Preferred orientation of calcium aluminosilicate hydrate compacts: Implications for creep and indentation

Li, Jiaqi; Zhang, Wenxin; Monteiro, Paulo J.M.

doi:10.1016/j.cemconres.2021.106371

Cited by 49 publications

(9 citation statements)

References 78 publications

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“…The first one is that the secondary reaction products of AAS are mainly amorphous 46 while portlandite and ettringite, present in OPC concrete as crystalline phases, have a negligible contribution to creep. 47 Hence, with higher amounts of amorphous phases, AAS would creep more. The second explanation could be due to the microstructure of the C-A-S-H gel.…”

Section: Experimental Creep Results Of Aas Concretementioning

confidence: 99%

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Experimental study on basic and drying creep for an alkali‐activated slag concrete and comparison with existing creep models

Caron

Patel

Dehn

2023

Structural Concrete

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Slag is a by‐product of the steel industry that can be activated using alkali solutions to form concrete. This study presents new experimental results of basic and drying creep behavior of alkali‐activated slag (AAS) concrete. Different parameters affecting creep such as loading age, sample size and creep stress‐strength ratio were varied for experimental studies. The results show that the basic creep of AAS concrete is higher than that of ordinary Portland cement (OPC) concrete. The drying creep of AAS is lower than for OPC and this could be explained by a higher internal drying during the activation of slag. The experimental results were used to check the applicability of two existing engineering models, the fib MC 2010 and the B4s model, for AAS concrete. It was found that both models could be extended to predict the basic creep of AAS concrete. For drying creep, the B4s could better capture the creep behavior. For the fib MC 2010, a new formulation for drying creep would be required.

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Section: Experimental Creep Results Of Aas Concretementioning

confidence: 99%

“…At least two mechanisms could explain the higher creep of AAS. The first one is that the secondary reaction products of AAS are mainly amorphous 46 while portlandite and ettringite, present in OPC concrete as crystalline phases, have a negligible contribution to creep 47 . Hence, with higher amounts of amorphous phases, AAS would creep more.…”

Section: Resultsmentioning

confidence: 99%

Experimental study on basic and drying creep for an alkali‐activated slag concrete and comparison with existing creep models

Caron

Patel

Dehn

2023

Structural Concrete

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“…Although the materials listed above may not all lend themselves to the generation of realistic microstructures through the approach used here (i.e., MD simulation of spontaneous or compaction-driven self-assembly), evidence suggests that this approach holds promise, at least in certain cases. For example, experiments suggest that artificial cement created by compacting C–S–H nanoparticles has properties analogous to those of conventional cement created by growing C–S–H nanoparticles in situ . Similarly, coarse-grained MD simulations have contributed significant theoretical understanding of self-organization in liquid crystals and colloidal assemblages, , and all-atom MD simulations of this self-organization phenomenon represent a logical next step for properties or processes that are sensitive to atomistic-level details, such as the role of water in ionic liquids or in the oriented aggregation of mineral nanoparticles. , As in all MD simulation efforts, a key requirement is the existence of accurate interatomic potential models, a requirement that is fulfilled by the ClayFF model of hydrated phyllosilicate minerals used in this study.…”

Section: Discussionmentioning

confidence: 99%

Nanoscale Prediction of the Thermal, Mechanical, and Transport Properties of Hydrated Clay on 10⁶- and 10¹⁵-Fold Larger Length and Time Scales

Zheng,

Bourg

2023

ACS Nano

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Coupled thermal, hydraulic, mechanical, and chemical (THMC) processes, such as desiccation-driven cracking or chemically driven fluid flow, significantly impact the performance of composite materials formed by fluid-mediated nanoparticle assembly, including energy storage materials, ordinary Portland cement, bioinorganic nanocomposites, liquid crystals, and engineered clay barriers used in the isolation of hazardous wastes. These couplings are particularly important in the isolation of high-level radioactive waste (HLRW), where heat generated by radioactive decay can drive the temperature up to at least 373 K in the engineered barrier. Here, we use large-scale all-atom molecular dynamics simulations of hydrated smectite clay nanoparticle assemblages to predict the fundamental THMC properties of hydrated compacted clay over a wide range of temperatures (up to 373 K) and dry densities relevant to HLRW management. Equilibrium simulations of clay–water mixtures at different hydration levels are analyzed to quantify material properties, including thermal conductivity, heat capacity, thermal expansion, suction, water and ion self-diffusivity, and hydraulic conductivity. Predictions are validated against experimental results for the properties of compacted bentonite clay. Our results demonstrate the feasibility of using atomistic-level simulations of assemblages of clay nanoparticles on scales of tens of nanometers and nanoseconds to infer the properties of compacted bentonite on scales of centimeters and days, a direct upscaling over 6 orders of magnitude in space and 15 orders of magnitude in time.

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“…Dense C-S-H monoliths (pellets) were then demolded from the die and used for subsequent mechanical investigations. The sampling method follows previous work. , From − previous research, it is found that the loading condition and water content will have an influence on the preferred orientation of C-S-H pellets. In this study, the C-S-H powders were stored in 8 and 100% RH conditions.…”

Section: Methodsmentioning

confidence: 99%

Interfacial Degradation of Calcium Silicate Hydrate and Epoxy under a Hygrothermal Environment: An Experimental and Molecular Model Study

Luo

Zhang

et al. 2023

J. Phys. Chem. C

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The adhesion at the concrete/epoxy interface is crucial to the reinforcement of carbon fiber-reinforced polymer (CFRP) sheets. The multiscale mechanism of adhesion, particularly under a hygrothermal environment, yet remains largely unclear. This paper combines molecular dynamics (MD) and synthesis experiments of a novel single-phase calcium silicate hydrate (C-S-H) and epoxy composite to investigate the combined effects of aggressive chemicals and temperature on the bonding properties. MD models were constructed under various conditions on C-S-H/epoxy composites, whose equilibrium configuration, dynamic property, bond connection, interfacial interaction energy, and mechanical properties were quantified. In addition, the experiments were carried out under different temperatures and humidity conditions to explore the macroscopic splitting tensile property of the composites and further validate the MD results. The MD results suggest that the Ca ions on the C-S-H surface are crucial to the adhesion by forming Ca−O and Ca−N bonds with epoxy. However, these bonds were reduced in the presence of water molecules, with a reduction also of the interfacial energy. The degradation effects are exacerbated by the presence of NaCl solution, as Na ions gather around the interfacial region of C-S-H/ epoxy, further accumulating water molecules by forming hydrated ion clusters. This process is accelerated by elevated temperature. The experiment results suggest that without the influence of NaCl solution, a moist C-S-H surface turns to gain a stronger bonding with epoxy when the curing temperature is higher (40, 60 °C). Meanwhile, the bonding properties of a dry C-S-H surface and epoxy are less sensitive to temperature. This work provides new insight into understanding the bonding mechanism on the C-S-H/epoxy interface and may benefit the engineering application of CFRP-concrete reinforcement.

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Preferred orientation of calcium aluminosilicate hydrate compacts: Implications for creep and indentation

Cited by 49 publications

References 78 publications

Experimental study on basic and drying creep for an alkali‐activated slag concrete and comparison with existing creep models

Experimental study on basic and drying creep for an alkali‐activated slag concrete and comparison with existing creep models

Nanoscale Prediction of the Thermal, Mechanical, and Transport Properties of Hydrated Clay on 10⁶- and 10¹⁵-Fold Larger Length and Time Scales

Interfacial Degradation of Calcium Silicate Hydrate and Epoxy under a Hygrothermal Environment: An Experimental and Molecular Model Study

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Preferred orientation of calcium aluminosilicate hydrate compacts: Implications for creep and indentation

Cited by 49 publications

References 78 publications

Experimental study on basic and drying creep for an alkali‐activated slag concrete and comparison with existing creep models

Experimental study on basic and drying creep for an alkali‐activated slag concrete and comparison with existing creep models

Nanoscale Prediction of the Thermal, Mechanical, and Transport Properties of Hydrated Clay on 106- and 1015-Fold Larger Length and Time Scales

Interfacial Degradation of Calcium Silicate Hydrate and Epoxy under a Hygrothermal Environment: An Experimental and Molecular Model Study

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Nanoscale Prediction of the Thermal, Mechanical, and Transport Properties of Hydrated Clay on 10⁶- and 10¹⁵-Fold Larger Length and Time Scales