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PREFACE:

hird edition builds upon the shoulders of the work done for the first two, and I do not wish those I thanked then to be forgotten now. Therefore the acknowledgements in the second edition are reprinted in full following those for the current edition. 

My company, Concrete Advice Pty Ltd, was sold in 2001 to Maricopa Readymix, my first U.S. client, at the instigation of Dave Hudder, at that time managing director of Maricopa. I have him to thank for his  recognition of the value of ConAd in the United States and for providing me with the means to enjoy my semiretirement and to travel the world preaching my concepts.

 Upon Dave leaving Maricopa, Concrete Advice was on-sold to Command Alkon. I was very pleased about this because ConAd is a perfect fit for a major, worldwide batching-system provider. I thank them for continuing my part-time consultancy until the end of 2004, even though I have had little influence on the new version of ConAd.

 I will never forget the part played by Don Bain, technical manager of Maricopa, in all of this. It was he who recommended the initial purchase of the ConAd system to Dave Hudder back in early 2000, he who used ConAd to enable the expansion of Maricopa and build the U.S. reputation of ConAd, and he who left Maricopa for a time to help Command Alkon with initial marketing of ConAd. His written contribution to this text is appreciated, but it is negligible compared to his contribution to the reputation of the ConAd system. 

Andrew Travers continues to labor prodigiously as CEO of ConAd. Its future now depends on him as he rushes around the world promoting and  installing it. Unfortunately he has been far too busy to write a section of this book, much as he wanted to, and much as it would have been  appreciated. Perhaps he will write the next edition. Two other stalwarts, having contributed greatly, are no longer able to do so. Dan Leacy, the Australian equivalent of Don Bain, unfortunately passed away at an early age, and Michael Shallard retired at an even earlier age after a severe illness, depriving the system of its major source of computer expertise. I shall remember them.

he rapidly changing scene in concrete technology necessitates this fourth edition. Obviously I am aware of these changes, but being retired from active participation in concrete production and control, I have brought in two carefully selected coauthors in addition to obtaining input from many people I consider to be leading experts in their fields. The most fundamental change is the recognition that water to cement (w/c) ratio is not the best available criterion of quality and durability. 

This, combined with greenhouse gas and sustainability considerations, has caused cement replacement materials to be viewed in a new light. In the future, little, if any, concrete will be produced without at least one component of this large range of materials.

 Diminishing availability of natural sand conforming to preconceived ideal gradings has opened up the field for crusher fines, creating a new imperative to better understand their production and use. It is not surprising that higher strengths and higher heights of  pumpability are available, or that self-compacting concrete is becoming popular and there will always be new admixtures.

 One consequence of the greatly expanded range of materials is that theoretical mix design has essentially become only a tool for the education of new entrants to the field. Practical mixes in use will be the result of  feedback, adjustment, and trial and error—but the processes used to accomplish this will be very organised and precise rather than ad hoc.

 Ideal quality control (MMCQC), on the other hand, will not change from the ideal described in previous editions. The difference here is that the principles (and practice) set out many times over the years are at last showing signs of universal acceptance, even in the United States. Concrete production must be controlled by the producer.

The specification of concrete will become detailed and precise for other than very routine use. However, it will be detailed and precise in terms of required properties and performance rather than constituents. A specification for a major project is likely to be negotiated and agreed upon rather than imposed. We can look forward to a time when every significant.

producer will have a range of mixes with well-established properties from which a selection can be made. Durability is a major topic; having discarded w/c ratio as the best  criterion, a new criterion must be found. This needs to be in the form of a physical test because it must be applicable to a wide range of different   formulations. 

Although we are concerned with durability for an extended life, a test at as early an age as possible is needed to form part of the QC process. Although strength can no longer be regarded as a criterion of  durability, it retains its importance as a detector of change. A change point in strength is a change point in the mix quality and so may be the earliest way of detecting change in durability.

 However, having detected a change, its effect on durability cannot be established on strength grounds and a specific durability test is needed.