The Implementation of Fly Ash as a Stabilization Device in Clay Soils PDF Download
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Author: Robert J. Glazewski
Publisher:
ISBN:
Category :
Languages : en
Pages : 202
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Author: Robert J. Glazewski
Publisher:
ISBN:
Category :
Languages : en
Pages : 202
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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.
Author:
Publisher:
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: Terrel, Epps, and Associates
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages : 380
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Author: Kevan D. Sharp
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 136
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Book Description
"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: Ignacio Romero
Publisher:
ISBN:
Category : Fly ash
Languages : en
Pages : 48
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Author: Irem Zeynep Yildirim
Publisher: Joint Transportation Research Program
ISBN: 9781622602698
Category : Transportation
Languages : en
Pages : 38
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In Indiana, the steelmaking industries and power plants generate large quantities of steel slag, blast furnace slag and fly ash every year. The excess of these underutilized industrial by-products are stockpiled and eventually landfilled at disposal sites. Use of steel slag, fly ash and blast furnace slag in road applications, such as in subgrade stabilization projects, can be a cost-effective alternative to lime stabilization in some cases. In addition, use of large quantities of these underutilized industrial by-products in these types of applications helps to reduce the need for new disposal sites and to conserve natural resources. The main objectives of this research were to evaluate the feasibility of using soil-steel slag-Class-C fly ash and soil-steel slag-blast furnace slag mixtures in subgrade applications and to implement the selected mixture as a subgrade material in a road construction project of INDOT. In order to achieve these goals, in situ clayey soils, collected from a prospective implementation site, were characterized through a series of laboratory tests which included specific gravity, grain size distribution, Atterberg limits, compaction and unconfined compressive strength. Two types of steel slag mixtures were evaluated for use in subgrade stabilization applications: i) steel slag-Class-C fly ash mixtures and ii) steel slag-blast furnace slag mixtures. The mechanical properties of soil-5% steel slag-5% Class-C fly ash, soil-7% steel slag-3% Class-C fly ash, soil-8% steel slag-2% Class-C fly ash, and soil-7% steel slag-3% blast furnace slag mixtures were determined through compaction and unconfined compression tests. CBR swelling tests were also performed to assess the swelling potential of the mixtures. The optimum moisture content and maximum dry unit weight of the in situ clayey soil samples were 13% and 18.56 kN/m3 (118.2 pcf), respectively. Based on the results of the long-term CBR swelling tests, the maximum swelling strain of the compacted soil samples was approximately 0.41 %. The average unconfined compressive strength of the in situ soil samples was 282.9 kPa (41 psi). Unconfined compressive strength tests performed on various mixtures at different times indicated the occurrence of stronger cementitious reactions in the soil-steel slag-Class-C fly ash mixtures than in the soil-steel slag-blast furnace slag mixtures. The two-day and seven-day unconfined compressive strength of the compacted soil-7% steel slag-3% Class-C fly ash mixture were 820 kPa (119 psi) and 886 kPa (128 psi), respectively. The maximum 1-D swelling strain of the soil-7% steel slag-3% Class-C fly ash mixture was 0.13 %. The soil-7% steel slag-3% Class-C fly ash mixture was selected as the most suitable and cost-effective subgrade material for the implementation project. The implementation project for the soil-steel slag-Class-C fly ash mixture was located at the intersection of 109th Avenue and I-65, near Crown Point, Indiana. The pre-mixed 7% steel slag-3% Class-C fly ash mixture was used to stabilize the in situ subgrade soils of some sections of the I-65 ramps located in the SW and NW quadrants of the intersection of 109th Avenue and I-65. Field compaction quality control was done by performing DCPTs and nuclear gauge tests. Cracks or signs of distress were not observed on the subgrade before base course and concrete placement. The soil-steel slag-Class-C fly ash stabilized subgrade performed satisfactorily.
Author: Hector A. Acosta
Publisher:
ISBN:
Category :
Languages : en
Pages : 306
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Author: Tianhong Mu
Publisher:
ISBN:
Category :
Languages : en
Pages : 372
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In this study, coal combustion by-products mainly fly ash, commercial fibers and a natural fiber i.e., human hair were applied to stabilize the kaolinite clay and local Carbondale soil i.e., silty clay. During recent decades, the demand for infrastructures such as highways, buildings, bridges have greatly increased, especially in the areas where population was growing rapidly. All of these infrastructures need a stable foundation and in many cases the original land couldn't sustain the load from the infrastructures. In such situation, soil stabilization becomes an essential step before the foundation is laid. There are several ways to stabilize soil, viz., mechanical stabilization, chemical stabilization, stabilization by inclusion and confinement etc. It has been reported by several researchers that fly ash and fibers can significantly improve the strength of soil. Fly ash and natural fiber i.e., human hair are both waste materials, and commercial fibers are low-cost compared to other soil stabilizers. In this study, class C fly ash was used to stabilize commercially available clay i.e., Kaolinite; while both human hair and commercially available fibers (e.g., glass fiber and plastic fiber) were used to stabilize Kaolinite and Carbondale local soil. Based on this research, it could be concluded that the class C fly ash can improve the Unconfined Compressive Strength (UCS) value of Kaolinite clay significantly; fibers also could increase the UCS value of both Kaolinite and Carbondale local soil. While, the tensile strength of Kaolinite and Carbondale local soil sometimes increases or decreases depending on the percentages of fiber content used into Kaolinite and Carbondale local soil. The current research on soil stabilization by fly ash and those fibers may provide a new possibility for soil stabilization.
Author: John Michael Pitt
Publisher:
ISBN:
Category : Fly ash
Languages : en
Pages : 196
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Previous Iowa DOT sponsored research has shown that some Class C fly ashes are ementitious (because calcium is combined as calcium aluminates) while other Class C ashes containing similar amounts of elemental calcium are not (1). Fly ashes from modern power plants in Iowa contain significant amounts of calcium in their glassy phases, regardless of their cementitious properties. The present research was based on these findings and on the hyphothesis that: attack of the amorphous phase of high calcium fly ash could be initiated with trace additives, thus making calcium available for formation of useful calcium-silicate cements. Phase I research was devoted to finding potential additives through a screening process; the likely chemicals were tested with fly ashes representative of the cementitious and non-cementitious ashes available in the state. Ammonium phosphate, a fertilizer, was found to produce 3,600 psi cement with cementitious Neal #4 fly ash; this strength is roughly equivalent to that of portland cement, but at about one-third the cost. Neal #2 fly ash, a slightly cementitious Class C, was found to respond best with ammonium nitrate; through the additive, a near-zero strength material was transformed into a 1,200 psi cement. The second research phase was directed to optimimizing trace additive concentrations, defining the behavior of the resulting cements, evaluating more comprehensively the fly ashes available in Iowa, and explaining the cement formation mechanisms of the most promising trace additives. X-ray diffraction data demonstrate that both amorphous and crystalline hydrates of chemically enhanced fly ash differ from those of unaltered fly ash hydrates. Calciumaluminum- silicate hydrates were formed, rather than the expected (and hypothesized) calcium-silicate hydrates. These new reaction products explain the observed strength enhancement. The final phase concentrated on laboratory application of the chemically-enhanced fly ash cements to road base stabilization. Emphasis was placed on use of marginal aggregates, such as limestone crusher fines and unprocessed blow sand. The nature of the chemically modified fly ash cements led to an evaluation of fine grained soil stabilization where a wide range of materials, defined by plasticity index, could be stabilized. Parameters used for evaluation included strength, compaction requirements, set time, and frost resistance.
