Workability and Quality Control of Concrete

273 Pages·1991·17.996 MB·\273

by  G H Tattersall (Author)

Workability and Quality
Control of Concrete
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W o r k a b i l i t y a n d Q u a l i t y
C o n t r o l o f C o n c r e t e
G.H. TATTERSALL
M.Sc, Ph.D., C.Phys., F.Inst.P., F.I. Ceram.
Honorary Reader
Department of Civil and Structural Engineering
University of Sheffield
LONDON AND NEW YORK
By Taylor & Francis,
2 Park Square, Milton Park, Abingdon, Oxon, OX14 4RN
First edition 1991
Transferred to Digital Printing 2005
© 1991 G.H. Tattersall
Typeset in 10/12pt Palatino by Excel Typesetter Company
ISBN 0 419 14860 4 0 442 31245 8 (USA)
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or review, as permitted under the UK Copyright Designs and Patents Act, 1988, this
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Enquiries concerning reproduction outside the terms stated here should be sent to the
publishers at the UK address printed on this page.
The publisher makes no representation, express or implied, with regard to the
accuracy of the information contained in this book and cannot accept any legal
responsibility or liability for any errors or omissions that may be made.
A catalogue record for this book is available from the British Library
Library of Congress Cataloging-in-Publication data
Tattersall, G.H.
Workability and quality control of concrete/G.H. Tattersall.
p. cm.
Includes bibliographical references and index.
ISBN 0-442-31245-8
1. Concrete—Testing. 2. Concrete—Quality control. I. Title
TA440.T27 1991
620.1360287—dc20 90-26033
CIP
C o n t e n t s
Preface ix
Acknowledgements x
1 The importance of workability 1
1.1 The meaning o f workability 1
1.2 Definition of workability 5
1.3 Terminology 7
1.4 Subjective assessment of workability 8
1.5 Empirical methods o f measurement 9
1.6 References 10
2 Standard tests for workability 11
2.1 Sampling 13
2.2 The slump test 14
2.3 The compacting-factor test 16
2.4 The Vebe consistometer 19
2.5 The flow-table test 2 1
2.6 Ball-penetration test 27
2.7 Precision o f the standard tests 28
2.8 General criticism o f standard tests 3 1
2.9 References 34
3 Flow properties of fresh concrete 37
4 Principles of measurement 47
5 The two-point workability test 54
5.1 Principles 54
5.2 Development 55
5.3 The apparatus 57
5.4 Modification for low-workability concretes 59
5.5 Use o f the apparatus 62
vi Contents
5.6 Experimental error 64
5.7 Oscillation of torque 66
5.8 Theoretical considerations 67
5.9 Results 70
5.10 References 73
6 Workability expressed in terms of two constants 74
6.1 Restricted validity of single-point tests 77
6.2 Significance of single-point tests 80
6.3 References 87
7 Extremely low-workability concretes 88
7.1 References 93
8 Factors affecting workability: Time and properties of mix
components 94
8.1 Introduction 94
8.2 Time 95
8.3 Properties of aggregates 99
8.4 Cement properties 111
8.5 References 119
9 Effect of mix proportions 121
9.1 Water content 121
9.2 Aggregate: cement ratio and fines content 123
9.3 Segregation and bleeding 131
9.4 Segregation during testing 135
9.5 References 137
10 Effect of chemical admixtures 139
10.1 Plasticizers and superplasticizers 139
10.2 Air entrainment 151
10.3 Combined effects 152
10.4 References 155
11 Effect of cement replacements and fibres 156
11.1 Introduction 156
11.2 Pulverised fuel ash 157
11.3 Microsilica 162
11.4 Blast furnace slag 164
11.5 Fibres 169
11.6 References 175
Contents vii
12 Workability and practical processes 176
12.1 Mixing 176
12.2 Pumping 180
12.3 Vibration 184
12.4 References 199
13 Specification of workability 202
13.1 Specification in terms o f the two-point test 205
13.2 References 212
14 Workability measurement as a means of quality control 214
14.1 Introduction 214
14.2 General principles of quality control 215
14.3 Present practice 215
14.4 Possibilities in testing for control 222
14.5 Control potential o f the two-point test 223
14.6 Quality assessment without preliminary investigations 224
14.7 Quality assessment with preliminary investigations 232
14.8 Prediction o f strength 234
14.9 Establishing a control system 237
14.10 References 242
15 Epilogue 243
Glossary 245
Appendix: BS 5328:1990 252
Conversion factors 255
Author index 257
Subject index 259

P r e f a c e
This book is a logical follow-up of the monograph The Workability of
Concrete which was published in 1976, and which was inspired by a
suggestion from the then Cement and Concrete Association, as a result
of lectures I gave for some twenty years on the Advanced Concrete
Technology Course held at the Association's Training Centre at Fulmer
Grange. Since 1976 a great deal of work has been done in studies of
workability measurement and its applications, and it has been demon
strated beyond doubt that the flow properties of fresh concrete can be
satisfactorily represented by the Bingham model. This finding has
profound implications for the industry and m y main purpose is to
discuss and elucidate those implications.
However, workability and the factors that affect it are considered
also in terms of the tests that are already familiar, although the dis
advantages of those methods are argued strongly. Like m y lectures,
and like the earlier book, this one is intended for practising engineers
and concrete technologists, and I hope it will be seen as proposing
procedures that are eminently practical, although they m a y at first
seem to be a little more complicated than those at present in use. In
fact, very little extra trouble is required and any that is should be
balanced against the benefits to be obtained in terms of a better under
standing of fresh concrete, and in increased hope of avoiding the
difficulties and disputes that are expensive in time and money.
There is very little mathematics in the book. I have not provided
proofs of any equations used but have tried to present reasonable
arguments that I hope will appeal to those w h o are engaged in getting
the job done, rather than in carrying out interesting investigations
in the absence of pressure. I have also, on occasion, simplified the
physics arguments but without sacrificing anything that is of import
ance in practical application. A n y reader w h o feels dissatisfied about
lack of rigour in any section is invited to refer to the original papers
where full arguments are given.
G.H. Tattersall