Monitoring of Fluctuations in the Physical and Chemical Properties of a High-Calcium Fly Ash

Schlorholtz, Scott; Bergeson, Ken; Demirel, T

doi:10.1557/proc-113-107

Cited by 13 publications

(5 citation statements)

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“…Several excellent reviews of fly ash chemical and mineralogical compositions and properties are given in Helmuth (1987, McCarthy (1988), Hemmings and Berry (1988), , Dudas and Warren (1988), Stevenson, et al (1988), Berry, et al (1988), Bellotto, et al (1990, Schlorholtz, et al (1988), and Kilgour and Diamond (1988), to which the reader is referred for detailed discussions of formation processes and resulting elemental and compound partitioning in fly ashes. A brief overview is given in the following discussions.…”

Section: Fly Ashesmentioning

confidence: 99%

“…In addition to the pozzolanic glass hydration mentioned for (Poellmann, 1990, Poellmann, et al, 1989. Strätlingite has been suggested to contribute to strength development in self-hardening high calcium fly ashes (Schlorholtz, et al, 1988), and forms from hydration of calcium aluminosilicate glasses.…”

Section: Hydration Of Intermediate and High Calcium Fly Ashesmentioning

confidence: 99%

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Residues From Coal Conversion and Utilization: Advanced Mineralogical Characterization and Disposed Byproduct Diagenesis

McCarthy¹,

Grier²

2001

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Prior to the initiation of this study, understanding of the long-term behavior of environmentallyexposed Coal Combustion By-Products (CCBs) was lacking in (among others) two primary areas addressed in this work. First, no method had been successfully applied to achieve full quantitative analysis of the partitioning of chemical constituents into reactive or passive crystalline or noncrystalline compounds. Rather, only semi-quantitative methods were available, with large associated errors. Second, our understanding of the long-term behavior of various CCBs in contact with the natural environment was based on a relatively limited set of study materials. This study addressed these areas with two objectives, producing 1) a set of protocols for fully quantitative phase analysis using the Rietveld Quantitative X-ray Diffraction (RQXRD) method and 2) greater understanding of the hydrologic and geochemical nature of the long-term behavior of disposed and utilized CCBs. The RQXRD technique was initially tested using 1) mixtures of National Institute of Standards and Technology (NIST) crystalline standards, and 2) mixtures of synthetic reagents simulating various CCBs, to determine accuracy and precision of the method, and to determine the most favorable protocols to follow in order to efficiently quantify multi-phase mixtures. Four sets of borehole samples of disposed or utilized CCBs were retrieved and analyzed by RQXRD according to the protocols developed under the first objective. The first set of samples, from a Class F ash settling pond in Kentucky disposed for up to 20 years, showed little mineralogical alteration, as expected. The second set of samples, from an enbankment in Indiana containing a mixture of chain-grate (stoker) furnace ash and fluidized bed combustion (FBC) residues, showed formation of the mineral thaumasite, as observed in previously studied exposed FBC materials. Two high-calcium CCBs studied, including a dryprocess flue gas desulfurization (FGD) by-product disposed in the Midwest, and a mixture of Class C fly ash and wet process FGD by-product codisposed in North Dakota, appeared relatively unchanged mineralogically over the up to 5 and 17 years of emplacement, respectively. Each of these two materials contained mineralogies consistent with short-term hydration products of their respective starting (dry) materials. The hydration product ettringite persisted throughout the duration of emplacement at each site, and the diagenetic ash alteration product thaumasite did not form at either site. Explanations for the absence of thaumasite in these two sites include a lack of significant carbonate, sulfate, and alkalinity sources in the case of the North Dakota site, and a lack of sulfate, alkalinity, and sufficient moisture in the Midwest site. Potential for future thaumasite formation in these materials may exist if placed in contact with cold, wet materials containing the missing components listed above. In the presence of the sulfite scrubber mineral hannebachite, the ettringites formed had ...

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Section: Fly Ashesmentioning

confidence: 99%

Section: Hydration Of Intermediate and High Calcium Fly Ashesmentioning

confidence: 99%

Residues From Coal Conversion and Utilization: Advanced Mineralogical Characterization and Disposed Byproduct Diagenesis

McCarthy¹,

Grier²

2001

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“…However, the activity of fly ash cannot be estimated only based on the chemical composition from XRF analysis. Prior art demonstrated that fly ash had considerably different performance in concrete even though containing similar bulk chemical composition [10][11][12][13]. With EDS, according to the content of Al, Si and Ca, fly ash can be divided into several groups, possessing certain hydraulic activity [12,[14][15].…”

Section: Introductionmentioning

confidence: 99%

Assessment of the quantitative accuracy of Rietveld/XRD analysis of crystalline and amorphous phases in fly ash

et al. 2017

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“…P. Chindaprasert et al[93,94] reported that the incorporation of FA and its fineness significantly affected on the total porosity and pore size of blended cement systems having FA.However, the civil engineering applications of blended FA-cementing materials continue having a practical challenge due to a wide variability and heterogeneity of FA. When many researchers[44,95] studied the wide variation of FA, their results showed that the when mixing cement with FA having different chemical compositions led to changes in compressive strengths, pore-size distribution, and its ability to resist chloride concentration even though such FA came from the same power plant. This is due to the combustion condition, surrounding environmental conduction during firing, and composition of the raw feed[96,97] Wang et al (2019…”

mentioning

confidence: 99%

“…Therefore, both have similar compressive strengths at 90 days. According to Schlorholtz et al[95], although fly ash for different batches were obtained from the same power plant, the performance of final product of fly ash-cement composite can be remarkably different.Because fly ash is a pozzolan, its reaction to cement delivers enhanced concrete quality through the pozzolanic reactions. Pozzolanic materials react with Ca(OH)2 phase and H2O to form compounds with cementitious properties.…”

mentioning

confidence: 99%

Effect of fly ash in Southeast Asia on the properties of concrete

Win¹

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A wide use of fly ash (FA) as a supplementary cementitious material (SCM) can result in an enhancement in its durability performance in our civil engineering applications. Although FA is either agricultural or industrial by‑product and is abundant for use in cement and concrete works for many decades now, the utilization of FA still has a practical challenge. The challenge is due to variability and their heterogeneity. In Southeast Asia, fly ash is used in concrete production replacing cement as a pozzolanic material. However, there are few standard guidelines for using fly ash across the region. This study evaluates the durability of cementitious materials after the including of five types of fly ash in different mix proportions from three countries, Myanmar, Thailand, and Indonesia. For the mathematical model, each type is used to replace ordinary Portland cement in 15 % with a water-to-binder ratio of 0.54. Moreover, this work is to perform both experimental and numerical studies to have a better insight for controlling the different FA, reflecting its durability. FA from five different sources were assessed to investigate the impacts on its chemical composition and physical properties. The blended FA-cement systems were also prepared and evaluated on its flow, compressive strength of mortar, hardened porosity, ability to resist chloride penetration, apparent chloride diffusivity coefficients (Da), and carbonation resistance after 7, 28, and 91 days, and degree of reaction. Because the chemical composition of each country’s fly ash is slightly different, their chemical reaction with cement is marginally different. Thus, the durability performances of the mortar are better for finer fly ash types at an early age. The service life model using Life365 was performed to predict the service life of blended FA-cement system. The experimental results were statistically analyzed using analysis of variance (ANOVA) and sensitivity analysis with linear regression. The analyses indicate that chemo-physical mechanisms of multi-scale structures are the main factors, and both degree of reaction of blended FA-cement systems and its hardened porosity are among the most positive factors influencing its durability.

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Monitoring of Fluctuations in the Physical and Chemical Properties of a High-Calcium Fly Ash

Cited by 13 publications

References 0 publications

Residues From Coal Conversion and Utilization: Advanced Mineralogical Characterization and Disposed Byproduct Diagenesis

Residues From Coal Conversion and Utilization: Advanced Mineralogical Characterization and Disposed Byproduct Diagenesis

Assessment of the quantitative accuracy of Rietveld/XRD analysis of crystalline and amorphous phases in fly ash

Effect of fly ash in Southeast Asia on the properties of concrete

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