Calculation of the Compounds in Portland Cement

Bogue, R. H.

doi:10.1021/ac50068a006

Cited by 226 publications

(111 citation statements)

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“…Several methods can be used to determine the phase composition using the stoichiometry of those compounds and the respective amounts of the former oxides. The approach adopted in this study is a widely used method developped by Bogue [22]. It consists in a linear system of equations based on a quantitative oxide composition (see Table 1) under certain assumptions:…”

Section: Methodsmentioning

confidence: 99%

Uncertainty propagation of a multiscale poromechanics-hydration model for poroelastic properties of cement paste at early-age

Venkovic¹,

Sorelli²,

Sudret³

et al. 2013

Probabilistic Engineering Mechanics

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The durability of concrete materials with regard to early-age volume changes and cracking phenomena depends on the evolution of the poroelastic properties of cement paste. The ability of engineers to control the uncertainty of the percolation threshold and the evolution of the elastic modulus, the Biot-Willis parameter and the skeleton Biot modulus is key for minimizing the vulnerability of concrete structures at early-age. This work presents original results on the uncertainty propagation and the sensitivity analysis of a multiscale poromechanics-hydration model applied to cement pastes of water-to-cement ratio of 0.40, 0.50 and 0.60. Notably, the proposed approach provides poroelastic properties required to model the behavior of partially saturated aging cement pastes (e.g. autogenous shrinkage) and it predicts the percolation threshold and undrained elastic modulus in good agreement with experimental data. The development of a stochastic metamodel using polynomial chaos expansions allows to propagate the uncertainties of kinetic parameters of hydration, cement phase composition, elastic moduli and morphological parameters of the microstructure. The presented results show that the propagation does not magnify the uncertainty of the single poroelastic properties although, their correlation may amplify the variability of the estimates obtained from poroelastic state equations. In order to reduce the uncertainty of the percolation threshold and that of the poroelastic properties at early-age, engineers need to assess more accurately the apparent activation energy of calcium aluminate and, later on, of the elastic modulus of low density calcium-silicate-hydrate.

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Section: Methodsmentioning

confidence: 99%

Uncertainty propagation of a multiscale poromechanics-hydration model for poroelastic properties of cement paste at early-age

Venkovic¹,

Sorelli²,

Sudret³

et al. 2013

Probabilistic Engineering Mechanics

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“…The first step of the model is to calculate a mineralogical composition (i.e., clinker minerals) of the cement from an analysis of its initial oxide composition. This calculation was performed using the approach suggested by Bogue (1929). In the second step of the model, a set of hydration reactions is used to simulate the reaction of these clinker minerals with watet The suite of solids resulting from these calculated reactions represents the phase assemblage for the hydrated cement.…”

Section: -mentioning

confidence: 99%

Effects on radionuclide concentrations by cement/ground-water interactions in support of performance assessment of low-level radioactive waste disposal facilities

Krupka¹,

Serne²

1998

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C o p k r o f h b r t r y~m d r t n d v d r u n d h 8~m m r h t h . N R C~~r AbstractThe U.S. Nuclear Regulatory Commission (NRC) is developing a technical position document that provides guidance regarding the performance assessment of low-level radioactive waste (LLW) disposal facilities. This guidance includes considerations associated with the chemical environment of the vault disposal system and the effects this system may have on the release and mobility of radionuclides. Because the disposal system will contain cementitious materials as structural, waste form, andor bacld'ill materials, the geochemical properties of pore waters buffered by reactions with cement will be very different from those waters associated with the local soil and geology. This environment therefore needs to be considered within the source term calculations if credit is taken for solubility limits andor distribution coefficients for -dissolved radionuclide concentrqtions within disposal units. Geochemical modeling may be used to assess potential chemical conditions in concrete vault disposal units and associated effects on aqueous speciation, solubilities, and sorption of radionuclides that are released from the waste form.In support of NRC7s development of this technical position, two literature reviews were done on information related to the chemical environments associated with the interaction of water with cementitious materials. One review was conducted on methods and associated solid-phase assemblages used to model the composition of pore water resulting from reaction with cementitious materials used in a disposal vault. This literature review also included related information on experimental studies of cemendwater systems, natural analogue studies of cement and concrete, and radionuclide solubilities experimentally determined in cement pore fluids.Based on the results of .this review, geochemical modeling was used to demonstrate the calculation of conservative maximum concentrations for dissolved americium, neptunium, nickel, plutonium, radium, strontium, thorium, and uranium with respect to key geochemical input parameters for two ground-water environments associated with the disposal system. These environments include 1) a cement buffered system, wherein the leachate pH is controlled at values above 10 by the effective buffering capacity of the concrete; and 2) a ground-water buffered system, wherein the leachate pH and related solution parameters are dominated by the local ground-water system.Another literature review was completed on the available data for the sorption potential of selected LLW radionuclides onto "fresh" cement/concretewhere the expected pH of the cement pore waters will equal or exceed 10. The review included data for the radionuclides americium, inorganic carbon, chlorine, iodine, lanthanide elements, niobium, nickel, neptunium, plutonium, radium, strontium, technetium, thorium, and uranium. Based on information gleaned from the literature, a database was developed of preferred minimum distribution coeff...

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“…La composición (expresada en óxidos) del OPC y del SRC se determinó mediante fluorescencia de rayos X con un equipo Philips X-CEM, calculán-dose su composición por fases de acuerdo con las ecuaciones de Bogue (13). El porcentaje de caliza en el LSC se calculó mediante la pérdida por calcinación.…”

Section: Methodsunclassified

“…The oxide composition of the OPC and SRC was determined by means of X-ray fluorescence, Philips instrument type X-CEM; and their phase composition was calculated according to Bogue equations (13). The percentage of calcite in LSC was estimated on the basis of the loss of ignition.…”

Section: Methodsmentioning

confidence: 99%

Interacción entre cementos de diferente composición y aditivos superplastificantes

Ghorab

Kenawi

All³

2012

Mater. construcc.

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RESUMENSe ha estudiado el efecto fluidificante (hasta 90 minutos) ejercido por la incorporación de entre 0-1% de aditivos policondensados y policarboxilatos en pastas de cemento Portland, puzolánico, resistente a sulfatos y con adición de caliza.Con la incorporación de los aditivos policondensados, se produjo un incremento de la fluidez de los cementos Portland y puzolánico a mayores dosificaciones que las necesarias en los cementos resistente a sulfatos y con adición de caliza. Éste último presentó la mejor retención de la fluidez. Las fases aluminatos y sulfatos juegan un importante papel en la fluidez inducida.Todos los cementos incrementaron su fluidez con la incorporación de aditivos policarboxilatos a dosificaciones menores del 0,3%. El policarboxilato que no presenta en los espectros de RMN, resonancia asignada al protón de los grupos metil metileno, presenta buena retención de la fluidez. Esto es debido a la baja flexibilidad de la estructura y predominancia del efecto estérico. Este aditivo presenta también, mayor relación de grupos eter frente a grupos ester en los espectros IR, asi como una baja polidispersidad observada en la elución de especies de bajo peso molecular a través de HPLC.Palabras clave: cemento, superplastificantes, compatibilidad, fluidez, "minislump". SUMMARYThe slump behavior of ordinary Portland-, pozzolanic (red brick powder)-, sulfate resistant-, and limestone cement pastes caused by ≤1% additions of polycondensates and polycarboxylates superplasticizers are monitored for up to 90 minutes.With the plolycondensates, Portland-and pozzolanic cements gain fluidity at higher dosages than sulfate resistant and limestone cements. Limestone cement shows the best slump retention. The aluminate and sulfate phases play a major role in the fluidity.With the polycarboxylates, all cements gain fluidity with dosages of ≤0.3%. A polycarboxylate with no resonance of methyl methylene proton in the main chain identified in the NMR spectra creates good slump retention. This is explained by a low mobility of the structure and the predominance of the steric effect. The polycarboxylate shows also strong ether bands relative to the ester groups in the IR spectra and a low polydispersity observed in the elution of few low molecular weight species in the HPLC chromatogram.Keywords: cement, superplasticizers, compatibility, fluidity, minislump. Persona de contacto/Corresponding author: hanaa.ghorab@gmail.com INTRODUCCIÓNLos aditivos superplastificantes, también conocidos como reductores de agua de alto rango, que surgieron en los años sesenta del siglo pasado (1), son aditivos orgánicos cuya incorporación a los sistemas cementicios mejoran las propiedades mecánicas, permitiendo menores relaciones agua/cemento e incrementando su trabajabilidad. A lo largo del siglo XX-XXI se produjo la mejora progresiva de estos aditivos, que han llegado a ser componentes esenciales en la fabricación de hormigón de altas prestaciones. Los superplastificantes más empleados se basan en grupos sulfanados (de poli-ß-naftaleno y ...

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Calculation of the Compounds in Portland Cement

Cited by 226 publications

References 0 publications

Uncertainty propagation of a multiscale poromechanics-hydration model for poroelastic properties of cement paste at early-age

Uncertainty propagation of a multiscale poromechanics-hydration model for poroelastic properties of cement paste at early-age

Effects on radionuclide concentrations by cement/ground-water interactions in support of performance assessment of low-level radioactive waste disposal facilities

Interacción entre cementos de diferente composición y aditivos superplastificantes

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