Class F Fine Fly Ash

Sheu, T. C.; Quo, L.W.; Kuo, Shu-Lung

doi:10.1557/proc-178-159

Cited by 4 publications

(2 citation statements)

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“…200 sieve (0.075 mm). Sheu et al (1990) reported that most fly ash investigated passed the No. 400 sieve (0.0325 mm) with only 6% of fly ash being retained on the No.…”

Section: Grain Size Distributionmentioning

confidence: 99%

Determination of Ash Mixture Properties and Construction of Test Embankment , Part A

Kim¹,

Yoon²,

Balunaini³

2006

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Prepared in cooperation with the Indiana Department of Transportation. AbstractClass F fly ash and bottom ash are solid residue byproducts produced by coal-burning plants. They are usually disposed off with a typical disposal rate of 80 % fly ash and 20 % bottom ash. To maximize the use of the coal ash, and thus significantly reduce the disposal problem that electric utility companies and our society in general face, the direct use of ponded or landfilled ash that is composed of high proportions of fly ash would be desirable. However, a general understanding of the behavior of high volume fly ash mixtures is needed. Although there have been investigations into the properties of separated single types of ash, the studies of the fly/bottom ash mixtures, especially with high fly ash contents, are very limited.Representative samples of class F fly ash and bottom ash were collected from two utility plants in Indiana and a series of extensive laboratory tests were conducted to obtain the mechanical properties of the mixture. Since the mechanical properties of ash mixtures are dependent on the mixture proportions, the investigations evaluate fly/bottom ash mixtures with different mixture ratios (with Fly ash contents of 50%, 75%, and 100%). The results obtained are merged with other considerations relevant to embankment design and construction and used to develop guidelines on coal ash utilization in highway embankments. In order to examine suitable fly/bottom ash mixture compositions and embankment geometries, slope stability analyses were performed on ash embankments with different geometries using the different properties of the ash mixtures with different mixture ratios. The limit equilibrium method was used for the stability analyses. Additionally, the corrosion potential to metal structures, which are commonly included in highway construction, is examined by performing corrosivity tests on the ash mixtures. Key WordsFly ash, bottom ash, disposal, mixtures, embankments, highway construction. Distribution StatementNo restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161 affect their specific gravity, particle strength, and consequently other mechanical properties to varying degrees. The impact of these morphological characteristics on mechanical properties tends to be constant for a given ash source, but vary between different ash sources.2) Fly/bottom ash mixtures (with mixture ratios ranging from 50% to 100% fly ash content) exhibit relatively well-defined moisture-density relationships, and the relationships vary with mixture ratios. As the fly ash content increases from 50% to 100% (i.e., as bottom ash content decreases from 50% to zero), w opt increases, and γ d,max decreases gradually. The values of γ d,max for compacted ash mixtures tend to vary greatly from plant to plant, due to a relatively wide range of specific gravity values from plant to plant. However, overall, the values of γ d,max of ash are lower than those of typi...

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“…200 sieve (0.075 mm). Sheu et al (1990) reported that most fly ash investigated passed the No. 400 sieve (0.0325 mm) with only 6% of fly ash being retained on the No.…”

Section: Grain Size Distributionmentioning

confidence: 99%

Determination of Ash Mixture Properties and Construction of Test Embankment , Part A

Kim¹,

Yoon²,

Balunaini³

2006

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“…Some particles may be rounded or rodshaped (Huang 1990). Slags from lignite and sub-bituminous coals tend to be more vesicular than slags of the eastern bituminous coal (Huang 1990 (Sheu et al 1990) the crushing process, the particle shapes become more angular. (Huang 1990 (Huang 1990 (Ke 1990 (Huang 1990 Nevertheless, due to the complex pore structure of bottom ash aggregates, irregular response to compaction may be produced (Huang 1990 (Huang 1990 (Huang 1990 (Huang 1990).…”

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confidence: 99%

Building Embankments of Fly/Bottom Ash Mixtures

Lovell¹,

Salgado²

1997

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This research investigates the engineering properties of mixtures of bottom ash and Class F fly ash relevant to their utilization in highway embankment construction. The research included ash samples from two major power plants in Indiana that disposed of their ash differently. The first power plant disposes of the bottom ash and fly ash separately and hence explicit mixtures were synthetically formed and tested. The second power plant disposes of the bottom and fly ash together in a common location and hence they become mixed, forming implicit mixtures. The implicit mixtures were processed using a wet method, the Shallow Slurry Deposition Method, to produce homogeneous samples for the research.Characterization of the ash included grain size analysis, specific gravity, maximum and minimum density, in addition to microscopic investigation.The investigation of compaction behavior of a range of explicit and implicit mixtures was conducted at the standard energy effort. The effects of changing the mixture composition on the maximum dry unit weight and optimum moisture content were established. In order to study the effect of changing the moisture content on penetration resistance, surface penetration tests were performed on the compacted samples. Beyond the optimum moisture content, the penetration resistance of the samples drops significantly, which suggests that the compaction can better be conducted dry of optimum. To control the compaction appropriately, the degree of compaction of a sample must be determined using a compaction curve for a mixture of similar gradation.Consolidated drained triaxial tests were performed on a range of explicit and implicit mixtures at three levels of confining pressures. For each mixture tested, two groups of samples were prepared, one at a relative compaction (R%) of 90% and the other at 95%. The results indicate that the drained shear strength depends on the mixture composition, the degree of compaction, and the confining pressure. Adequate shear strength and volumetric behavior was observed for the samples compacted at 95%. It They are then flushed with water and driven through the disposal pipes. As a result of the crushing process, the particle shapes become more angular. (Figure 3.1). Moreover, samples from the shallow streams formed between the discharge locations and the disposal pond contain fine materials ( Figure, To form an explicit mixture for compaction or triaxial testing, the bottom ash was composed then mixed with fly ash. The bottom ash fraction in the mixture was formed by composing the ash fractions to obtain a gradation similar to the average gradation of the two large bottom ash samples (Section 3.1.3.1). A specific quantity of fly ash was mixed with a predefined quantity of bottom ash to form an explicit mixture of known fly ash content. The fly and bottom ash are nuxed slowly by hand at first and then a specified water quantity was sprayed gradually while the mixing was continued in a mortar mixer (Figure 3.4) Table 3.2). The gra...

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