Showing papers on "Fly ash published in 1988"
TL;DR: Long-term leaching studies predict that fly ash will lose substantial amounts of soluble salts over time, but simulation models predict that the loss of trace elements from fly ash deposits through leaching will be very slow.
233 citations
TL;DR: In this paper, a thermogravimetric test was conducted on hardened cement pastes containing fly ash and the results showed that the water content of these pastes can be divided into two components: water held by calcium hydroxide, and water held in other reaction products.
179 citations
TL;DR: The literature is reviewed concerning the effects of incinerator operating parameters on emissions and the presence of metals and organics in incinerator quench water and in leachates from ash disposed in landfills, as well as their toxicity to fish.
130 citations
TL;DR: In this article, the effects of chemical attack on portland cement mortar from internal and external sulfate sources were compared with respect to expansion and strength development and substantial differences exist between the two types of sulfate attack.
125 citations
TL;DR: In this article, the ability of fly ash to remove Omega Chrome Red ME (a chrome dye, mostly used in textile industries) from water has been studied, and it has been found that low adsorbate concentration, small particle size of adsorbent, low temperature, and acidic pH of the medium favor the removal of chrome dye from aqueous solutions.
Abstract: The ability of fly ash to remove Omega Chrome Red ME (a chrome dye, mostly used in textile industries) from water has been studied. It has been found that low adsorbate concentration, small particle size of adsorbent, low temperature, and acidic pH of the medium favor the removal of chrome dye from aqueous solutions. The dynamics of adsorbate transport from bulk to the solid phase has been studied at different temperatures in light of the adsorption of dye on the outer surface as well as diffusion within the pores of fly ash. The applicability of Langmuir isotherm suggests the formation of monolayer coverage of dye molecules on the outer interface of adsorbent. The thermodynamics of chrome dye-fly ash system indicates spontaneous and exothermic nature of the process. The pronounced removal of chrome dye in the acidic range may be due to the association of dye anions with the positively charged surface of the adsorbent.
123 citations
TL;DR: In this paper, the porosity of plain Portland cement pastes and those containing silica fume or fly ash was assessed by several methods on plain and blended Portland Cement pastes.
114 citations
TL;DR: In this article, fly ash and bottom ash obtained from coal-fired electric power generating stations can be used as alternatives to natural materials for the construction of structural fills and the engineering properties of coal ash pertinent to its use in structural fills are discussed.
Abstract: Fly ash and bottom ash obtained from coal-fired electric power generating stations can be used as alternatives to natural materials for the construction of structural fills. The engineering properties of coal ash pertinent to its use in structural fills are discussed. Four case studies of coal ash structural fills are presented. The performance of these fills was monitored during and after construction. These cases demonstrate that the physical behavior of fly ash is similar to that of silt and that it can be handled with similar methods. Groundwater monitoring data from existing fly ash fills are presented to show the impact that ash leachate migrating into the groundwater regime has on water quality. Results of long-term corrosion studies are presented to show that metals buried in ash, used in such structures as culverts, cable ducts, guard rails and streetlights, are not adversely affected. Ash leachate was found not to be detrimental to good-quality concrete structures. Key words: fly ash, fill, comp...
112 citations
TL;DR: In this article, the capacity of peat to treat two different landfill leachates was determined, and the efficiency of treatment was evaluated as a function of factors important for developing filter design criteria.
Abstract: In this investigation, the capacity of peat to treat two different landfill leachates was determined. Freundlich isotherms showed that, for the tested metals (Cd, Cr, Cu, and Pb), an increased time of contact increased the level of adsorption over the entire range of influent values studied. In addition, metal interaction may play an important role in the adsorption of metals from leachate, as the various metal ions compete for the available adsorption sites on the peat. Column studies using two leachates, one from a municipal refuse fill (Al, Ca, Cd, Fe, Mg, Na, and Pb), and one from a fill which receives mainly oil and fly ash (Al, Ca, Cr, Fe, Mg, Mn, Na, Pb, and V), were conducted to establish design parameters for full-scale design. The efficiency of treatment was evaluated as a function of factors important for developing filter design criteria. Further considerations were given to filter longevity and ease of replacement, as well as for the ultimate disposal of the peat from the filters. For the municipal leachate a compaction density of 0.12 g mL−1 gave the best results as clogging occurred at higher densities, whereas 0.18 g mL−1 provided the best removal for the industrial leachate. While peat is incapable of adequately removing metals to acceptable levels for direct discharge, peat can provide substantial removal as a pretreatment process at low hydraulic loadings. Desorption of up to 50% was found when deionized water was applied to spent columns so ultimate disposal of the peat would require a dry environment.
90 citations
Patent•
08 Aug 1988
TL;DR: A synthetic Class C fly ash can replace about 25-50% by weight of portland cement in conventional formulations with coarse and fine aggregate for general purpose concrete and particularly ready-mix concrete with comparable compressive strength and like properties.
Abstract: A synthetic Class C fly ash results from a substantially homogeneous blend of about 40-60% by weight of a Class F fly ash and about 60-40% by weight of cement kiln dust (CKD). This new fly ash can replace about 25-50% by weight of portland cement in conventional formulations with coarse and fine aggregate for making general purpose concrete and particularly ready-mix concrete with comparable compressive strength and like properties.
83 citations
TL;DR: The impact of blending agents on the internal environment of cement systems is assessed by chemical analysis of the pore fluid in cured blends in this article, which shows that the short-term behaviour of PFA blends is complicated by the presence of soluble alkali.
72 citations
Patent•
14 Nov 1988
TL;DR: A hydraulic cement is formed from a Class C fly ash, an alkali metal activator, and citric acid as mentioned in this paper, which is particularly useful in producing mortar and concrete compositions that achieve high strength in a short time.
Abstract: A hydraulic cement is formed from a Class C fly ash, an alkali metal activator, and citric acid. Mortar and concrete compositions can be prepared with this hydraulic cement. The cement is particularly useful in producing mortar and concrete compositions that achieve high strengths in a short time, in particular, a mortar having a strength of at least 2500 psi in 24 hours, when cured at room temperature.
TL;DR: In this paper, a series of eight concrete mixtures involving twelve batches, each 0.06 m3 in volume, were made at a water-to-cementitious materials ratio of 0.32 ± 0.01.
Abstract: This paper gives results of an investigation undertaken to develop additional data on mechanical properties, and freezing and thawing resistance of high-volume Class F fly ash concrete made with ASTM Types I and III cements. A series of eight concrete mixtures involving twelve batches, each 0.06 m3 in volume, were made at a water-to-cementitious materials ratio of 0.32 ± 0.01. The fly ash-to-(fly ash + cement) ratio was 0.56. The cement content of the mixtures was 154 kg/m3. All mixtures were air-entrained and superplasticized. The mixtures incorporated Type I and Type III cements, various combinations of as-received fly ash, beneficiated fly ash, and condensed silica fume. From the test results, it is concluded that high-volume fly ash concrete has excellent mechanical properties and satisfactory resistance to repeated cycles of freezing and thawing. The use of ASTM Type III cement appears to be essential when high strengths at early ages are required. For concretes made with ASTM Type I cement, the use of beneficiated fly ash, and beneficiated fly ash and condensed silica fume, does little to enhance the properties of concrete compared with “as received” fly ash. For concrete made with ASTM Type III cement, the benefits of using beneficiated Class F fly ash and condensed silica fume are not clear.
TL;DR: In this paper, lead, zinc, cadmium and copper from effluents of battery industry, fertiliser industry, zinc electrolysis, sulphuric acid production and flotation plant by precipitation, adsorption and reverse osmosis were investigated.
Abstract: Ramoval of lead, zinc, cadmium and copper from effluents of battery industry, fertiliser industry, zinc electrolysis, sulphuric acid production and flotation plant by precipitation, adsorption and reverse osmosis were investigated. The rejection 91–98% of heavy metals from treated effluents by sulphide precipitation was achieved. The fly ash of power plant was used in pretreatment step for reverse osmosis process. Treatment of the chemically clarified effluents by cellulose acetate—coal membranes shows the high removal efficiency of investigated metals.
TL;DR: In this article, the effect of fly ash on the compressive strength development of the hardened concrete was evaluated, and it was concluded that the use of a large amount of fly-ash, as replacement for both cement and sand, is highly beneficial.
TL;DR: In this paper, the weathered residues retrieved after fly ash leaching were analyzed for major constituents by atomic absorption spectrophotometry and trace elements by instrumental neutron activation analysis, and the characteristics of the residues ranged from highly leached acidified material, from which many constituent elements had been mobilized, to minimally leached alkaline material containing accumulations of newly formed secondary minerals.
TL;DR: The results of a 3-year study on the properties of concrete containing fly ash are presented in this article, where both fresh and hardened properties are reported of concrete made using Type 1 cement, river gravel, natural sand, and fly ashes from several sources.
Abstract: The results of a 3-year study on the properties of concrete containing fly ash are presented. Both the fresh and hardened properties are reported of concrete made using Type 1 cement, river gravel, natural sand, and fly ashes from several sources. The mixtures were proportioned to have similar slump and a constant cementitious content by weight. It is shown that concrete containing fly ash can be proportioned having equal strength properties and adequate durability when a suitable ASTM C 618 Class C or F fly ash is used. Test data on over 1600 laboratory and field specimens tested for freeze-thaw resistance, flexural strength, compressive strength, creep, shrinkage, and abrasion resistance are presented. Fly ash contents ranging from 0 to 35 percent by weight of portland cement were used with both Class C and Class F fly ashes. Guidelines for the selection of materials and their proportions for producing concrete containing fly ash to meet existing highway specifications for concrete are presented.
TL;DR: In this paper, the authors examined the effect of slurrying conditions on solids reactivity and found that the solids formed in slurries containing 10 to 100 ppM of dissolved calcium were up to 40% more reactive than those formed in slurries containing less than 10 ppM or more than 100 pM.
Abstract: To examine the effect of slurrying conditions upon solids reactivity, slurries of fly ash and Ca(OH)/sub 2/ were monitored for dissolved metal concentrations with atomic absorption spectrophotometry The solids produced were dried and tested for reactivity towards SO/sub 2/ in a packed bed reactor at bag filter conditions The solids formed in slurries containing 10 to 100 ppM of dissolved calcium were up to 40% more reactive than the solids formed in slurries containing less than 10 ppM or more than 100 ppM of dissolved calcium The dissolved calcium concentration was affected by NaOH concentration, fly ash loading (g fly ashg Ca(OH)/sub 2/), slurry temperature, fly ash type, and the presence of CaSO/sub 3/ /center dot/ 05 H/sub 2/O High calcium fly ash could be activated to remove 13 mmol SO/sub 2/g sorbent which is almost as reactive as the solids prepared by slurrying low calcium fly ash with Ca(OH)/sub 2/ at a fly ash loading of 4 (144 mmol SO/sub 2/g) Low and medium calcium fly ashes, under identical slurrying conditions removed only 033 mmol SO/sub 2/g sorbent
TL;DR: Etude de l'influence de la dimension des particules de cendre, du pH sur l'adsorption du bore sur les cendres volantes en milieu aqueux.
Abstract: Etude de l'influence de la dimension des particules de cendre, du pH sur l'adsorption du bore sur les cendres volantes en milieu aqueux
Patent•
29 Sep 1988TL;DR: In this article, a waste solidification composition comprising hydraulic cement, fly ash and fumed silica material is provided, along with a method of solidifying agglomerations of solid and liquid waste materials and a method for disposing of waste materials such as drilling muds and cuttings that result from the drilling of an oil and gas well.
Abstract: A waste solidification composition comprising hydraulic cement, fly ash and fumed silica material is provided. Also provided are a method of solidifying agglomerations of solid and liquid waste materials and a method of disposing of waste materials such as drilling muds and cuttings that result from the drilling of an oil and gas well.
TL;DR: In this paper, the authors used selective dissolution, TG, XRD, analytical electron microscopy and Ca(OH)2 determinations on both whole samples and dissolution residues to determine changes in the mineralogy of Portland cements.
TL;DR: A limited investigation of the influence of 35% replacement of one OPC by two pfa's upon rate and depth of carbonation, strength development and water retention of concrete cubes is described in this paper.
Abstract: Synopsis A limited investigation of the influence of 35% replacement of one OPC by two pfa's upon rate and depth of carbonation, strength development and water retention of concrete cubes is descri...
Patent•
26 Oct 1988
TL;DR: In this paper, a bag filter is used to produce a clean gas stream that is recycled to compressors or power recovery turbines and a concentrated syngas stream blowdown from which additional solids are subsequently removed.
Abstract: A method and apparatus for removal of fine particulate fly ash at high temperature and pressures using a bag filter which produces a clean gas stream that is recycled to compressors or power recovery turbines and a concentrated syngas stream blowdown from which additional solids are subsequently removed.
30 Jun 1988
TL;DR: In this article, the mutagenic activity of fly ash and emission gases from municipal waste incinerators was investigated and a negative relationship was obtained for complete combustion and a positive one for incomplete combustion.
Abstract: We have investigated the mutagenic activity of fly ash and emission gases from municipal waste incinerators. A negative relationship was obtained for complete combustion and a positive one for incomplete combustion. There were more mutagens in emission gas than in precipitated fly ash and residual ash. The total revertants per minute for emission gas discharged from the incinerator to the environment corresponded to those for 1700–3000 motor vehicle exhausts. Various polycyclic aromatic hydrocarbons (PAHs) were detected as a result of incomplete combustion and most of the mutagenic substances were released into the environment from the municipal incinerator as volatile emission gases. Urban waste incinerators are the main source of environmental pollution which results from incomplete combustion.
TL;DR: In this article, several 102-mm cubes were cast from cement paste, mortar, and concrete mixes containing ordinary portland cement and suspended in a channel containing either a 1 or 3 percent nominal solution of continuously flowing sulfuric acid.
Abstract: Several 102-mm cubes were cast from cement paste, mortar, and concrete mixes containing ordinary portland cement and suspended in a channel containing either a 1 or 3 percent nominal solution of continuously flowing sulfuric acid. The parameters investigated included cement content, water-cement ratio (W/C), additions of pulverized fuel ash (PFA), polyvinyl alcohol (PVA), a latex (styrene butadiene), and a high-range water-reducing admixture (HRWA). The changes in weight with time for each cube were determined continuously up to a maximum exposure period of 93 days. The results indicated that the rate of deterioration of the cubes increased with an increase in cement content, w/c, or acid concentration. The addition of polyvinyl alcohol appeared to enhance the resistance and integrity of the cubes.
TL;DR: In this article, the effect of pH on leaching of selected elements from Ca-rich (Type C) power plant fly ash was studied using a modified extraction procedure, and the results showed that the highest concentrations occur in the leachate at pH 4.0 and decline with increasing pH.
TL;DR: In this paper, the instrumental neutron activation analysis technique (INAA) was used for homogeneity tests and certification analyses of coal fly ash reference materials ENO, ECH, and EOP prepared at the Institute of Radioecology and Nuclear Techniques (IRANT), Kosice, Czechoslovakia.
Abstract: The instrumental neutron activation analysis technique (INAA) was used for homogeneity tests and certification analyses of coal fly ash reference materials ENO, ECH, and EOP prepared at the Institute of Radioecology and Nuclear Techniques (IRANT), Kosice, Czechoslovakia Quantitative estimation of a degree of inhomogeneity was suggested The relative standard deviations due to inhomogeneity were found to be <1% for macroconstituents and <3% for minor and trace elements for sample weights about 25 mg The results of determination of the elements Al, As, Ba, Ca, Ce, Co, Cr, Cs, Dy, Eu, Fe, Ga, Hf, In, K, La, Mn, Na, Nd, Ni, Rb, Sb, Sc, Sm, Sr, Ta, Th, Ti, U, V, W, and Zn were compared with the IRANT certified or information values NBS SRM 1633a Trace Elements in Coal Fly Ash was also analyzed as a control sample and the results for the above elements were compared with the NBS certified, information or literature available values From these comparisons, inference was made on the quality of the IRANT specified values for the element contents
Patent•
27 Jul 1988
TL;DR: In this article, a method of treating subsurface layers of the earth for controlling movement of subsural water and building strength of the subsural layers characterized by injecting at a plurality of predetermined depths and at a multiplicity of predetermined spaced-apart locations a lime-fly ash slurry consisting essentially of water, particulate hydrated lime and particulate fly ash; the particulate lime and fly ash being present as particulate solids and a proportion of from twenty-five percent by weight of the water to as much as two hundred percent when employed along.
Abstract: Method of treating subsurface layers of the earth for controlling movement of subsurface water and building strength of the subsurface layers characterized by injecting at a plurality of predetermined depths and at a plurality of predetermined spaced-apart locations a lime-fly ash slurry consisting essentially of water, particulate hydrated lime and particulate fly ash; the particulate lime and fly ash being present as particulate solids and a proportion of from twenty-five percent by weight of the water to as much as two hundred percent by weight of the water when employed along. The particulate solids comprise lime and fly ash in proportions ranging from three parts lime to one part fly ash to one part lime to ten parts fly ash. The injection is carried out by pumping the slurry of one of the particulate solids and water through a jet slurry mixing apparatus for aspirating in the other dry particulate solid. Preferably the fly ash will be aspirated into a slurry of the lime in water. Injection occurs within less than ten minutes from admixture so as to obtain additional strength compared to conventional prior art processes. Minor amounts of additives may be employed to obtain desired properties. In particular embodiments there are disclosed the use of additional materials such as cement, attapulgite, sandy loam and bentonite. These additional materials may be employed in concentrations of twenty-five to two hundred percent by weight of the water and are in addition to the lime and fly ash in the slurry.
TL;DR: In this article, the leachability of heavy metals in municipal solid waste (MSW) incinerator residues was evaluated using equilibrium leach tests and the sequential chemical extraction procedure, and the bottom ash, boiler and economizer fly ashes were sampled from a two-stage combustion facility without pollution control devices.