page 251 |
Previous | 1 of 6 | Next |
|
|
Loading content ...
27 COMPACTION OF FLY AND BOTTOM ASH MIXTURES Ahmed Korayem "Karim," Doctoral Candidate Rodrigo Salgado, Assistant Professor C. W. Lovi'll. Professor School of Civil Engineering, Purdue University West Lafayette, Indiana 47906 INTRODUCTION Fly ash and bottom ash constitute the major components of coal combustion by-products. Nearly three million tons of these materials are produced annually by coal burning power plants in Indiana. The major part of these materials is disposed of as a form of waste. Utilization of these materials in embankment construction, besides reducing the disposal problem, can save natural soils for more efficient utilization. This chapter describes a laboratory study that investigates the behavior of explicit mixtures of fly and bottom ash in compaction. Samples of bottom ash and Class F fly ash were collected. Mixtures of fly ash and bottom ash in known proportions were developed in the laboratory. The behaviors of these materials in compaction were studied and the effects of increasing the fly ash contents in the mixtures were investigated. Increasing the fly ash content from zero to an optimum value led to reducing the optimum moisture content as well as increasing the maximum dry density of the compacted mixture. Increasing the fly ash content further leads to reduction of the maximum dry density and increasing the optimum moisture contents. The results are especially important for controlling the compaction of ash mixtures in highway embankments. BACKGROUND Nearly 23% of the United State's electricity is generated by coal burning power plants.1 Approximately 85 million tons of coal combustion by products (CCBPs) are produced annually.2 While parts of these CCBPs have found their way to utilization, the majority are still disposed of as a form of waste. Fly ash and bottom ash represent the major part of the CCBPs. Fly ash and bottom ash represent the noncombustible portion in addition to the unburned portion of the coal. Utilization of compacted single types of ash, whether fly or bottom ash, in embankment construction was reported in the literature.3-4 However, the largest portions of the fly and bottom ash are currently disposed of in the form of mixtures in disposal ponds.5 The utilization of these mixtures in embankment construction has been delayed because of concerns about the control of their compaction on the site, and the behavior of the compacted mixtures in the embankment body. Fly/Bottom Ash Generation and Disposal Class F fly ash is generated when bituminous or anthracite coal is burned. It consists typically of spherical fine particles that are carried by the combustion hot gases through the top of the combustion chamber. The ash is then separated from the gases by some form of collection system such as electrostatic precipitators. The ash is then collected and either stored in silos in a dry condition or pumped hydraulically to a pond. Fly ash particles sizes can typically be found in the range of 75 microns to a fraction of a micron. More than 90% by weight is typically smaller than 45 microns. This size range is comparable to the silt size range. Commonly, fly ash is either dis- 51st Purdue Industrial Waste Conference Proceedings. 1996. Ann Arbor Press, Inc., Chelsea, Michigan 48118. Printed in U.S.A. 251
Object Description
Purdue Identification Number | ETRIWC199627 |
Title | Compaction of fly and bottom ash mixtures |
Author |
Korayem, Ahmed Salgado. Rodrigo Lovell, C. W. |
Date of Original | 1996 |
Conference Title | Proceedings of the 51st Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://e-archives.lib.purdue.edu/u?/engext,46351 |
Extent of Original | p. 251-256 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Date Digitized | 2009-10-27 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 251 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | 27 COMPACTION OF FLY AND BOTTOM ASH MIXTURES Ahmed Korayem "Karim," Doctoral Candidate Rodrigo Salgado, Assistant Professor C. W. Lovi'll. Professor School of Civil Engineering, Purdue University West Lafayette, Indiana 47906 INTRODUCTION Fly ash and bottom ash constitute the major components of coal combustion by-products. Nearly three million tons of these materials are produced annually by coal burning power plants in Indiana. The major part of these materials is disposed of as a form of waste. Utilization of these materials in embankment construction, besides reducing the disposal problem, can save natural soils for more efficient utilization. This chapter describes a laboratory study that investigates the behavior of explicit mixtures of fly and bottom ash in compaction. Samples of bottom ash and Class F fly ash were collected. Mixtures of fly ash and bottom ash in known proportions were developed in the laboratory. The behaviors of these materials in compaction were studied and the effects of increasing the fly ash contents in the mixtures were investigated. Increasing the fly ash content from zero to an optimum value led to reducing the optimum moisture content as well as increasing the maximum dry density of the compacted mixture. Increasing the fly ash content further leads to reduction of the maximum dry density and increasing the optimum moisture contents. The results are especially important for controlling the compaction of ash mixtures in highway embankments. BACKGROUND Nearly 23% of the United State's electricity is generated by coal burning power plants.1 Approximately 85 million tons of coal combustion by products (CCBPs) are produced annually.2 While parts of these CCBPs have found their way to utilization, the majority are still disposed of as a form of waste. Fly ash and bottom ash represent the major part of the CCBPs. Fly ash and bottom ash represent the noncombustible portion in addition to the unburned portion of the coal. Utilization of compacted single types of ash, whether fly or bottom ash, in embankment construction was reported in the literature.3-4 However, the largest portions of the fly and bottom ash are currently disposed of in the form of mixtures in disposal ponds.5 The utilization of these mixtures in embankment construction has been delayed because of concerns about the control of their compaction on the site, and the behavior of the compacted mixtures in the embankment body. Fly/Bottom Ash Generation and Disposal Class F fly ash is generated when bituminous or anthracite coal is burned. It consists typically of spherical fine particles that are carried by the combustion hot gases through the top of the combustion chamber. The ash is then separated from the gases by some form of collection system such as electrostatic precipitators. The ash is then collected and either stored in silos in a dry condition or pumped hydraulically to a pond. Fly ash particles sizes can typically be found in the range of 75 microns to a fraction of a micron. More than 90% by weight is typically smaller than 45 microns. This size range is comparable to the silt size range. Commonly, fly ash is either dis- 51st Purdue Industrial Waste Conference Proceedings. 1996. Ann Arbor Press, Inc., Chelsea, Michigan 48118. Printed in U.S.A. 251 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Tags
Comments
Post a Comment for page 251