Research review of cement clinker chemistry

Ludwig, Horst‐Michael; Zhang, Wensheng

doi:10.1016/j.cemconres.2015.05.018

Cited by 225 publications

(110 citation statements)

References 91 publications

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“…Portland cement, the most utilized artificial materials in the world, has incurred much disapproval due to its considerable environmental footprint . Property modification of cement clinker by chemical doping is promising for reducing the carbon dioxide emissions as well as energy consumption of cement manufacturing . For many years, multifarious ionic doping schemes have been experimented to reduce the sintering temperature, control the polymorphic transformation of clinker phases, improve the hydration reactivity of the low‐activity phase, and modify the exothermic process of clinker hydration .…”

Section: Introductionmentioning

confidence: 99%

“…1 Property modification of cement clinker by chemical doping is promising for reducing the carbon dioxide emissions as well as energy consumption of cement manufacturing. 2 For many years, multifarious ionic doping schemes have been experimented to reduce the sintering temperature, 3 control the polymorphic transformation of clinker phases, 4 improve the hydration reactivity of the low-activity phase, 5 and modify the exothermic process of clinker hydration. 6 However, the realistic doping effect for most of these attempts is complicated and uncontrollable as the fact that numerous experimental results related to the doping effect on cement clinker are conflicting 7-10 and the associated mechanism interpretations are controversial.…”

Section: Introductionmentioning

confidence: 99%

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Fundamental principles that govern the copper doping behavior in complex clinker system

Tao

Zhang

et al. 2018

J Am Ceram Soc

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Understanding the doping behavior of impurity ions in clinker phases is crucial for controlling the doping effect on clinker compounds, which, however, has not yet been fully demonstrated due to the composition complexity. Herein, we employ the state‐of‐the‐art ab initio calculation to uncover the substitution mechanism of Cu ions in 4 dominant clinker crystals. The defect formation energies indicate Cu ions energetically prefer to substitute Fe ions in ferrite, which is in accord with the experiments. The bond order difference is innovatively postulated to interpret the energy barriers of Cu substitution in comparison with the ionic radius criterion. The high potential barriers of Cu substituting Ca, Si, and Al ions are ascribed to their bond order mismatch, while the tendency of Cu replacing Fe is due to their bond order similarity. Namely, the Cu doping in clinker phases follows the “bond order conformity” principle. In‐depth electronic structure analysis reveals that the bond order is more effective than the ionic radius to estimate potential barriers of Cu substitution in complex clinker system mainly because the latter underestimates the influence of electronic structure differences while the bond order directly measures the bonding structure related to interatomic charge transfer.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fundamental principles that govern the copper doping behavior in complex clinker system

Tao

Zhang

et al. 2018

J Am Ceram Soc

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“…It consists of the dissolution of Ca 3 SiO 5 , the supersaturation of the medium with the different ionic species, and then, the precipitation of a calcium silicate hydrate, C-S-H gel in cement nomenclature, and the crystallization of portlandite, c-Ca(OH) 2 , which can be followed by powder diffraction [4]. This set of actions can be schematically represented by reaction (1), but the different processes (may) have different kinetics and be locally inhomogeneous. Therefore, reaction (1) is a simplification for alite hydration.…”

Section: Cementsmentioning

confidence: 99%

“…Portland cement (PC) is considered the most manufactured product in the world, as it is the main component of the construction industry [1]. PC is composed of the Portland clinker, the setting regulator (a calcium sulfate source), and in many cases additions and admixtures [2].…”

Section: Cementsmentioning

confidence: 99%

Synchrotron Radiation Pair Distribution Function Analysis of Gels in Cements

et al. 2017

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Abstract:The analysis of atomic ordering in a nanocrystalline phase with small particle sizes, below ≈5 nm, is intrinsically complicated because of the lack of long-range order. Furthermore, the presence of additional crystalline phase(s) may exacerbate the problem, as is the case in cement pastes. Here, we use the synchrotron pair distribution function (PDF) chiefly to characterize the local atomic order of the nanocrystalline phases, gels, in cement pastes. We have used a multi r-range analysis approach, where the~4-7 nm r-range allows determining the crystalline phase contents; the~1-2.5 nm r-range is used to characterize the atomic ordering in the nanocrystalline component; and the~0.2-1.0 nm r-range gives insights about additional amorphous components. Specifically, we have prepared four alite pastes with variable water contents, and the analyses showed that a defective tobermorite, Ca 11 Si 9 O 28 (OH) 2 ·8.5H 2 O, gave the best fit. Furthermore, the PDF analyses suggest that the calcium silicate hydrate gel is composed of this tobermorite and amorphous calcium hydroxide. Finally, this approach has been used to study alternative cements. The hydration of monocalcium aluminate and ye'elimite pastes yield aluminum hydroxide gels. PDF analyses show that these gels are constituted of nanocrystalline gibbsite, and the particle size can be as small as 2.5 nm.

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“…Damtoft et al estimated a total of ~0.87 tonnes of carbon dioxide for every tonne of ordinary Portland cement (OPC) produced . Efforts to reduce CO 2 emissions include improving the energy efficiency of kilns, carbon capture and storage, clinker substitution, and alternative binder development . The aim of this work was to study the early age properties of a promising alternative binder.…”

Section: Introductionmentioning

confidence: 99%

Sodium silicate activated slag‐fly ash binders: Part III—Composition of soft gel and calorimetry

2018

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Sodium silicate activated, slag‐fly ash binders are potential alternative binders to Portland cement. In this study, the early age properties of slag‐fly ash binders namely, set time, and heats of reaction were investigated. Set time was investigated using a combination of two methods namely, the ASTM C403 penetration testing, and s‐wave ultrasonic wave reflectometry (SUWR). The discrepancy in set time identified by these two methods suggested the presence of a soft gel which eventually hardened with time. The composition of this soft gel was analyzed by suspending the chemical reaction of the binder after the soft gel formed, but before it hardened. In order to analyze the composition of the soft gel, selective chemical extractions were performed on the binder. 29Si Magic Angle Spinning‐Nuclear Magnetic Resonance (MAS‐NMR), and FTIR spectroscopy were performed on binders and extraction residues. The soft gel contained a modified calcium silicate hydrate gel (C–N–S–H where N=Na), with a short mean chain length and no observable Al incorporation. Orthosilicate units were also found to be present in relatively high proportions when compared to hardened binders at later ages.

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Research review of cement clinker chemistry

Cited by 225 publications

References 91 publications

Fundamental principles that govern the copper doping behavior in complex clinker system

Fundamental principles that govern the copper doping behavior in complex clinker system

Synchrotron Radiation Pair Distribution Function Analysis of Gels in Cements

Sodium silicate activated slag‐fly ash binders: Part III—Composition of soft gel and calorimetry

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