38    GEOTECHNICAL CHARACTERIZATION OF
SEVERAL COAL COMBUSTION BY-PRODUCTS
Min Zhang, Graduate Research Assistant
Aiwen Feng, Graduate Research Assistant
Rick Deschamps, Assistant Professor
School of Civil Engineering
Purdue University
West Lafayette, Indiana 47907
INTRODUCTION
The generation of coal combustion by-products (CCBPs) by utility companies and private industries is increasing and the trend is expected to continue in the foreseeable future. Over 71 million tons of ash was produced throughout the United States in 1985. but only a small portion of
CCBPs was utilized in any form.1 In the state of Indiana, more than six million tons of CCBPs
are generated each year with only about 11% of these materials being utilized in a constructive
manner, while the remaining materials are typically ponded on site or disposed of in landfills.
CCBPs have been used in a broad range of applications, including: production of low strength
concrete and brick, soil stabilization, agricultural lime, pollution control, and carbon recovery.
Most of these applications use a relatively small volume of by-product. A viable large volume
application for the CCBPs is as a structural fill in roadway embankment construction. Fly ash
and bottom ash have been successfully used as construction materials in many embankment projects.2-3 The mineralogical and physical characteristics of CCBPs vary between power plants due
to a number of factors such as coal source, plant combustion characteristics, and pre-processing
and post-processing operations. Systematic laboratory and field testing is necessary to assess the
physical and mechanical properties of specific CCBPs.
A large roadway embankment is currently under construction using several CCBPs as structural fill. The project site is located on the Purdue University campus in West Lafayette, Indiana.
A vicinity map indicating the location of the project site is shown in Figure 1. A paved road will
be constructed on the crest of this embankment to extend Russell Street, providing convenient
access to the southern expansion of Purdue University's campus. The embankment is approximately 700 feet in length, with a maximum crest height of about 40 feet. The crest will be about
50 feet wide and a maximum base width of 250 feet. The project site and test embankment location is illustrated in Figure 2.
A comprehensive geotechnical laboratory testing and field monitoring program is being implemented to evaluate the physical and mechanical characteristics of various CCBPs and to predict
the performance of the embankment during and after construction. Preliminary geotechnical laboratory testing results are presented in this paper.
COAL COMBUSTION BY-PRODUCTS
The project is utilizing CCBPs generated by the Wade Utility Plant of Purdue University and
A. E. Staley Manufacturing Company of Lafayette, Indiana. Six different coal combustion byproducts are being implemented in this project (see Table I). Although fly ash has been used previously as a structural fill in embankment construction,4-5 little information is available pertinent
to the geotechnical characteristics of the fluidized bed combustion ashes and the stoker ash.
50th Purdue Industrial Waste Conference Proceedings. 1995. Ann Arbor Press, Inc.. Chelsea. Michigan 48118.
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