Making Better Concrete
"Making Better Concrete: Guidelines to Using Flay Ash for Higher Quality, Eco-Friendly Structures"
This book by Bruce King is a good addition to the library of anyone who
wants to understand the theme of using fly ash in concrete. Such
understanding is important for people who take the decisions about what
products to use. Pozzolans in concrete could have a tremendous impact
on reducing the environmental footprint of cement. Worldwide, the
production of Portland cement alone accounts for 6-8% of
human-generated CO2 (depending on whom you ask). So here, in a single
industry, lies the opportunity to slow the very alarming trend toward
global warming.
Making better concrete: Guidelines to using fly ash for higher quality, eco-friendly structures
Kathryn Pozak
It was a pleasure indeed to read the new book, Making Better
Concrete, by Bruce King. As a lay person who has been exposed to the
theme of alternative concrete for about a decade, I finally have a
clearer grasp of what the lofty scientists are talking about.
The starting point for this article will be the last chapter, which
presents the big picture. It refers to the effects of fly ash as so
many, and so positive, that senior figures in the world of concrete
have recently stated that concrete without fly ash belongs in a museum.
Many reasons for using fly ash are global, environmental, or societal
in nature. Attention is drawn to the production of Portland cement that
puts about a ton of carbon dioxide (CO2, a primary greenhouse gas) in
the atmosphere for every ton of cement produced – roughly half a ton
from the fuel used to cook the raw limestone, and half a ton from the
calcinations of the limestone. Worldwide, the production of Portland
cement alone accounts for 6-8% of human-generated CO2 (depending on
whom you ask). So here, in a single industry, lies the opportunity to
slow the very alarming trend toward global warming.
On the more positive side he refers to one authority who states that for every ton of fly ash used (to replace Portland cement)
- Enough energy is saved to provide electricity to an average American home for 24 days
- The landfill space conserved equals 455 days of solid waste produced by the average American.
- The reduction in CO2 emissions equals 2 months of emissions from an automobile.”
In Making Better Concrete, Guidelines to Using Fly Ash for Higher
Quality, Eco-Friendly Structure, the author has presented a scientific
overview in simple language. Peppered with drawings, provocative
quotations, statistics and graphics, and explanatory appendices, the
book also depicts examples of buildings throughout the world where fly
ash has been used as a replacement for traditional Portland
cement. He clearly states that it is not an academic paper,
rather a guidebook.
The chapters themselves attest to this, beginning with A Short History
of Fly Ash and Pozzolans in Concrete, then providing definitions in
Chapter 2, What is Fly Ash? What are Pozzolans? Once that is understood
he passes on to How do Fly Ash and Pozzolans affect concrete? Here he
focusesupon its effects on fresh concrete, on plastic concretes and on
hardened concrete.
Chapter 4 on Design Considerations treats the importance of ensuring
that “every stakeholder in the construction is educated and aware of
the ramifications, potential problems, and benefits of its use.” This
involves listening to concerns and suggestions. He confronts
specifications by stressing a “Call for the concrete performance
you really need”. He draws attention to the importance of design, mix,
place and test trial batches ahead of time by referring to the
“carpenter´s axiom: measure twice, cut once).
Use of HFAC to counteract common problems such as “heat of hydration in
mass concrete, increase resistance to corrosion and degradation caused
by high-sulfate soils, reactive aggregates, salt air or water, or
caustic chemical (e.g. dairy plants, wineries, and gas station,” opens
the door to seeing some of its applications. The importance of
expertise is underlined in “Check for availability of fly ash – and
expert help”. It goes on to “Pay attention during construction” and
“Check for exposure to deicing salts.” It finishes with “Evaluate
conditions: a rough guide to how easy or hard it may be to use HFAC in
different applications.”
Chapter 5 on Construction Considerations begins with an “Ouch!” where
Bruce reveals that “More than a few times in my career as an engineer,
I have come to a job site the day after a concrete pour to find the
contractor eagerly stripping formwork from walls because the sun can
then shine on it and dry it out and make it cure faster.” He uses
the word “Ouch” both because the premature exposure to sun has an
opposite and terrible effect, because an otherwise competent builder
understand so little about a material he works with every day.
His final provocation: “In fact, if you don´t plan to control water
content and cure the concrete well, throw this book away; it will do
you no good.”
This is even more reason to ensure that this book reaches decision-makers and builders.