Ash Fill Research Articles

Effect of Underreamed Pervious Concrete Columns on Load-Carrying Capacity of Loose Cohesionless Soils

Weak confinement governs the bulging failure of granular columns. Pervious concrete columns have granular columns like drainage with stiffness of concrete column are thus independent of the confinement from the weak surrounding soil can be treated as an alternative solution. Moreover, it is well established that under-reaming bulb enhances the bearing resistance to the pile shaft. Therefore, the present experimental and analytical study investigates circular pervious concrete column (CPCC) and under-reamed pervious concrete column (UPCC) in improving the bearing capacity of loose pond ash fill. CPCC and UPCC are constructed in a model pond ash fill subjected to vertical loading. The load-carrying capacity, settlement failure mechanism, and consolidation parameters were examined. Theoretical analysis for evaluating the load-carrying improvement factor (LCF) with nondimensional parametric variation of area replacement ratio (Ra), underreamed bulb ratio (Br), and length ratio of the column (RL) was also done. Efficacy of CPCC was also numerically studied (Plaxis 3D). Experimental results show that the vertical settlement is reduced by 52.8% with CPCC and UPCC. UPCC renders higher load-carrying capacity than CPCC. Both CPCC and UPCC undergo deformation at depth of 4D during failure. For the same area replacement ratio (Ra), the experimental and theoretically computed values are found in good agreement. The rate of consolidation is reduced from 53 to 23 days by using CPCC signifying its drainage potential.

Consolidation and bearing capacity studies on solid waste ash fill by using hybrid granular piles

Consolidation and bearing capacity studies on solid waste ash fill by using hybrid granular piles

Optimal arrangement of geogrids in road embankment using different fill materials

Due to rapid growth of industrialization and urbanization, the slope stability of embankments constructed with locally available materials became the most important area for geotechnical engineers. The stability of these embankments can be improved by adopting geogrid reinforcement with native soil or by replacing the embankment with Pond Ash. The present study is on the slope stability analysis of a road embankment with crest width of 8 m, side slopes of 2H:1V and height 5 m resting on 10 m thick c-ϕ soil. The purpose of this study is to analyse the normal fill and pond ash embankments with reinforced and unreinforced conditions using Slope/w module in Geostudio 2021. The Mohr-coulomb material is used to model the soils and Morgenstern-Price method is used to find out the factor of safety (FOS) for a critical slip surface. Geogrids are placed at different layers in normal and pond ash embankments and the optimal arrangement is found out. It is found that the factor of safety is increased by 69.5% when the normal fill is replaced with pond ash as the angle of internal friction is higher for pond ash. The optimal arrangement of geogrid at 1st and 4th layers in combination with pond ash fill embankment gives a highest factor of safety of 2.928 and in case of normal fill, the highest factor of safety is 2.184.

Observed behaviour of old railway embankments formed of ash and dumped clay fill

Many old railway embankments were originally formed from loose dumped clay fill on which ash fill was subsequently placed to maintain the track level. These have required considerable maintenance, primarily because of embankment movements. They are mostly covered by trees, and tree roots are present in both fills. As part of a London Underground Limited programme of stabilisation works in the 1990s, two embankments were instrumented to investigate the mechanisms and causes of movement. Lateral deformations, settlements and pore pressures were measured. This paper describes the instrumentation and monitoring techniques that were adopted and presents the findings from the study. It was found that non-recoverable seasonal movements occur in both the ash fill and the clay fill. The former occur in dry weather, particularly in the slopes of the embankments crests, due to ash particle mobility under train loading when the ash is dry. Clay fill deformations are exacerbated by the presence of tree roots. Movements correlate well with climate, as quantified by the soil moisture deficit determined from meteorological data. Establishing the mechanisms of movement within these ash–clay fill embankments helped to guide the design of stabilising measures.

Load-Settlement Behavior of Concrete Debris Pile in Fly Ash Fill

Abstract This study addresses the problem of disposal and effective reuse of waste material, fly ash, and construction concrete debris in order to find an optimized solution for their bulk disposal...

Model tests on geosynthetic-encased construction concrete debris column in fly ash fill

Providing geosynthetic-encased stone columns is a commonly adopted technique to improve the load-carrying capacity and reduce settlements in weak fills. Addressing the geo-environmental aspect, two different waste materials, i.e., fly ash and concrete debris, have been used for the sustainable environmental management. This paper presents a series of model tests results carried on single unencased and geosynthetic-encased construction concrete debris (CCD) column installed in fly ash fill under short-term loading. Footing size was taken as twice the column diameter for 25% area replacement ratio. Two sizes of columns, 50 mm and 75 mm diameter, have been used for both end-bearing and floating end conditions. The results were analyzed in terms of bearing capacity ratio and settlement ratio. Experimental model tests clearly show that circumferential geosynthetic encasement greatly influences the ultimate load-carrying capacity of CCD column and reduces settlement of treated fly ash fill bed.

Evolution of pore structure in blended systems

In this study, the effect of SCM in the cement paste was isolated by using ternary systems combining Portland cement, quartz and SCM. The results show clear differences in how the hydrates from the reaction of clinker, slag and fly ash fill space. The reaction of slag is more efficient than that of fly ash in modifying the porosity. Our results indicate that Portland cement (PC), slag and fly ash reactions are limited at later ages by the lack of water-filled capillary pores. The higher the space available, with increasing the water/solids ratio, the later the reaction is limited. This explains the lower degree of reaction of SCM in blended systems at high replacement levels.

Large model footing load test on reinforced coal ash slope

The use of coal ash in structural fills to support footings and pavements in low lying areas can be one of the cost effective and environmentally friendly solutions to disposal problems related to coal ash, because wastes can be consumed in large quantities in such applications. The difficulty with this ash disposal solution is that the structural fills may not meet the foundation requirements for bearing capacity and settlement, especially when footings and pavements are constructed near the crest of the ash fill slope. Inclusion of geosynthetic reinforcements as horizontal sheets within the fill may be one of the most viable techniques for improving the load bearing capacity of the coal ash slope. Most technical information available in the literature on the load bearing capacity of footings resting on the slopes is based on small scale laboratory model tests; hence practicing engineers cannot generally adopt the information realistically. Therefore, in the present study as described in this paper, large scale model footing tests were conducted in the laboratory to find out the effectiveness of use of single and multilayer geosynthetic reinforcements in improving the load bearing capacity of coal ash slope. The results were found to be encouraging and they may have practical applications.

Load-Bearing Capacity of the Footing Resting on a Reinforced Fly Ash Slope

In several parts of the world, disposal of waste materials such as fly ash is a great problem. Application of waste materials as structural fills in foundations is one of the best solutions to disposal problems, because wastes can be used in large volumes in such applications. There may be difficulty due to poor load-bearing capacity of fly ash, especially when footing rests on the top of the fly ash fill slope. Inclusion of polymeric reinforcements as horizontal sheets within the fill may be one of the most viable solutions to improving the load-bearing capacity of reinforced fly ash slope, and it is particularly important for the situations where foundations need to be located either on the top of a slope or on slope itself. The present work is aimed at investigating the efficacy of a single layer of reinforcement in improving the load-bearing capacity when it gets incorporated within the body of a model fly ash embankment slope. An increase in load bearing capacity due to the incorporation of reinforcement in the model slope was found by conducting laboratory tests. Experimental results were compared by numerical values obtained using software GEO5 and PLAXIS.

Deformation Modulus of Fly Ash Modified with Lime and Gypsum

Deformation modulus of fly ash is one of the most important mechanical properties generally used in different design problems and also as an input parameter to sophisticated numerical techniques employed to assess the response of different structures resting on fly ash fill or embankment made of fly ash. Deformation modulus is usually expressed in terms of compressive strength. This paper presents the deformation modulus of fly ash modified with lime alone or in combination with gypsum at different strain levels. The values of deformation modulus obtained from both unconfined compression test and unconsolidated undrained triaxial test results are presented herein. The specimens for unconfined compression test and for undrained triaxial tests were cured up to 90 and 28 days, respectively. The effects of addition of lime (4–10%) and gypsum (0.5 and 1.0%) on the deformation modulus of class F fly ash are highlighted. With addition of lime and gypsum, the class F fly ash achieved the deformation modulus in the range of 190 MPa in UCS test and up to 300 MPa in triaxial test specimens tested under all round pressure of 0.4 MPa. Based on the present test results empirical relationships are developed to estimate deformation modulus of modified fly ash from unconfined compressive strength and relationships between initial tangent modulus and secant modulus at different strain levels are also developed.

At the Drive-In Volcano, and: Candy Necklace, and: The Traveling Lizard

At the Drive-In Volcano, and: Candy Necklace, and: The Traveling Lizard Aimee Nezhukumatathil (bio) At the Drive-In Volcano St. Lucia I am a very different wife.Sulfur & ash fill my noseuntil both nostrils are beige,my hands hot & webbedwith steam. My husband urgesme closer to the centerof the steaming calderafor a picture until I am upagainst the rail. Our guidetells us of a rasta manwho once fell in-& survived. His entire bodyturned smooth as a candle.Come with me, Husband.Put down your backpack,your camera-let usbe remarried in fire.One by one the stars go out.Even in this darkness,there is so much light. [End Page 144] Candy Necklace Each piece of chalky wafer breaksmy heart. I adore these pastel chips strung on the thinnest of elastics. I holdthem in my mouth. I drool little rings down my lips and when I tryto talk and giggle there is a catch in the throat-a catch when the elasticsnaps and the sizzle of candy spills on tile like a drop of orange sauce on a hot grill.Winter now and drunk flies knock against my window for just one more drinkof light, or to sink into fruit juice left in a glass overnight. I chew off all the tiny pinkrings, then the blues, the yellows, and leave all the white: a sad excuse for pearlsat this age. We have sticky necks sticky hands and when I slide the candy-an abacus around my neck-I count the times you thought of me today-or was ithow many times I thought of you? I place the silly truck-stop rings you offered meunder my tongue. My neck is still sticky, still collects-but the candy necklaceI wear tonight is all the rings you gave [End Page 145] my phone and I didn't answer. NowI can afford even peacock pearls clasped in a wild gold latch but I have no moneyfor his steps his boot his taste. The Traveling Lizard The honeymoon is overand we find a dead lizardin our luggage. An anole, actually-its neckflesh swollen and dry, like a single papery bougainvillea flower pinned to its tiny neck. Anoles creeped the walls of our island bungalow but all seemed so quick, so skittish.Even the slightest movementof mosquito netting sent themscurrying behind a picture frame. So how to explain its presence here in western New York, home of the chicken wing, the crazed football fans? Perhaps it too wanted to travel far, escape rainy seasonand the dumb huzz of mosquito, wantedto know what it was like to perch on a singledry berry and snatch a crunchy fly. [End Page 146] Aimee Nezhukumatathil Aimee Nezhukumatathil is the author of At the Drive-In Volcano and Miracle Fruit, both from Tupelo Press. She is a professor of English at the State University of New York-Fredonia. Copyright © 2007 University of Nebraska Press

Characterization of an F-Class Fly Ash for Use as a Road Sub-base

An F-class fly ash was tested in the laboratory for its physical and mechanical properties for use as a road sub-base in portions of a 2.1-mi (3.4-km) truck by-pass route in east-central Illinois. The testing showed that the fly ash would perform adequately and behave predictably as a road sub-base. Construction of the by-pass route started in early June 2002 and was finished in early September 2002. No unanticipated delays were encountered, and the performance of the fly ash fill exceeded expectations. Hopefully, these positive results will promote other projects around the country to use by-products of coal combustion products, especially fly ash, as suitable fill materials. This project was a co-operative development and demonstration effort among the Office of Coal Development and Marketing (OCDM) of the Illinois Department of Commerce and Economic Opportunity (IDCEO), Southern Illinois University at Carbondale (SIUC), Morgan County Highway Department (MCHD), Illinois Department of Transportation (IDOT), AmerenCIPS, and the Morgan County Regional Planning Commission. These agencies provided both funding and matching funds to carry this project to completion. The by-pass route was designed to move truck traffic around the southern and eastern sides of the small town of Meredosia, Illinois. One problem the proposed by-pass project encountered was the source of construction materials for the sub-base fill. The project needed an additional 77,000 yd.3 (59,000 m3) of fill for the sub-base. Because of the geology in the Meredosia area, one source of material for the sub-base was sand from a borrow pit. Several other possible sources were investigated, but most were too expensive for the limited budget. The alternative chosen was to use ponded F-class fly ash from the AmerenCIPS Meredosia power plant adjacent to the truck by-pass route. The first task of the project was to determine the physical and material properties …

Cone Resistance of Compacted Ash Fill

Abstract Coal ash is a granular byproduct of the combustion of coal in coal-fired thermal power plants. The compacted ash is frequently used as a structural fill material. Standard geotechnical investigation methods used for natural soils have revealed inconsistencies when extended to ash fills. The characterization of ash shows morphological dissimilarity with natural soils. It is observed that several groupings of in situ density and stress level lead to similar penetration resistance in coal ash. Thus, the correlations reliable for soils may have questionable interpretations of blow count or measured cone resistance in coal ash. The static cone penetration test results analyzed at various combinations of stress level and relative density indicated the need for a new scheme for interpretation of behavior of ash fills on the basis of relative dilatancy of the ash. The resistance to penetration of the standard cone was interpreted at varying depths on ash fill compacted at varying relative densities. Correlations are suggested to estimate bearing capacity and settlement characteristics of coal ash on the basis of cone penetration test results for direct geotechnical design.

Percolation of clay liners of ash landfills in short and long time perspectives.

Top covers of waste landfills conventionally contain a drain layer over a 1(low-permeable clay liner usually containing smectite minerals. The rate of percolation of the clay liner, which may require tens of years to become water-saturated, determines the downward transport of ions released from the underlying waste to and through the bottom clay liner. The percolation rate is controlled by the composition and density of the tipper liner, which should be as tight as possible. This implies a high density and therefore a high swelling potential which must be moderated by proper design. The bottom clay liner is a less effective and reliable barrier since cation exchange will increase the hydraulic conductivity and cause a significant rise in percolation rate and risk of chemical attack by the percolate. The top liner will undergo very moderate strain if the ash fill is effectively compacted and undergoes little self-compaction. Processes that may cause degradation are freezing and drying and require proper design. In this paper the authors examine the performance of ash-fills isolated by clay liners and conclude that the most important issue is to design and construct the top liner to be as impermeable as possible paying less attention to the tightness of the bottom layer.

Collapse Behavior of Coal Ash

The paper describes an investigation carried out to examine the factors influencing collapse settlement of the compacted coal ash due to wetting. The ashes produced by the coal fired thermal power plants are stored as a high mound in the disposal dump. Some of the ash dumps and ash fill structures wetted under certain conditions of loading may exhibit collapse. Attempts have been made to correlate the ash characteristics and the specific placement parameters such as ash type, soluble content, degree of compaction, overconsolidation ratio, moisture content, and stress level at wetting with collapse. This was based largely on the oedometer and partly on the model and the field test results. 378 single oedometer tests were conducted to obtain the collapse potential. The collapse potential was correlated with the mean size of the ash. The favorable pressure, moisture, fines, compaction, soluble substance, and prestressing decrease the collapse potential of an ash fill. The collapsible and the noncollapsible ashes were identified by the results of oedometer test and laboratory model test. Normally, if the collapse potential in the oedometer is more than 0.01, the collapse of soils may occur in the field. However, the model test demonstrated this to be an unconservative criterion. A value of 0.0075 at 80% degree of compaction was found appropriate for the ashes examined. The paper explains the technique of field test performed at the controlled densities. The field test confirmed incidence of collapse on a rising water table for a collapsible ash.

Radon level reduction in two kindergartens in Slovenia.

Remedial actions were carried out in two kindergartens with average heating season radon concentrations of about 2,000 Bq m-3. The first kindergarten is built on sedimentary gravel and the second one on fly ash and cinder fill. In both cases, radon accumulated in a sub-floor channel (service tunnel). The channels were opened at both ends. Natural ventilation of the tunnels did not produce a sufficient reduction in radon concentration. A fan was mounted in one kindergarten to ventilate the channel for 20 min three times each day, thus reducing radon levels to an acceptable value.

REINFORCED EARTH TRIAL STRUCTURE FOR DEWSBURY RING ROAD.

A full-scale trial reinforced soil retaining wall was constructed prior to the building of Dewsbury ring road. The trial structure was used to assess the suitability of reinforced earth structures built on soft soil constructed using pulverized fuel ash (PFA) fill reinforced with polymeric reinforcement. During the trial, drainage and construction techniques were evaluated and wall movements and reinforcement strains recorded. The corrosiveness of PFA was studied. As a result of the trial the use of PFA as a structural fill in reinforced soil was accepted by the Department of Transport, and the polymeric grid material used was awarded an Agrement certificate for use in reinforced soil structurs designed for a life of 120 years. (A)

Santo Domingo de Los Colorados--A New Pioneer Zone in Ecuador

N many parts of Latin America new pioneer zones are appearing. In each case pioneer settlement has followed the construction of a highway. The postwar road building programs, supported by loans from a variety of sources, are opening up new areas which were previously unoccupied or only thinly occupied. Unfortunately, not all these new pioneer zones have been examined in advance by land classification experts, nor have they been properly surveyed. In some cases disaster can be predicted with confidence. In other cases the outcome is not at all certain. In January, 1959, the authors of this paper were able to examine one of these new pioneer areas in Ecuador, and to gather the information for this report. Santo Domingo de los Colorados is located at the western base of the Andes, about 45 miles in a straight line to the west of Quito, and a little less than one hundred miles southeast of Esmeraldas (Fig. 1). The low country to the west of the Andes in Ecuador is made up of a mixture of low hills and flat valley lowlands. Where rivers emerge from the high Andes, they bring down vast quantities of volcanic material, and this material is accumulated in huge fans along the western base of the mountains. One of these fans directly east of Guayaquil has the effect of confining the drainage of the whole Guayas Basin in one narrow channel as it finds its way out to the Gulf of Guayaquil. Farther to the north there are other similar fans. Santo Domingo is situated near the apex of a fan that spreads out from where the Rio Toachi emerges from the Western Cordillera. Where this fan borders the mountains opposite the end of the Toachi Valley the elevation is about 1800 feet above sea level. Santo Domingo is also just about on the divide between two major drainage basins. The Rio Toachi itself is a tributary of the Rio Blanco which in turn is a tributary of the Rio Esmeraldas. Just to the north is the Rio Guaillabamba, another tributary of the Esmeraldas, the headwaters of which are eroding the ash fill of the Quito Basin. Where the Rio Toachi crosses the fan slope, it has cut a flat-floored trench which is between one and two hundred feet below the surface of the fan. The Santo Domingo settlements are on the undissected fan slope, several miles west of the trench of the Rio Toachi (Fig. 2). Draining this fan