 TABLE
of CONTENTS Chapter 1 A Short History of Fly Ash and Pozzolans in Concrete Chapter 2 What is Fly Ash? What are Pozzolans? A.
Pozzolans defined by source and standards organizations B. Pozzolans defined by reactivity
and availability
The basic pozzolanic reaction The transition zone A. Effects of fly ash on fresh
concrete A. Get the whole team on board Chapter 5 Construction Considerations A.
Controling the water content Chapter 6 Why Use Fly Ash? The big picture Appendices Appendix A: Sample Mix Designs Appendix B: Resources Appendix C: High Fly
Ash Concrete and LEED® Introduction Ninety percent
of this game is half mental. The
only thing new in the world is the history you don't know Coal fly ash is an abundant industrial waste product that happens to be high in reactive silica, and thus an excellent pozzolan (which we'll define in Chapter 2). For this simple reason it is rapidly becoming a common ingredient in concrete all over the world; it is already present to some degree in half the concrete poured in the US. The reasons for this are many, as will be described in the pages to follow. Of particular interest to the industry is the idea of not just adding fly ash to known concrete mixes, but using large quantities to replace 30%, 50%, or more of the portland cement-the glue-in a concrete mix. Most of the reasons for using fly ash in any proportion are practical, such as increasing strength and durability, decreasing heat of hydration, and decreasing permeability. Those reasons alone make the idea of high fly ash concrete (HFAC) worth considering, but there are many global economic, health, and environmental concerns that make HFAC even more attractive and compelling. The use of fly ash as a performance-enhancing ingredient in concrete is one of the most outstanding examples of industrial ecology-i.e., making effective use of waste resources, and ultimately eliminating the concept of waste altogether. In fact, given the huge (and growing) volume of concrete production worldwide, the potential for effectively using fly ash (and other common industrial by-products) makes it one of the key components of a global industrial ecology. There is, not surprisingly, disagreement among fly ash experts. Some will argue for higher or lower portions of fly ash than you will find presented in this book. The term HFAC is generally interpreted as referring to concrete in which fly ash replaces about 50% of the cement. However, in some cases 40% or 10% will be more appropriate, and in others 100% replacement is possible. Some experts will argue that 30% replacement is the most one should ever use, while others argue that you won't get the greatest benefits of HFAC until you get up to or over 40 or 50% replacement. The right figure for your project in your location will depend on many things, as will be reviewed in the pages to come. This book is not an academic treatise. It will provide a cursory look at the history, economics, and performance effects of fly ash in concrete, but mainly is intended to provide practical guidelines for those who want to use it. Here you will find some basic do's and don'ts for ready-mix suppliers, concrete contractors, engineers, and others involved in concrete construction. Those who want more detailed material on any subject-and there's plenty available-can find references in the back of this book. Using HFAC is not rocket science, but neither is it obvious or intuitive. Now, however, you can now learn from the experience of others before using it yourself.
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