This page contains a Flash digital edition of a book.
 


It’s important to note that companies like CalStar are also required to meet ASTM’s C618 specification which mandates acceptable trace levels of metals and toxins in the actual fly ash which is being used in their building products.


Fly Ash Facts
While some environmentalists are labeling the concrete industry’s recycling of fly ash as “greenwashing,” the fact is that substituting fly ash for cement, from a sustainability perspective, is very significant.


“A good rule of thumb is that manufacturing a pound of cement generates a pound of CO2, and worldwide cement production accounts for 7% of all CO2 emitted,” explains Kren.


Consequently, when a fourth to a third of the cement in concrete is swapped out with fly ash, this makes quite a dent in the embodied energy and CO2 emissions created by concrete production.


In fact, the American Concrete Institute reports that, in 2007, cement production’s CO2 emissions were reduced by 15 million tons, thanks to fly ash.


CalStar’s patented process actually takes this even further as fly ash fully replaces cement in their products, which are also not fired in an energy-intensive kiln. As a result, the company reports an 85% reduction in energy and CO2 emissions for their products. It’s easy to see why so many companies have put so much emphasis on fly ash as a “green” path forward.


Fly ash is also known to increase the concrete’s durability, so “longer service life means that much less material and energy will be used to repair, rebuild or replace constructions,” adds Kren.


Furthermore, fly ash enhances concrete performance—including increased strength, improved sulfate resistance, decreased permeability, a reduction in the water/cement ratio required, and enhancement of pumpability and workability of the concrete, according to Shepherd.


Of course, the other reality that needs to be dealt with is the sheer volume of fly ash which is produced by coal combustion every year.


“In North America, the burning of coal for power generates about a half a cubic foot per person per year,” explains Bruce King, P.E., director, Ecological Building Network, San Rafael, Calif., and author of the book, “Making Better Concrete: Guidelines to Using Fly Ash for Higher Quality, Eco-Friendly Structures.”


“That’s a bucket of ash in the name of every man, woman and child in America, every year,” he says. “Whether we like it or not, we have to do something with it.”


 


ANNUAL FLY ASH PRODUCTION AND USE
Tracking the production and percentage use of fly ash since 1966, this American Coal Ash Association graphic shows a general upward trend.

Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76