Zeolite formation in the presence of cement hydrates and albite

Lothenbach, Barbara; Bernard, Ellina; Mäder, Urs

doi:10.1016/j.pce.2017.02.006

Cited by 69 publications

(58 citation statements)

References 55 publications

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“…This slightly higher value reported by Gómez-Zamorano et al 18 is likely due to the extended reaction time utilized in our experiments. Indeed, our data suggest that about 56 days were required to reach 46 measured the solubility of zeolite-X with a slightly different composition than that examined here, Si/Al = 1.25, and at 25°C. Applying our composition values to their stoichiometry, we are within 26% of their value.…”

Section: Calculation Of Solubility Products For N-a-s-(h) Phasesmentioning

confidence: 56%

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Relationship between aqueous chemistry and composition, structure, and solubility of sodium aluminosilicate hydrates

et al. 2019

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Inorganic polymer binders (IPBs) are synthesized by the activation of aluminosilicate precursors with an alkaline solution such as sodium hydroxide. This paper studies the relationship between the composition, structure, and solubility of sodium aluminosilicate hydrates (N–A–S–(H)), the primary binding phase in IPBs. It was found that changing the aqueous Si/Al ratio had little effect on N–A–S–(H) Si/Al ratio, but small changes in the aqueous Si/Na ratio led to substantial changes in N–A–S–(H) Si/Al ratio. Early N–A–S–(H) products were found to be X‐ray amorphous, but a rapid transition to the crystalline phase faujasite occurred after several weeks of aging. The transition of the solid amorphous phase to faujasite was accompanied by a rapid drop in aqueous Si(IV) and Al(III) concentrations. Solubility products were determined, temporally, for the N–A–S–(H) before and after the transition to faujasite and represent new contributions to the literature, particularly for the amorphous state. The results presented here provide fundamental insights that are needed for the development of kinetic and thermodynamic models that can establish phase balances and evolutions of IPBs across a range of precursor compositions and synthesis conditions.

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Section: Calculation Of Solubility Products For N-a-s-(h) Phasesmentioning

confidence: 56%

“…Lothenbach et al measured the solubility of zeolite‐X with a slightly different composition than that examined here, Si/Al = 1.25, and at 25°C. Applying our composition values to their stoichiometry, we are within 26% of their value.…”

Section: Resultsmentioning

confidence: 83%

Relationship between aqueous chemistry and composition, structure, and solubility of sodium aluminosilicate hydrates

et al. 2019

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“…Thermodynamic modelling was carried out using the Gibbs free energy minimization program GEMS v3.3 23,24 . The thermodynamic data for aqueous species, solids and gas phases include the PSI-GEMS thermodynamic database 25,26 and cement specific data base 27 including some zeolites 28,29 . To simulate the effect of the carbonation of the cement pastes, for the thermodynamic calculation, the cement pastes were titrated with the pure CO 2 .…”

Section: Methodsmentioning

confidence: 99%

Carbon Capture and Utilization by mineralization of cement pastes derived from recycled concrete

Skoček

Zając

Haha

2020

Sci Rep

128

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Reduction of co 2 emissions associated with cement production is challenging in view of the increasing cement demand and the fact that major part of the emissions originates from the main raw material used -limestone -which can be only to extremely low amount substituted. A carbon capture and Utilization (CCU) approach based on mineralization of fines derived from concrete appears to be a viable alternative to reduce these emissions. the co 2 sequestration and the reactivity of the obtained carbonated recycled fines is experimentally demonstrated for lab as well as industrial materials for different mineralization conditions. It is shown that all CO 2 originally released by limestone calcination during clinker production can be sequestered by the full carbonation of the fines within a short time. Upon full carbonation, gels with pozzolanic properties form in the fines irrespective of the conditions tested. The carbonated fines have specific CO 2 savings more than 30% higher than the simple clinker replacement by limestone.Global urbanization and economic development increase demand for new buildings and infrastructure and hence for concrete. Already now, concrete is the second most used substance by mass after water. Even though concrete has low specific CO 2 emissions below 150 kg CO2,eq /ton concrete 1 , its abundance makes it responsible for 5-8% of man-made CO 2 emissions 1-4 . Most of the concrete's emissions result from production of the main cement component, the clinker. Hence, focus of researchers as well as of cement producers has been on lowering the clinker content in cements and on improving the efficiency of clinker production. As summarized in 1 , both these approaches have already reached their potentials in mature economics. Almost all suitable Supplementary Cementitious Materials (SCMs) available are already used in cement and concrete production. For the clinker production, further energy efficiency improvements would have only a minor effect as the energy consumption approaches the lowest theoretical value and is often driven by additional objectives such as alternative fuels usage rate.Nevertheless, the cement industry needs to drastically reduce its emissions and at the same time satisfy the increasing cement demand of the global economy 5 . At the level of concrete structures and concrete applications, several approaches can bring considerable CO 2 savings. These include re-usable structures with extended service life or concretes with reduced cement contents 3,6 . At the level of cement production, extended use of calcined clays and limestone as SCM are the only approaches applicable at large enough scale. With the ongoing departure from coal-fired power plants and decreasing demand for pig iron in mature markets, the availability of blast furnace slags and fly ashes is expected to decrease. Calcined clays and limestone have the potential to replace these SCMs in the current market as well as provide sufficient volumes of SCMs in growing markets. However, clinker replacement by limestone o...

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“…Currently, a few zeolite phases are included in thermodynamic databases, e.g., llnl.dat 50 and sit.dat in PhreeqC, 26,27 ThermoChimie, 51 Thermoddem, 52 and GEMS, 53 which are integrated with solvers that compute stable phase equilibria based on the Law of Mass Action (LMA, e.g., PhreeqC 26,27 ) or Gibbs Energy Minimization (GEM, e.g., GEMS-Selektor 29 ). GEMS offers the advantage of automatically deriving a complete dataset of thermodynamic properties and extrapolating solubility constants at temperatures up to (and above) 100°C.…”

Section: Introductionmentioning

confidence: 99%

“…GEMS offers the advantage of automatically deriving a complete dataset of thermodynamic properties and extrapolating solubility constants at temperatures up to (and above) 100°C. 53 Therefore, by using the GEMS approach and integrating available calorimetry data, [54][55][56][57][58][59][60][61] we compiled a unified, internally-consistent thermodynamic database to predict zeolite stability in neutral and alkaline solutions at low temperatures. The database when integrated with the GEMS solver is shown to correctly assess the propensity for zeolite formation, and predicted stability fields for a multiplicity of zeolite compositions viz-a-viz experimental observations.…”

Section: Introductionmentioning

confidence: 99%

zeo19: A thermodynamic database for assessing zeolite stability during the corrosion of nuclear waste immobilization glasses

et al. 2020

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Stable, durable immobilization of radioactive wastes requires robust understanding of the sub-surface geochemical processes that occur in repository environments. For example, the accelerated dissolution (corrosion) of nuclear waste immobilization glasses (i.e., the so-called "Stage III" corrosion) following the precipitation of zeolitic phases is a significant issue that could result in radionuclide release. However, current uncertainties in establishing the tendency for the persistence of zeolites results in difficulties in estimating the chemical environments and state variables that favor zeolite precipitation. To assess the tendency for Stage III corrosion, we compiled a unified, internally-consistent thermodynamic database to estimate zeolite stability under conditions relevant to nuclear waste repositories (namely, p = 1 bar and T < 95°C), i.e.

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Zeolite formation in the presence of cement hydrates and albite

Cited by 69 publications

References 55 publications

Relationship between aqueous chemistry and composition, structure, and solubility of sodium aluminosilicate hydrates

Relationship between aqueous chemistry and composition, structure, and solubility of sodium aluminosilicate hydrates

Carbon Capture and Utilization by mineralization of cement pastes derived from recycled concrete

zeo19: A thermodynamic database for assessing zeolite stability during the corrosion of nuclear waste immobilization glasses

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