264Low Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265High Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265

Curling (Warping) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266Elastic and Inelastic Deformation. . . . . . . . . . . . . . . . . . . . 267

Compression Strain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267Modulus of Elasticity. . . . . . . . . . . . . . . . . . . . . . . . . . . . 267Deflection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268Poisson’s Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268Shear Strain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268Torsional Strain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268

Creep. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268Chemical Changes and Effects . . . . . . . . . . . . . . . . . . . . . . 270

Carbonation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270Sulfate Attack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270Alkali-Aggregate Reactions. . . . . . . . . . . . . . . . . . . . . . . 270

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271

Chapter 16Control Tests for Concrete . . . . . . . . . . . . . . . . . . . . . . . . 275

Classes of Tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275Frequency of Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275Testing Aggregates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276

Sampling Aggregates. . . . . . . . . . . . . . . . . . . . . . . . . . . . 276Organic Impurities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276Objectionable Fine Material . . . . . . . . . . . . . . . . . . . . . . 277Grading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277Moisture Content of Aggregates. . . . . . . . . . . . . . . . . . . 277

Testing Freshly Mixed Concrete . . . . . . . . . . . . . . . . . . . . . 279Sampling Freshly Mixed Concrete . . . . . . . . . . . . . . . . . 279Consistency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279Temperature Measurement . . . . . . . . . . . . . . . . . . . . . . . 280Density and Yield. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280Air Content. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280Strength Specimens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282Time of Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283Accelerated Compression Tests to

Project Later-Age Strength . . . . . . . . . . . . . . . . . . . 284Chloride Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284Portland Cement Content, Water Content,

and Water Cement Ratio . . . . . . . . . . . . . . . . . . . . . 284Supplementary Cementitious

Materials Content. . . . . . . . . . . . . . . . . . . . . . . . . . . 284

Bleeding of Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284Testing Hardened Concrete. . . . . . . . . . . . . . . . . . . . . . . . . 285

Strength Tests of Hardened Concrete. . . . . . . . . . . . . . . 285Evaluation of Compression Test Results . . . . . . . . . . 287

Air Content. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287Density, Relative Density (Specific

Gravity), Absorption, and Voids. . . . . . . . . . . . . . . 288Portland Cement Content . . . . . . . . . . . . . . . . . . . . . . . . 289Supplementary Cementitious Material and

Organic Admixture Content . . . . . . . . . . . . . . . . . . 289Chloride Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289Petrographic Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 289

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10/25

Concrete’s versatility, durability, and economy have madeit the world’s most used construction material. The UnitedStates uses about 260 million cubic meters (340 millioncubic yards) of ready mixed concrete each year. It is usedin highways, streets, parking lots, parking garages,

bridges, high-rise buildings, dams, homes, floors, side-walks, driveways, and numerous other applications.

Design and Control of Concrete Mixtures has been thecement and concrete industry’s primary reference on con-crete technology for over 75 years. Since the first edition

was published in the early 1920s, the U.S. version has beenupdated 14 times to reflect advances in concrete technolo-gy and to meet the growing needs of architects, engineers,

builders, concrete producers, concrete technologists,instructors, and students.

This fully revised 14th edition was written to providea concise, current reference on concrete, including themany advances that occurred since the last edition waspublished in 1988. The text is backed by over 85 years of research by the Portland Cement Association. It reflects thelatest information on standards, specifications, and testmethods of the American Society for Testing and Materials(ASTM), the American Association of State Highway andTransportation Officials (AASHTO), and the AmericanConcrete Institute (ACI).

Besides presenting a 50% increase in new informationover the previous edition, this edition has added metricunits that are currently required on most federal govern-ment projects and many state projects; AASHTO stan-dards commonly used by many state departments of transportation are provided alongside ASTM standards;internet addresses are provided for many references forinstant access; new photographs have been added to illus-trate modern technology; and included are appendices onmetric unit conversion, ASTM and AASHTO standards,

and a listing of key concrete organizations and their webaddresses. New chapters on supplementary cementingmaterials, fibers, and high-performance concrete have also

been added.

Acknowledgements. The authors wish to acknowledgecontributions made by many individuals and organiza-tions who provided valuable assistance in the writingand publishing of the 14th edition. A special thanks toKen Hover, Cornell University, for extensive technicalrecommendations; Howard “Buck” Barker, RVT En-gineering Services, for photography and text edits; and

Cheryl Taylor, Consultant, for months of desktop layout.Additional thanks for technical assistance, references, pho-tography, and editorial reviews goes to: Norm MacLeod,former Cement Association of Canada; Rick McGrath,Cement Association of Canada; John Bickley, John A.Bickley Associates, Ltd.; Hamid Farzam, ConstructionTechnology Laboratories (CTL); Colin Lobo, NationalReady Mixed Concrete Association; Linda Hills, CTL(SEM); Connie Field, PCA; Bill Burns, PCA; John Shaw,PCA; Basile Rabbat, PCA; Arlene Zapata, PCA (cover

design); Wes Ikezoe, PCA; Richard Small, PCA; BruceMcIntosh, PCA; Susan Pepitone, PCA; Dale McFarlane,PCA; Paul Tennis, PCA; John Melander, PCA; Jamie Farny,PCA; Carmaline Spurrier, PCA; Martin McGovern, PCA;Terry Collins, PCA; Michelle Wilson, PCA; Tony Fiorato,CTL; Vagn Johansen, CTL; Wally Klemm, formerly of CTL;Peter Marlo, CTL; Ron Bard, CTL; Manoj Bharucha, CTL;

Javed Bhatty, CTL; Jennifer DeStrampe, Ground Heaters,Inc.; Jim Shilstone, Shilstone Companies, Inc.; Robert E.Neal, Lehigh Portland Cement Co.; Gregory S. Barger, AshGrove Cement Co.; Mark Luther, Holcim (US) Inc.; Fred Cohrs,Florida Rock Industries, Inc.; Phil Zacarias, LafargeCanada, Inc.; Terry Holland, Silica Fume Association;

Oscar Manz, Consultant; Jon Mullarky, FHWA; KarenGruber, Hercules, Inc.; Mike Pistilli, Prairie Group; SamTyson, American Coal Ash Association; Craig Plunk,Mineral Solutions; Jim Jensen, Mineral Solutions; JohnRivisto, AVR, Inc.; Charlie Misslin, County Concrete Corp.;

Jamison Langdon, Cemstone; Kerry Smith, James Cape &Sons Co.; David Meyer, Lafarge North America, Inc.; LewKollmansberger, Mead & Hunt, Inc.; Tim Roble, MidwayConcrete Corp.; George Barker, River Valley Testing Corp.;Dan Large, SI Concrete Systems; EJ Streu, StreuConstruction; Len Swederski, Swederski Concrete Const.,Inc.; Pat Bauer, W. R. Grace Co.; Darrin G. Stanke, ZenithTech, Inc.; Scott Zignego, Zignego Ready Mix, Inc.; Peter

Waisamen, Trow Engineers; Mette Geiker, Technical Uni-versity of Denmark; and numerous others who have pro-vided comments and suggestions on EB001 over the pastseveral years. Thanks also goes to ASTM, AASHTO, andACI for the use of their material and documents referencedthroughout the book.

The authors have tried to make this edition of Designand Control of Concrete Mixtures a concise and current ref-erence on concrete technology. Readers are encouraged tosubmit comments to improve future printings and edi-tions of this book.

ix

Preface and Acknowledgements


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Concrete is basically a mixture of two components: aggre-gates and paste. The paste, comprised of portland cementand water, binds the aggregates (usually sand and gravelor crushed stone) into a rocklike mass as the paste hardens

because of the chemical reaction of the cement and water(Fig. 1-1). Supplementary cementitious materials andchemical admixtures may also be included in the paste.*

Aggregates are generally divided into two groups: fineand coarse. Fine aggregates consist of natural or manufac-tured sand with particle sizes ranging up to 9.5 mm ( 3 ⁄ 8 in.);coarse aggregates are particles retained on the 1.18 mm(No. 16) sieve and ranging up to 150 mm (6 in.) in size. Themaximum size of coarse aggregate is typically 19 mm or25 mm (3 ⁄ 4 in. or 1 in.). An intermediate-sized aggregate,around 9.5 mm (3 ⁄ 8 in.), is sometimes added to improve theoverall aggregate gradation.

CHAPTER 1

Fundamentals of Concrete

The paste is composed of cementitious materials,water, and entrapped air or purposely entrained air. Thepaste constitutes about 25% to 40% of the total volume of concrete. Fig. 1-2 shows that the absolute volume of cementis usually between 7% and 15% and the water between 14%and 21%. Air content in air-entrained concrete ranges fromabout 4% to 8% of the volume.

Since aggregates make up about 60% to 75% of thetotal volume of concrete, their selection is important.Aggregates should consist of particles with adequatestrength and resistance to exposure conditions and should

not contain materials that will cause deterioration of theconcrete. A continuous gradation of aggregate particlesizes is desirable for efficient use of the paste. Throughoutthis text, it will be assumed that suitable aggregates are

being used, except where otherwise noted.The quality of the concrete depends upon the quality

of the paste and aggregate, and the bond between the two.In properly made concrete, each and every particle of aggregate is completely coated with paste and all of thespaces between aggregate particles are completely filledwith paste, as illustrated in Fig. 1-3.

* This text addresses the utilization of portland cement in the production of concrete. The term “portland cement” pertains to a calcium silicate hydrauliccement produced by heating materials containing calcium, silicon,aluminum, and iron. The term “cement” used throughout the text pertains toportland cement or blended hydraulic cement unless otherwise stated. Theterm “cementitious materials” means portland or blended cement, used withor without supplementary cementitious materials.

Fig. 1-1. Concrete components: cement, water, fine aggre-gate and coarse aggregate, are combined to form concrete.(55361)

Air-

entrained

concrete

Non-air-

entrained

concrete

Cement15%

Water18%

Fine agg.28%

Coarse agg.31%

Air8%

7% 14% 4% 24% 51%

15% 21% 3% 30% 31%

7% 16% 1% 25% 51%

Mix 1

Mix 2

Mix 3

Mix 4

Fig. 1-2. Range in proportions of materials used in concrete,by absolute volume. Bars 1 and 3 represent rich mixes withsmall size aggregates. Bars 2 and 4 represent lean mixeswith large size aggregates.

1


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13/25

Mixing

In Fig. 1-1, the basic components of concrete are shownseparately. To ensure that they are combined into a homo-geneous mixture requires effort and care. The sequence of charging ingredients into a concrete mixer can play an im-portant part in uniformity of the finished product. Thesequence, however, can be varied and still produce a qual-

ity concrete. Different sequences require adjustments in thetime of water addition, the total number of revolutions of the mixer drum, and the speed of revolution. Other impor-tant factors in mixing are the size of the batch in relation tothe size of the mixer drum, the elapsed time between batch-ing and mixing, and the design, configuration, and condi-tion of the mixer drum and blades. Approved mixers,correctly operated and maintained, ensure an end-to-endexchange of materials by a rolling, folding, and kneadingaction of the batch over itself as concrete is mixed.

Workability

The ease of placing, consolidating, and finishing freshlymixed concrete and the degree to which it resists segrega-tion is called workability. Concrete should be workable butthe ingredients should not separate during transport andhandling (Fig. 1-5).

The degree of workability required for properplacement of concrete iscontrolled by the place-ment method, type of con-solidation, and type of concrete. Different types of placements require differ-ent levels of workability.

Factors that influencethe workability of concreteare: (1) the method andduration of transportation;(2) quantity and character-istics of cementitious ma-terials; (3) concrete consis-tency (slump); (4) grading,shape, and surface textureof fine and coarse aggre-gates; (5) entrained air; (6)water content; (7) concrete

and ambient air temperatures; and (8) admixtures. A uni-form distribution of aggregate particles and the presence of entrained air significantly help control segregation andimprove workability. Fig. 1-6 illustrates the effect of castingtemperature on the consistency, or slump, and potentialworkability of concrete mixtures.

Properties related to workability include consistency,segregation, mobility, pumpability, bleeding, and finishabil-ity. Consistency is considered a close indication of workabil-ity. Slump is used as a measure of the consistency or wetnessof concrete. A low-slump concrete has a stiff consistency. If

the consistency is too dry and harsh, the concrete will bedifficult to place and compact and larger aggregate particlesmay separate from the mix. However, it should not beassumed that a wetter, more fluid mix is necessarily moreworkable. If the mix is too wet, segregation and honey-combing can occur. The consistency should be the driestpracticable for placement using the available consolidationequipment. See Powers (1932) and Scanlon (1994).

Bleeding and Settlement

Bleeding is the development of a layer of water at the top or

surface of freshly placed concrete. It is caused by sedimen-tation (settlement) of solid particles (cement and aggregate)and the simultaneous upward migration of water (Fig. 1-7).Bleeding is normal and it should not diminish the quality of properly placed, finished, and cured concrete. Some bleed-ing is helpful to control plastic shrinkage cracking.

3

Chapter 1 ◆ Fundamentals of Concrete

Casting temperature, °F

Casting temperature, °C

32 52 72 92200

150

100

50

0 0

S l u m p ,

m m

S l u m p , i n .

8

6

4

2

Cement A

Cement B

0 10 20 30 40

Fig. 1-5. Workable concreteshould flow sluggishly intoplace without segregation.(59292)

Fig. 1-6. Effect of casting temperature on the slump (andrelative workability) of two concretes made with differentcements (Burg 1996).

Fig. 1-7. Bleed water on the surface of a freshly placedconcrete slab. (P29992)


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with paste and the less aggregate surface area there is tocoat with paste; thus less water and cement are needed.Concrete with an optimally graded aggregate will be easier

to consolidate and place (Fig. 1-8 left). Consolidation of coarser as well as stiffer mixtures results in improved qual-ity and economy. On the other hand, poor consolidation canresult in porous, weak concrete (Fig. 1-9) with poor durabil-ity (Fig. 1-8 right).

Mechanical vibra-tion has many advan-tages. Vibrators make itpossible to economi-cally place mixturesthat are impractical toconsolidate by handunder many conditions.

As an example, Fig.1-10 shows concrete of astiff consistency (lowslump). This concretewas mechanically vi-

brated in forms contain-ing closely spaced rein-forcement. With handrodding, a much wetterconsistency would have

been necessary.

Hydration, Setting Time, and Hardening

The binding quality of portland cement paste is due to thechemical reaction between the cement and water, calledhydration.

Portland cement is not a simple chemical compound, itis a mixture of many compounds. Four of these make up90% or more of the weight of portland cement: tricalciumsilicate, dicalcium silicate, tricalcium aluminate, and tetra-calcium aluminoferrite. In addition to these major com-pounds, several others play important roles in the hydrationprocess. Each type of portland cement contains the samefour major compounds, but in different proportions.

Excessive bleeding increases thewater-cement ratio near the top surface;a weak top layer with poor durabilitymay result, particularly if finishing oper-ations take place while bleed water ispresent. A water pocket or void candevelop under a prematurely finishedsurface.

After evaporation of all bleed water,the hardened surface will be slightlylower than the freshly placed surface.This decrease in height from time of placement to initial set is called settle-ment shrinkage.

The bleeding rate and bleedingcapacity (total settlement per unit of original concrete height) increases withinitial water content, concrete height,and pressure. Use of properly graded aggregate, certainchemical admixtures, air entrainment, supplementary ce-mentitious materials, and finer cements, reduces bleeding.

Concrete used to fill voids, provide support, or providewatertightness with a good bond should have low bleed-ing properties to avoid formation of water pockets. SeePowers (1939) , Steinour (1945) , and Kosmatka (1994).

Consolidation

Vibration sets into motion the particles in freshly mixedconcrete, reducing friction between them, and giving themixture the mobile qualities of a thick fluid. The vibratoryaction permits use of a stiffer mixture containing a largerproportion of coarse and a smaller proportion of fine aggre-gate. The larger the maximum size aggregate in concretewith a well-graded aggregate, the less volume there is to fill

4

Design and Control of Concrete Mixtures ◆ EB001

100

80

60

40

20

0

0 5 10 15 20 25 30

Voids, %

Compressive strength

Flexural strength

Modulus of elasticity

R e d u c t i o n i n c

o n c r e t e p r o p e r t i e s ,

%

Fig. 1-9. Effect of voids in concrete due to a lack of consoli-dation on modulus of elasticity, compressive strength, andflexural strength.

Fig. 1-8. Good consolidation (left) is needed to achieve a dense and durableconcrete. Poor consolidation (right) can result in early corrosion of reinforcingsteel and low compressive strength. (70016, 68806)

Fig. 1-10. Concrete of a stiffconsistency (low slump). (44485)


15/25

When clinker (the kiln product that is ground to makeportland cement) is examined under a microscope, most of the individual cement compounds can be identified andtheir amounts determined. However, the smallest grainselude visual detection. The average diameter of a typicalcement particle is approximately 15 micrometers. If allcement particles were average, portland cement wouldcontain about 300 billion particles per kilogram, but in factthere are some 16,000 billion particles per kilogram becauseof the broad range of particle sizes. The particles in a kilo-gram of portland cement have a surface area of approxi-mately 400 square meters.

The two calcium silicates, which constitute about 75%of the weight of portland cement, react with water to formtwo new compounds: calcium hydroxide and calcium sili-cate hydrate. The latter is by far the most important cement-ing component in concrete. The engineering properties of concrete—setting and hardening, strength, and dimen-sional stability—depend primarily on calcium silicatehydrate. It is the heart of concrete.

The chemical composition of calcium silicate hydrate issomewhat variable, but it contains lime (CaO) and silicate(SiO2) in a ratio on the order of 3 to 2. The surface area of calcium silicate hydrate is some 300 square meters pergram. In hardened cement paste, the calcium silicatehydrate forms dense, bonded aggregations between theother crystalline phases and the remaining unhydratedcement grains; they also adhere to grains of sand and topieces of coarse aggregate, cementing everything together(Copeland and Schulz 1962).

As concrete hardens, its gross volume remains almostunchanged, but hardened concrete contains pores filledwith water and air that have no strength. The strength is inthe solid part of the paste, mostly in the calcium silicatehydrate and crystalline compounds.

The less porous the cement paste, the stronger theconcrete. When mixing concrete, therefore, no more waterthan is absolutely necessary to make the concrete plasticand workable should be used. Even then, the water used isusually more than is required for complete hydration of thecement. About 0.4 grams of water per gram of cement areneeded to completely hydrate cement (Powers 1948 and1949). However, complete hydration is rare in fieldconcrete due to a lack of moisture and the long period of time (decades) required to achieve complete hydration.

Knowledge of the amount of heat released as cementhydrates can be useful in planning construction. In winter,the heat of hydration will help protect the concrete againstdamage from freezing temperatures. The heat may be harm-ful, however, in massive structures such as dams because itmay produce undesirable temperature differentials.

Knowledge of the rate of reaction between cement andwater is important because it determines the rate of hard-ening. The initial reaction must be slow enough to allowtime for the concrete to be transported and placed. Oncethe concrete has been placed and finished, however, rapid

hardening is desirable. Gypsum, added at the cement millwhen clinker is ground, acts as a regulator of the initial rateof setting of portland cement. Other factors that influencethe rate of hydration include cement fineness, admixtures,amount of water added, and temperature of the materialsat the time of mixing. Fig. 1-11 illustrates the setting prop-erties of a concrete mixture at different temperatures.

HARDENED CONCRETE

Curing

Increase in strength with age continues provided (1) un-hydrated cement is still present, (2) the concrete remainsmoist or has a relative humidity above approximately 80%(Powers 1948) , (3) the concrete temperature remains favor-able, and (4) sufficient space is available for hydration prod-ucts to form. When the relative humidity within the concretedrops to about 80%, or the temperature of the concrete drops

below freezing, hydration and strength gain virtually stop.Fig. 1-12 illustrates the relationship between strength gainand moist curing, while Fig. 1-13 illustrates the relationship

between strength gain and curing temperature.If concrete is resaturated after a drying period, hydra-

tion is resumed and strength will again increase. However,it is best to moist-cure concrete continuously from the timeit is placed until it has attained the desired quality; onceconcrete has dried out it is difficult to resaturate. Fig. 1-14illustrates the long-term strength gain of concrete in anoutdoor exposure. Outdoor exposures often continue toprovide moisture through ground contact and rainfall.Indoor concretes often dry out after curing and do notcontinue to gain strength (Fig. 1-12).

5


0

1

2

3

4

5

6

7

0

10

20

30

40

0 2 4 6 8 10 12 14

P e n e t r a t i o n r e s i s t a

n c e ,

1 0 0 0 p s i

P e n e t r a t i o n r e s i s t a n c e ,

M P a

Time, hr

Cured at 32°C (90°F)

23°C (73°F)

10°C (50°F)

Initial Set

Final Set

ASTM C 403(AASHTO T 22)

Fig. 1-11. Initial and final set times for a concrete mixture atdifferent temperatures (Burg 1996).


16/25

For example, as mentioned, concrete must continue to holdenough moisture throughout the curing period for thecement to hydrate to the extent that desired properties areachieved. Freshly cast concrete usually has an abundanceof water, but as drying progresses from the surface inward,strength gain will continue at each depth only as long asthe relative humidity at that point remains above 80%.

A common illustration of this is the surface of aconcrete floor that has not had sufficient moist curing.Because it has dried quickly, concrete at the surface is weak

and traffic on it creates dusting. Also, when concrete dries,it shrinks as it loses water (Fig. 1-15), just as wood and claydo (though not as much). Drying shrinkage is a primarycause of cracking, and the width of cracks is a function of the degree of drying, spacing or frequency of cracks, andthe age at which the cracks occur.

While the surface of a concrete element will dry quiterapidly, it takes a much longer time for concrete in the inte-rior to dry. Fig. 1-15 (top) illustrates the rate of drying atvarious depths within concrete cylinders exposed to labo-ratory air. Field concrete elements would have differentdrying profiles due to environmental conditions, size

effects, and concrete properties.The moisture content of concrete depends on theconcrete’s constituents, original water content, dryingconditions, and the size of the concrete element (Heden-

blad 1997 and 1998). After several months of drying in airwith a relative humidity of 50% to 90%, moisture content isabout 1% to 2% by mass of the concrete. Fig. 1-15 illustratesmoisture loss and resulting shrinkage.

Size and shape of a concrete member have an impor-tant bearing on the rate of drying. Concrete elements withlarge surface area in relation to volume (such as floor slabs)

Drying Rate of Concrete

Concrete does not harden or cure by drying. Concrete (or more

precisely, the cement in it) needs moisture to hydrate and

harden. When concrete dries out, it ceases to gain strength; the

fact that it is dry is no indication that it has undergone sufficient

hydration to achieve the desired physical properties.

Knowledge of the rate of drying is helpful in under-

standing the properties or physical condition of concrete.

6


60

50

40

30

20

10

00 7 28 91 365

8

6

4

2

0

Age at test, days

Moist-cured entire time

In air after 28 days moist curing

In air after 7 days moist curing

In laboratory air entire time

C o m p r e s s i v e

s t r e n g t h ,

M P a

C o m p r e s s i v e s t r e n g t h ,

1 0 0 0 p s i

Fig. 1-12. Concrete strength increases with age as long asmoisture and a favorable temperature are present forhydration of cement (Gonnerman and Shuman 1928).

Outdoor exposure - Skokie, Illinois150-mm (6-in.) modified cubesType I cement

0

20

40

60

80

100

C o m p r e s

s i v e s t r e n g t h , p s i


M P a

w/c = 0.40

w/c = 0.53

w/c = 0.71

3d 7d 28d 3m 1y 3y 5y 10y 20yAge at Test

14000

12000

10000

8000

6000

4000

2000

0

Fig. 1-14. Concrete strength gain versus time for concreteexposed to outdoor conditions. Concrete continues to gainstrength for many years when moisture is provided byrainfall and other environmental sources (Wood 1992).

0

10

20

30

40

50

0 10 20 30

C o m p

r e s s i v e s t r e n g t h ,

M P a

C o m p

r e s s i v e s t r e n g t h , p s i

Age, days

10/10 (50/50)

23/10 (73/50)

23/23 (73/73)

32/32 (90/90)

Casting/curing temperature, °C °(F)

7000

6000

5000

4000

3000

2000

1000

0

Fig. 1-13. Effect of casting and curing temperature onstrength development. Note that cooler temperatures resultin lower early strength and higher later strength (Burg,1996).


17/25

dry faster than voluminous concrete members with rela-tively small surface areas (such as bridge piers).

Many other properties of hardened concrete also areaffected by its moisture content; these include elasticity,creep, insulating value, fire resistance, abrasion resistance,electrical conductivity, frost resistance, scaling resistance,and resistance to alkali-aggregate reactivity.

Strength

Compressive strength may be defined as the measuredmaximum resistance of a concrete specimen to axial load-

ing. It is generally expressed in megapascals (MPa) orpounds per square inch (psi) at an age of 28 days. Onemegapascal equals the force of one newton per squaremillimeter (N/mm2) or 1,000,000 N/m2. Other test ages arealso used; however, it is important to realize the relation-ship between the 28-day strength and other test ages.Seven-day strengths are often estimated to be about 75% of

the 28-day strength and 56-day and 90-day strengths areabout 10% to 15% greater than 28-day strengths as shownin Fig. 1-16. The specified compressive strength is desig-nated by the symbol ̆, and ideally is exceeded by theactual compressive strength, ¯.

The compressive strength that a concrete achieves, ̄,results from the water-cement ratio (or water-cementitiousmaterials ratio), the extent to which hydration hasprogressed, the curing and environmental conditions, andthe age of the concrete. The relationship between strengthand water-cement ratio has been studied since the late1800s and early 1900s (Feret 1897 and Abrams 1918). Fig.1-17 shows compressive strengths for a wide range of concrete mixtures and water-cement ratios at an age of 28days. Note that strengths increase as the water-cementratios decrease. These factors also affect flexural and tensilestrengths and bond of concrete to steel.

The water-cement ratio compressive strength relation-ships in Fig. 1-17 are for typical non-air-entrained con-cretes. When more precise values for concrete are required,graphs should be developed for the specific materials andmix proportions to be used on the job.

For a given workability and a given amount of cement,air-entrained concrete requires less mixing water than non-air-entrained concrete. The lower water-cement ratio possi-

ble for air-entrained concrete tends to offset the somewhatlower strengths of air-entrained concrete, particularly inlean to medium cement content mixes.

7


50

60

70

80

90

100

R e l a t i v e h u m i d i t y , p e r c e n t

0

200

400

600

800

S h r i n k a g e , m i l l i o n t h s

0

0.1

0.2

0.3

0.4

0.5

0.6

0 75 150 225 300 375

M a s s l o s s ,

k g

Time of drying, days

Normal-density concrete

Normal-density concrete

Cement content: 270 kg/m3 (454 lb/cu yd)

Normal-density concretew/c ratio: 0.66

75 mm (3 in.) depth

45 (13 / 4)

6 (1 / 4)

20 (3 / 4)

Fig. 1-15. Relative humidity distribution, drying shrinkage,and mass loss of 150 x 300-mm (6 x 12-in.) cylinders moistcured for 7 days followed by drying in laboratory air at 23°C(73°F) (Hanson 1968).

0

20

40

60

80

100

120

140

160

180

1 10 100 1000 10000

P e r c e n t o f 2

8 - d a y s t r e n g t h

Age, days

28 days

Concrete cylinders

Fig. 1-16. Compressive strength development of variousconcretes illustrated as a percentage of the 28-day strength(Lange 1994).


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The torsional strength for concrete is related to themodulus of rupture and the dimensions of the concreteelement. Hsu (1968) presents torsional strength correlations.

Shear strength–compressive strength relationships arediscussed in the ACI 318 building code. The correlation

between compressive strength and flexural, tensile,torsional, and shear strength varies with concrete ingredi-ents and environment.

Modulus of elasticity, denoted by the symbol E , may be defined as the ratio of normal stress to correspondingstrain for tensile or compressive stresses below the propor-tional limit of a material. For normal-weight concrete, Eranges from 14,000 to 41,000 MPa (2 to 6 million psi) and

can be approximated as 5,000 times the square root of thecompressive strength in megapascals (57,000 times thesquare root of the compressive strength in pounds persquare inch). Like other strength relationships, the modu-lus of elasticity to compressive strength relationship is mix-ingredient specific and should be verified in a laboratory(Wood 1992).

Density

Conventional concrete, normally used in pavements, build-ings, and other structures, has a density (unit weight) in the

range of 2200 to 2400 kg/m3 (137 to 150 lb/ft 3). The densityof concrete varies, depending on the amount and density of the aggregate, the amount of air that is entrapped or pur-posely entrained, and the water and cement contents,which in turn are influenced by the maximum size of theaggregate. Reducing the cement paste content (increasingaggregate volume) increases density. Values of the densityof fresh concrete are given in Table 1-1. In the design of re-inforced concrete structures, the combination of conven-tional concrete and reinforcing steel is commonly assumedto weigh 2400 kg/m3 (150 lb/ft 3).

To determine compressive strength, tests are made onspecimens of mortar or concrete; in the United States,unless otherwise specified, compression tests of mortar aremade on 50-mm (2-in.) cubes, while compression tests of concrete are made on cylinders 150 mm (6 in.) in diameterand 300 mm (12 in.) high (see Fig. 1-18). Smaller cylinders,100 x 200 mm (4 x 8 in.) are also used for concrete.

Compressive strength of concrete is a primary physicalproperty and frequently used in design calculations for

bridges, buildings, and other structures. Most general-useconcrete has a compressive strength between 20 and 40MPa (3000 and 6000 psi). Compressive strengths of 70 to140 MPa (10,000 to 20,000 psi) have been used in special

bridge and high-rise building applications.The flexural strength or modulus of rupture of

concrete is used to design pavements and other slabs onground. Compressive strength, which is easier to measurethan flexural strength, can be used as an index of flexuralstrength, once the empirical relationship between them has

been established for the materials and the size of theelement involved. The flexural strength of normal-weightconcrete is often approximated as 0.7 to 0.8 times the squareroot of the compressive strength in megapascals (7.5 to 10times the square root of the compressive strength inpounds per square inch). Wood (1992) illustrates the rela-

tionship between flexural strength and compressivestrength for concretes exposed to moist curing, air curing,and outdoor exposure.

The direct tensile strength of concrete is about 8% to12% of the compressive strength and is often estimated as0.4 to 0.7 times the square root of the compressive strengthin megapascals (5 to 7.5 times the square root of thecompressive strength in pounds per square inch). Splittingtensile strength is 8% to 14% of the compressive strength(Hanson 1968). Splitting tensile strength versus time ispresented by Lange (1994).

8


28-day strength

Moist cured cylinders

0

10

20

30

40

50

60

70

80

0.25 0.35 0.45 0.55 0.65 0.75 0.85


M P a


p s i

Water-cement ratio

10000

8000

6000

4000

2000

0

Fig. 1-17. Range of typical strength to water-cement ratiorelationships of portland cement concrete based on over100 different concrete mixtures cast between 1985 and 1999.

Fig. 1-18. Testing a 150 x 300-mm (6 x 12-in.) concretecylinder in compression. The load on the test cylinder isregistered on the display. (68959)


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The weight of dry concrete equals the weight of thefreshly mixed concrete ingredients less the weight of mixwater that evaporates into the air. Some of the mix watercombines chemically with the cement during the hydrationprocess, converting the cement into cement gel. Also, someof the water remains tightly held in pores and capillaries

and does not evaporate under normal conditions. Theamount of mix water that will evaporate from concreteexposed to ambient air at 50% relative humidity is about1 ⁄ 2% to 3% of the concrete weight; the actual amountdepends on initial water content of the concrete, absorptioncharacteristics of the aggregates, and size and shape of theconcrete element.

Aside from conventional concrete, there is a wide spec-trum of special concretes to meet various needs; they rangefrom lightweight insulating concretes with a density of aslittle as 240 kg/m3 (15 lb/ft3) to heavyweight concrete witha density of up to 6000 kg/m3 (375 lb/ft3) used for coun-

terweights or radiation shielding.

Permeability and Watertightness

Concrete used in water-retaining structures or exposed toweather or other severe exposure conditions must be virtu-ally impermeable or watertight. Watertightness is oftenreferred to as the ability of concrete to hold back or retainwater without visible leakage. Permeability refers to theamount of water migration through concrete when thewater is under pressure or to the ability of concrete to resist

penetration by water or other substances (liquid, gas, orions). Generally, the same properties of concrete that makeit less permeable also make it more watertight.

The overall permeability of concrete to water is a func-tion of: (1) the permeability of the paste; (2) the permeabil-ity and gradation of the aggregate; (3) the quality of the

paste and aggregate transition zone; and (4) the relativeproportion of paste to aggregate. Decreased permeabilityimproves concrete’s resistance to freezing and thawing,resaturation, sulfate, and chloride-ion penetration, andother chemical attack.

The permeability of the paste is particularly important because the paste envelops all constituents in the concrete.Paste permeability is related to water-cement ratio, degreeof cement hydration, and length of moist curing. A low-permeability concrete requires a low water-cement ratioand an adequate moist-curing period. Air entrainment aidswatertightness but has little effect on permeability.Permeability increases with drying.

The permeability of mature hardened cement pastekept continuously moist ranges from 0.1 x 10-12 to 120 x 10-12

cm per sec. for water-cement ratios ranging from 0.3 to 0.7(Powers and others 1954).The permeability of rock commonly used as concrete aggregate varies from approx-imately 1.7 x 10-9 to 3.5 x 10-13 cm per sec. The permeabilityof mature, good-quality concrete is approximately 1 x 10-10

cm per sec.The relationship between permeability, water-cement

ratio, and initial curing for 100 x 200-mm (4 x 8-in.) cylin-drical concrete specimens tested after 90 days of air drying

9


Maximum Density, kg/m3**

size of Air Relative density of aggregate†aggregate, content, Water, Cement,

mm percent kg/m3 kg/m3 2.55 2.60 2.65 2.70 2.75

19 6.0 168 336 2194 2227 2259 2291 232337.5 4.5 145 291 2259 2291 2339 2371 2403

75 3.5 121 242 2307 2355 2387 2435 2467

Table 1-1. Observed Average Density of Fresh Concrete (SI Units)*

* Source: Bureau of Reclamation 1981 , Table 4.** Air-entrained concrete with indicated air content.† On saturated surface-dry basis. Multiply relative density by 1000 to obtain density of aggregate particles in kg/m3.

Maximum Density, lb/ft3**

size of Air Specific gravity of aggregate†aggregate, content, Water, Cement,

in. percent lb/yd3 lb/yd3 2.55 2.60 2.65 2.70 2.75

3 ⁄ 4 6.0 283 566 137 139 141 143 14511 ⁄ 2 4.5 245 490 141 143 146 148 1503 3.5 204 408 144 147 149 152 154

Table 1-1. Observed Average Density of Fresh Concrete (Inch-Pound Units)*

* Source: Bureau of Reclamation 1981 , Table 4.** Air-entrained concrete with indicated air content.† On saturated surface-dry basis. Multiply specific gravity by 62.4 to obtain density of aggregate particles in lb/ft3.


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greatly reduced or completely removed, producing a highvolume of air voids. Pervious concrete has been used in

tennis courts, pavements, parking lots, greenhouses, anddrainage structures. Pervious concrete has also been usedin buildings because of its thermal insulation properties.

Abrasion Resistance

Floors, pavements, and hydraulic structures are subjectedto abrasion; therefore, in these applications concrete musthave a high abrasion resistance. Test results indicate thatabrasion resistance is closely related to the compressivestrength of concrete. Strong concrete has more resistance to

and subjected to 20 MPa (3000 psi) of water pressure isillustrated in Fig. 1-19. Although permeability valueswould be different for other liquids and gases, the relation-ship between water-cement ratio, curing period, andpermeability would be similar.

Test results obtained by subjecting 25-mm (1-in.) thick non-air-entrained mortar disks to 140-kPa (20-psi) waterpressure are given in Fig. 1-20. In these tests, there was no

water leakage through mortar disks that had a water-cement ratio of 0.50 by weight or less and were moist-curedfor seven days. Where leakage occurred, it was greater inmortar disks made with high water-cement ratios. Also, foreach water-cement ratio, leakage was less as the length of the moist-curing period increased. In disks with a water-cement ratio of 0.80, the mortar still permitted leakage after

being moist-cured for one month. These results clearlyshow that a low water-cement ratio and a reasonableperiod of moist curing significantly reduce permeability.

Fig. 1-21 illustrates the effect of different water to ce-ment ratios on concrete’s resistance to chloride ion penetra-

tion as indicated by electrical conductance. The total chargein coulombs was significantly reduced with a low water tocement ratio. Also, the results showed that a lower chargepassed when the concrete contained a higher air content.

A low water-cement ratio also reduces segregation and bleeding, further contributing to watertightness. Of coursewatertight concrete must also be free from cracks, honey-comb, or other large visible voids.

Occasionally, pervious concrete—no-fines concretethat readily allows passage of water—is designed forspecial applications. In these concretes, the fine aggregate is

10


0

10

20

30

40

50

0.3 0.4 0.5 0.6 0.7 0.8

H y d r a u l i c p e r m e a b i l i t y , c m / s e c x 1 0 - 1 0

Water-cement ratio, by mass

1 day moist, 90 daysin air

7 days moist, 90days in air

Non-air-entrained concrete

Specimens: 100 x 200-mm (4 x 8-in.) cylinders

Water pressure: 20 MPa (3000 psi)

Curing:

Fig. 1-19. Relationship between hydraulic (water) perme-ability, water-cement ratio, and initial curing on concretespecimens (Whiting 1989).

0.0

2.5

5.0

7.5

10.0

12.5

0.0

0.5

1.0

1.5

2.0

2.5

0 7 14 21 28

L e a k a g e ,

k g / ( m 2

• h ) , a v e r a g e f o r 4 8 h o u r s

L e a k a g e , p s f p e r h o u r

Period of moist curing and age at test, days

w/c ratio: 0.80

Non-air-entrained concreteSpecimens: 25 x 150-mm (1 x 6-in.)

mortar disks

Pressure: 140 kPa (20 psi)

w/c ratio: 0.64

w/c ratio: 0.50

Fig. 1-20. Effect of water-cement ratio (w/c) and curingduration on permeability of mortar. Note that leakage isreduced as the water-cement ratio is decreased and thecuring period increased (McMillan and Lyse 1929 and PCAMajor Series 227).

3000

4000

2000

1000

0

Water to cement ratio

C u m u l a t i v e c h a r g e , c o u l o m b s

0.2 0.3 0.4 0.5

2%

4%6%

Air content

ASTM C 1202

Fig. 1-21. Total charge at the end of the rapid chloridepermeability test as a function of water to cement ratio(Pinto and Hover 2001).


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abrasion than does weak concrete. Since compressivestrength depends on water-cement ratio and curing, a lowwater-cement ratio and adequate curing are necessary forabrasion resistance. The type of aggregate and surfacefinish or treatment used also have a strong influence onabrasion resistance. Hard aggregate is more wear resistantthan soft aggregate and a steel-troweled surface resistsabrasion better than a surface that had not been troweled.

Fig. 1-22 shows results of abrasion tests on concretes of different compressive strengths and aggregate types. Fig.1-23 illustrates the effect hard steel troweling and surface

treatments, such as metallic or mineral aggregate surfacehardeners, have on abrasion resistance. Abrasion tests can

be conducted by rotating steel balls, dressing wheels, ordisks under pressure over the surface (ASTM C 779). Onetype of test apparatus is pictured in Fig. 1-24. Other typesof abrasion tests are also available (ASTM C 418 and C 944).

Volume Stability and Crack Control

Hardened concrete changes volume due to changes intemperature, moisture, and stress. These volume or lengthchanges may range from about 0.01% to 0.08%. Thermalvolume changes of hardened concrete are about the sameas those for steel.

Concrete under stress will deform elastically. Sus-tained stress will result in additional deformation calledcreep. The rate of creep (deformation per unit of time)decreases with time.

Concrete kept continually moist will expand slightly.When permitted to dry, concrete will shrink. The primaryfactor influencing the amount of drying shrinkage is thewater content of the freshly mixed concrete. Drying shrink-age increases directly with increases in this water content.The amount of shrinkage also depends upon several other

11


0

2

4

6

8

10

20 30 40 50 60 70

3 4 5 6 7 8 9 10

A b r a s i o n - e r o s i o n l o s s , p e r c e n t b y m a s s

Compressive strength, MPa

Compressive strength, 1000 psi

Aggregate type

Limestone

Quartzite

Traprock

Chert

Fig. 1-22. Effect of compressive strength and aggregate typeon the abrasion resistance of concrete (ASTM C 1138). High-strength concrete made with a hard aggregate is highlyresistant to abrasion (Liu 1981).

0

20

40

60

80

100

120

0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.500

T i m e , m i n u t e s

Depth of abrasion, mm

Dressing-wheel abrasion test

Traprocktopping

Traprock surfacetreatment

Metallic aggregatesurface treatment

Monolithic single-course slab

Fig. 1-23. Effect of hard steel troweling and surface treat-ments on the abrasion resistance of concrete (ASTM C 779).Base slab compressive strength was 40 MPa (6000 psi) at 28days. All slabs were steel troweled (Brinkerhoff 1970).

Fig. 1-24. Test apparatus for measuring abrasion resistanceof concrete. The machine can be adjusted to use eitherrevolving disks or dressing wheels. With a differentmachine, steel balls under pressure are rolled over thesurface of the specimen. The tests are described in ASTM C779. (44015)


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