Enhanced thermodynamic analysis coupled with temperature-dependent microstructures of cement hydrates

Nakarai, Kenichiro; Ishida, Tetsuya; Kishi, Toshiharu; Maekawa, Koichi

doi:10.1016/j.cemconres.2006.10.006

Cited by 20 publications

(14 citation statements)

References 7 publications

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“…The second assumption is that the reaction rate would gradually reduce due to the calcium carbonate and silica gel generated by the reaction accumulating on the surface of the C-S-H gel, so the following model was proposed. Measured values by Kroone and Crock (1961) Large discrepancy between the measured values and the theoretical values (Maekawa et al 1999, Nakarai et al 2007. In this research the mass of C-S-H gel is obtained by subtracting the mass of calcium hydroxide from the total mass of hydration products W hyd .…”

Section: Equation For Carbonation Reaction Rate At Normal Temperaturesmentioning

confidence: 99%

“…By inputting the calculated mass and volume of each substance after the reaction into a micro-pore structure formation model (Maekawa et al 1999;Maekawa et al 2003;Nakarai et al 2007), the porosity and pore-distribution at an arbitrary stage can be automatically obtained. When we simulate the early-age development process, the micro-pore structure formation model needs the mass and volume of calcium hydroxide and C-S-H gel generated by hydration so that it calculate the micro-pore structure formation at an arbitrary stage of early age development.…”

Section: Change In the Specific Surface Area Of C-s-h Gel Due To Carbmentioning

confidence: 99%

“…In the micro-pore structure development model (Maekawa et al 1999, Nakarai et al 2007, the pores in the cement paste are classified into three types: interlayer, gel pores, and capillary pores. Capillary pores are free spaces for the precipitation of hydrates, whereas gel pores are located inside the C-S-H gel grain and in the inter-particle space between the hydrate products.…”

Section: Outline Of Existing Carbonation Model and Its Verificationmentioning

confidence: 99%

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Modeling of Carbonation based on Thermo-Hygro Physics with Strong Coupling of Mass Transport and Equilibrium in Micro-pore Structure of Concrete

Ishida

2008

ACT

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A carbonation model based on thermo-hygro physics is presented in this paper. Reaction of C-S-H gel was newly added to the existing model as well as calcium hydroxide reaction, and a micro-pore structure model for carbonated concrete was improved by considering volume change and surface-area increase of hydrated products. The proposed model coupled with moisture equilibrium/transport gives reasonable predictions for carbonation progresses under low and high CO 2 concentrations in a unified manner. In addition, temperature dependent parameters were installed in the system. Although detailed mechanisms should be further investigated, the proposed methodology is able to simulate carbonation phenomena under various temperature conditions.

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Section: Equation For Carbonation Reaction Rate At Normal Temperaturesmentioning

confidence: 99%

Section: Change In the Specific Surface Area Of C-s-h Gel Due To Carbmentioning

confidence: 99%

Section: Outline Of Existing Carbonation Model and Its Verificationmentioning

confidence: 99%

See 1 more Smart Citation

Modeling of Carbonation based on Thermo-Hygro Physics with Strong Coupling of Mass Transport and Equilibrium in Micro-pore Structure of Concrete

Ishida

2008

ACT

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“…The expression for saturation (S) is changed with hysteretic behavior of isotherm. Each model is well explained and documented in following references [15][16][17][18][19].…”

Section: Mulɵ Component Hydraɵon Heat Modelmentioning

confidence: 99%

“…For the chloride effect on drying shrinkage, tests for water evaporation and free drying without restraint are performed. Considering the chloride effect on experimental data on drying shrinkage, an analysis technique for the restrained drying shrinkage in concrete with chloride contents is proposed through utilizing the previously developed models [15][16][17][18][19], so called, multi-component hydration heat model (MCHHM), micro-pore structure formation model (MPSFM), and moisture transport model (MTM). Integrated FE analysis using the proposed models is carried out and the reduced cracking time caused by restrained drying shrinkage is evaluated in the concrete with different chloride contents.…”

Section: Introductionmentioning

confidence: 99%

Analysis technique for restrained shrinkage of concrete containing chlorides

2010

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Cracks in concrete containing chlorides easily occur due to restraint conditions and they can be the main reasons of durability and safety issues. In this paper, analysis technique which can handle mixed chloride and its effect on restrained drying shrinkage is proposed. For the evaluation of stress development and cracking time due to restrained drying shrinkage, free and restrained drying shrinkage test are carried out for concrete specimens containing different sodium chloride (NaCl) content. The results show that mixed chloride content increases restraint stress but does not increase strength. Considering the effect of chloride on shrinkage based on the test results, effective restraint stress development and cracking of concrete specimens containing different level of chloride are evaluated through utilizing previously developed models for behaviors in early-age concrete like hydration and moisture transport. The results from this proposed technique are verified by comparison with test results.

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Modeling of cement hydration in high performance concrete structures with hybrid finite elements

Freitas

Cuong

Faria

2015

Numerical Meth Engineering

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Summary A hybrid finite element formulation is used to model the hygro‐thermo‐chemical process of cement hydration in high performance concrete. The temperature and the relative humidity fields are directly approximated in the domain of the element using naturally hierarchical bases independent of the mapping used to define its geometry. This added flexibility in modeling implies the independent approximation of the heat and moisture flux fields on the boundary of the element, the typical feature of hybrid finite element formulations. The formulation can be implemented using coarse and, eventually, unstructured meshes, which may contain elements with high aspect ratios, an option that can be advantageously used in the simulation of the casting of concrete structural elements. The resulting solving system is sparse and well suited to adaptive refinement and parallelization. It is solved coupling a trapezoidal time integration rule with an adaptation of the Newton–Raphson method designed to preserve symmetry. The relative performance of the formulation is assessed using a set of testing problems supported by experimental data and results obtained with conventional (conform) finite elements. Copyright © 2015 John Wiley & Sons, Ltd.

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Enhanced thermodynamic analysis coupled with temperature-dependent microstructures of cement hydrates

Cited by 20 publications

References 7 publications

Modeling of Carbonation based on Thermo-Hygro Physics with Strong Coupling of Mass Transport and Equilibrium in Micro-pore Structure of Concrete

Modeling of Carbonation based on Thermo-Hygro Physics with Strong Coupling of Mass Transport and Equilibrium in Micro-pore Structure of Concrete

Analysis technique for restrained shrinkage of concrete containing chlorides

Modeling of cement hydration in high performance concrete structures with hybrid finite elements

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