A review of the multi-component utilisation of coal fly ash

Scientific approaches to pile design have advanced enormously in recent decades and yet, still, the most fundamental aspect of pile design—that of estimating the axial capacity—relies heavily upon empirical correlations. Improvements have been made in identifying the processes that occur within the critical zone of soil immediately surrounding the pile, but quantification of the changes in stress and fabric is not straightforward. This paper addresses the degree of confidence we can now place (a) on the conceptual and analytical frameworks for estimating pile capacity, and (b) on the quantitative parameters required to achieve a design. The discussion is restricted to driven piles in clays and siliceous sands, with particular attention given to extrapolating from design approaches derived for closed-ended piles of relatively small diameter to the large-diameter open-ended piles that are used routinely in the offshore industry. From a practical viewpoint, we need design approaches that minimise sensitivity...

Science and empiricism in pile foundation design

Progressive utilisation prospects of coal fly ash: A review

This report presents information on the characterization of cementitiously stabilized layers and the properties that influence pavement performance. It also contains recommended performance-related procedures for characterizing these layers and performance-prediction models for incorporation into the mechanistic–empirical pavement analysis methods. Individual chapters highlight pavement distresses of hot-mix asphalt pavements and concrete pavements, laboratory tests and model development, and model calibration. The material contained in the report will be of immediate interest to state materials, pavement, and construction engineers and others involved in the different aspects of pavement design and construction.

Characterization of Cementitiously Stabilized Layers for Use in Pavement Design and Analysis

Solid wastes, fly ash, and bottom ash are generated from coal and biomass combustion. Fly ash is mainly composed of various metal oxides and possesses higher thermal stability. Utilization of fly ash for other industrial applications provides a cost-effective and environmentally friendly way of recycling this solid waste, significantly reducing its environmental effects. On the one hand, due to the higher stability of its major component, aluminosilicates, fly ash could be employed as catalyst support by impregnation of other active components for various reactions. On the other hand, other chemical compounds in fly ash such as Fe2O3 could also provide an active component making fly ash a catalyst for some reactions. In this paper, physicochemical properties of fly ash and its applications for heterogeneous catalysis as a catalyst support or catalyst in a variety of catalytic reactions were reviewed. Fly-ash-supported catalysts have shown good catalytic activities for H2 production, deSOx, deNOx, hydrocar...

Application of solid ash based catalysts in heterogeneous catalysis.

Class F fly ash and bottom ash are the solid residue byproducts produced by coal-burning electric utilities. They are usually disposed of together as a waste in utility disposal sites with a typical disposal rate of 80% fly ash and 20% bottom ash. Direct use of these materials in construction projects consuming large volumes of materials, such as highway embankment construction, not only provides a promising solution to the disposal problem, but also an economic alternative to the use of traditional materials. Representative samples of class F fly and bottom ash were collected from two utility power plants in Indiana and tested for their mechanical properties (compaction, permeability, strength, stiffness, and compressibility). Three mixtures of fly and bottom ash with different mixture ratios (i.e., 50, 75, and 100% fly ash content by weight) were prepared for testing. Test results indicated that ash mixtures compare favorably with conventional granular materials.

Geotechnical Properties of Fly and Bottom Ash Mixtures for Use in Highway Embankments

Both the driving response and static bearing capacity of open-ended piles are affected by the soil plug that forms inside the pile during pile driving. In order to investigate the effect of the soil plug on the static and dynamic response of an open-ended pile and the load capacity of pipe piles in general, field pile load tests were performed on instrumented open- and closed-ended piles driven into sand. For the open-ended pile, the soil plug length was continuously measured during pile driving, allowing calculation of the incremental filling ratio for the pile. The cumulative hammer blow count for the open-ended pile was 16% lower than for the closed-ended pile. The limit unit shaft resistance and the limit unit base resistance of the open-ended pile were 51 and 32% lower than the corresponding values for the closed-ended pile. It was also observed, for the open-ended pile, that the unit soil plug resistance was only about 28% of the unit annulus resistance, and that the average unit frictional resistance between the soil plug and the inner surface of the open-ended pile was 36% higher than its unit outside shaft resistance.

Behavior of Open- and Closed-Ended Piles Driven into Sands

Construction of a test embankment using a sand–tire shred mixture as fill material

Evaluation of the mechanical properties of class-F fly ash.

Load and resistance factor design ~LRFD! is the standard structural design practice. In order for foundation design to be consistent with current structural design practice, the use of the same loads, load factors, and load combinations would be required. In this paper, we review the load factors presented in various LRFD codes from the United States, Canada, and Europe. A simple first-order second-moment ~FOSM! reliability analysis is presented to determine appropriate ranges for the values of the load factors. These values are compared with those proposed in the codes. The comparisons between the analysis and the codes show that the values of load factors given in the codes generally fall within ranges consistent with the results of the FOSM analysis. However, it would be desirable for the successful development and adoption of the geotechnical component of LRFD codes to have uniformity of load-factor values across different codes for the loads that are common for virtually all civil structures.

Bumjoo Kim

Papers

Geotechnical Properties of Fly and Bottom Ash Mixtures for Use in Highway Embankments

Behavior of Open- and Closed-Ended Piles Driven into Sands

Construction of a test embankment using a sand–tire shred mixture as fill material

Evaluation of the mechanical properties of class-F fly ash.

Assessment of current load factors for use in geotechnical load and resistance factor design