Weathering Effects on the Hydraulic Conductivity of Fly Ash Stabilized Soil Used in Levee and Embankment Construction PDF Download
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Author: Engin Mumcu
Publisher:
ISBN:
Category : Embankments
Languages : en
Pages : 152
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Author: Engin Mumcu
Publisher:
ISBN:
Category : Embankments
Languages : en
Pages : 152
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Author: Mustafa Yaykiran
Publisher:
ISBN:
Category : Erosion
Languages : en
Pages : 176
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Author: Chester W. Jones
Publisher:
ISBN:
Category : Fly ash
Languages : en
Pages : 34
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Author: Rafal Gaciarz
Publisher:
ISBN:
Category : Fly ash
Languages : en
Pages : 57
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Book Description
Soil Stabilization occupies an important role in all Civil Engineering works. Now with the scarcity of good building sites, engineers are forced to use the available sites, modify their geotechnical properties and build facilities. In these direction different methods of soil stabilization offers them inexpensive but efficient solutions. Soil stabilization is the process of increasing strength and bearing capacity of soils either by mechanical or chemical methods. Stabilization also eliminates or decreases settlements, hydraulic conductivity and swell and shrinkage potential. The mechanical method of stabilization involves the change of gradation of the soil and densifying the soil by mechanical methods such as rollers. Chemical stabilization involves altering the properties by adding cement, lime or any other cementations material. In this study an attempt has made to investigate the efficacy of class C Fly Ash to stabilize silty soils. Varying proportions of fly ash was added and determined the basic geotechnical properties such as, specific gravity, plasticity, compaction characteristics, unconfined compression strength and stress-strain modulus. It has been observed that the addition of fly ash did not alter significantly the plasticity characteristics of the soil. Standard Proctor and Harvard Miniature Compaction Tests revealed that maximum dry density increases with increasing fly ash content and optimum moisture contents decreased with increasing in ash contents. Unconfined compression tests were conducted on compacted specimens corresponding water contents of optimum moisture contents (OMC), OMC-2%, and OMC+2%. It has been observed that the unconfined compressive strength (qu) and consequently the undrained shear strength (SuĈ ) which is half the unconfined compressive strength increased moderately with increasing fly ash content for all the 3 moisture content conditions. However, the stress-strain modulus decreased with increasing ash content. The modulus and the unconfined compressive strengths of soil-fly ash mixtures can be expressed by an approximate formula: E=15 to 100qu Where, E = Stress-Strain modulus (either Tangent or Secant Modulus) qu = Unconfined compressive strength. From the analysis of the results of this study, it appears that fly ash is not an effective stabilizer to stabilize silty soils. This may be due to the fact that both silt particles and fly-ash particles have approximately same size. This might result in poor gradation that is deficient in particle interlocking in silt-fly ash mixtures. Another important property required for effective stabilization is plasticity. Unlike lime, fly ash is a low or non-plastic material and is not effective in binding the soil particles together.
Author: Zachary Guy Thomas
Publisher:
ISBN:
Category :
Languages : en
Pages : 444
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Research was initiated to evaluate the engineering properties and to observe the short and long-term behavior of soil stabilized with self-cementing fly ash. Typically Iowa soils have low strength due to high fines content. Five Iowa soils ranging from ML to CH were used in this study as well as self-cementing fly ash from eight Iowa power plants. Fly ash addition had a profound effect on the compaction characteristics of the soils. The influences of fly ash content, moisture content, and compaction delay on compressive strength were observed for samples molded with ISU 2-in x 2-in apparatus as well as standard 4-inch diameter Proctor equipment. Long-term strength gain was evaluated for samples that were over 2.5 years old. California Bearing Ration (CBR) of fine-grained soils was also increased substantially with the addition of fly ash. Strength gain was also tested for samples cured in various environments. Freeze-thaw and wet-dry durability of soils were increased and reductions in plasticity characteristics were observed with fly ash addition. The morphology of soil-fly ash mixtures was studied as well as the clay mineralogy of the soils used in the study. In addition to the study of soil-fly ash mixtures, previous ISU research involving hydrated and conditioned fly ash was continued. The research utilized four sources of hydrated fly ash (HFA) and two sources of conditioned fly ash (CFA) from Iowa. Moisture content, curing temperature and time all had an impact on the strength gain of HFA and CFA. Shear strength parameter values for these materials were also determined. In addition to evaluating the strength of HFA and CFA alone, these two types of materials were also tested as soil stabilizers. The final part of research was to use the information determined in the previous tests to develop construction guidelines. Three construction guidelines were developed for use in Iowa. Two of these guidelines described the procedures for using HFA and CFA as select fill under pavement structures, while the third set of guidelines was developed for constructing sections of self-cementing fly ash stabilized soil.
Author:
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ISBN:
Category : Fly ash
Languages : en
Pages : 182
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Soil treated with self-cementing fly ash is increasingly being used in Iowa to stabilize pavement subgrades, but without a complete understanding of the short- and long-term behavior. To develop a broader understanding of fly ash engineering properties, mixtures of five different soil types, ranging from ML to CH, and several different fly ash sources (including hydrated and conditioned fly ashes) were evaluated.
Author:
Publisher:
ISBN:
Category : Fly ash
Languages : en
Pages : 82
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Book Description
Soil treated with self-cementing fly ash is increasingly being used in Iowa to stabilize pavement subgrades, but without a complete understanding of the short- and long-term behavior. To develop a broader understanding of fly ash engineering properties, mixtures of five different soil types, ranging from ML to CH, and several different fly ash sources (including hydrated and conditioned fly ashes) were evaluated.
Author: Kevan D. Sharp
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 136
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"Fly Ash for Soil Improvement provides civil and geotechnical engineers with a contemporary review of the beneficial uses of fly ash for both general construction purposes and for waste containment/soil stabilization. Peer-reviewed papers describe the use of self-cementing fly ashes as a soil stabilization agent; fly ash stabilization of tropical Hawaiian soils, south Texas soils, and industrial wastes; enzyme-enhanced stabilization; lime sludge amended fly ash; calcareous expansive clays; and engineering properties of a clay modified by fly ash and slag."--BOOK JACKET.Title Summary field provided by Blackwell North America, Inc. All Rights Reserved
Author: William F. Barstis
Publisher:
ISBN:
Category : Fly ash
Languages : en
Pages : 350
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Author: Khelifa Saiki
Publisher:
ISBN:
Category : Fly ash
Languages : en
Pages : 136
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Book Description
Soil stabilization is a technique to improve soil properties. Currently many methods are available to stabilize soils and improve their engineering properties. The soil type,soilstructure and economic factors govern the decision to select an appropriate single or a combination of two or more methods. The stabilization of soil can be accomplished by adding cementing material, or some other chemical material to change engineering property of soil. After this addition of stabilizer to soil, engineering properties of soil such as increases strength, load bearing capacity, durability, workability and etc. Stabilization can be achieved by mechanically mixing the natural soil and stabilizer together to reach desired improvement. There are many types of additives which can be used for stabilization. There are Portland cement, lime and fly ash. This project focuses on the effectiveness of fly ash as stabilizer. Fly ash is a waste material produced by combustion of pulverized coal in thermal power plants. Since many years fly ash has been used as a construction material. Thermal power plants produce two kinds of fly ash; class F and class C. Class F fly ash is more popular than class C and contains less amount of lime. Class C fly ash has a large amount of lime, (more than 20%), so it has a better cementing characteristic. Class F ash are used in Portland cement production. While class C fly ash is more suitable in soil stabilization because of high percentage of lime and its cementing characteristics. In this project we used fly ash of class C as soil stabilizer, by adding a varying proportions of fly ash we determined the basic geotechnical properties such as, specific gravity, plasticity, compaction characteristics, unconfined compression strength and stress-strain modulus. Addition of small percentage of fly ash (about 3 %) decrease plasticity characteristics of clay. Beyond this percentage, addition of fly- ash tends to increase the plasticity. Harvard Miniature Compaction Tests indicate that maximum dry density increases with increasing fly ash content and optimum moisture contents decrease with increase in ash contents. Unconfined compressive tests were conducted on compacted specimens corresponding water content of optimum moisture contents (OMC), OMC-2%, and OMC +2%. The unconfined compressive strength (qu) and consequently the undrained shear strength (Su) which is half the unconfined compressive strength show a steep increase at 6% fly ash, beyond that increased moderately with increasing fly ash content for all the 3 moisture content conditions. However, the stress-strain moduli with increases with increasing fly ash contents. However it appears that there is no correlation between the modulus of elasticity ant the unconfined compressive strength. The result analysis of this study, it appears that fly ash class "C" is not an effective stabilizer to stabilize clay. This may be due to the fact that both clay particles and fly-ash particle have approximately same size. This might result in poor gradation that is deficient in particle interlocking in clay-fly ash mixtures. Another important property required for effective stabilization is plasticity. Unlike Lime, fly ash is a low non- plastic material and is not effective in binding the soil particles together.
