Mechanisms of Phase Transformation and Creating Mechanical Strength in a Sustainable Calcium Carbonate Cement

Calcium carbonate cements have been synthesized by mixing amorphous calcium carbonate and vaterite powders with water to form a cement paste and study how mechanical strength is created during the setting reaction. In-situ XRD was used to monitor the transformation of ACC and vaterite phases into calcite and a rotational rheometer was used to monitor the strength evolution. There are two characteristic time scales of the strengthening of the cement paste. The short timescale of the order 1 hour is controlled by smoothening of the vaterite grains, allowing closer and therefore adhesive contacts between the grains. The long timescale of the order 10-50 hours is controlled by the phase transformation of vaterite into calcite. This transformation is, unlike in previous studies using stirred reactors, found to be mainly controlled by diffusion in the liquid phase. The evolution of shear strength with solid volume fraction is best explained by a fractal model of the paste structure.

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Mechanisms of Phase Transformation and Creating Mechanical Strength in a Sustainable Calcium Carbonate Cement

Materials ◽

10.3390/ma13163582 ◽

2020 ◽

Vol 13 (16) ◽

pp. 3582

Author(s):

Jesús Rodríguez-Sánchez ◽

Teresa Liberto ◽

Catherine Barentin ◽

Dag Kristian Dysthe

Keyword(s):

Phase Transformation ◽

Calcium Carbonate ◽

Mechanical Strength ◽

Cement Paste ◽

Volume Fraction ◽

Solid Volume Fraction ◽

Fractal Model ◽

Amorphous Calcium Carbonate ◽

Carbonate Cement ◽

Carbonate Cements

Calcium carbonate cements have been synthesized by mixing amorphous calcium carbonate and vaterite powders with water to form a cement paste and study how mechanical strength is created during the setting reaction. In-situ X-ray diffraction (XRD) was used to monitor the transformation of amorphous calcium carbonate (ACC) and vaterite phases into calcite and a rotational rheometer was used to monitor the strength evolution. There are two characteristic timescales of the strengthening of the cement paste. The short timescale of the order 1 h is controlled by smoothening of the vaterite grains, allowing closer and therefore adhesive contacts between the grains. The long timescale of the order 10–50 h is controlled by the phase transformation of vaterite into calcite. This transformation is, unlike in previous studies using stirred reactors, found to be mainly controlled by diffusion in the liquid phase. The evolution of shear strength with solid volume fraction is best explained by a fractal model of the paste structure.

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Mechanisms of Phase Transformation and Creating Mechanical Strength in a Sustainable Calcium Carbonate Cement

10.20944/preprints201810.0526.v1 ◽

2018 ◽

Cited By ~ 1

Author(s):

Jesús Rodríguez-Sánchez ◽

Teresa Liberto ◽

Catherine Barentin ◽

Dag Kristian Dysthe

Keyword(s):

Calcium Carbonate ◽

Mechanical Strength ◽

Energy Difference ◽

Amorphous Calcium Carbonate ◽

Carbonate Cement ◽

In Situ Xrd ◽

Carbonate Cements ◽

Size Evolution ◽

Bulk Free Energy ◽

Delta G

Calcium carbonate cements have been synthesized by mixing amorphous calcium carbonate and vaterite powders with water to unravel the mechanisms of creating mechanical strength during the setting reaction. In-situ XRD was used to monitor the transformation of ACC and vaterite phases into calcite. Unlike this transformation of crystals suspended in a stirred solution, the transformation in the cement is controlled by vaterite dissolution. The supersaturation within the cement paste, Ω, depends not only on the bulk free energy difference of the phases, ΔG, but also on the grain size evolution. Among the strengthening mechanisms, an initial geometric reorganization of CaCO3 particles has been identified by rheological measurements; followed by the formation of an interconnected network of calcite crystals that increases in strength as the crystals grow and form bridges among them. All compositions yield microporous calcite structures with diverse transformation history, crystal bridging efficiency, and hence final mechanical properties.

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Phase Transformation of Magnesium Amorphous Calcium Carbonate (Mg-ACC) in a Binary Solution of Ethanol and Water

Crystal Growth & Design ◽

10.1021/cg3008206 ◽

2012 ◽

Vol 13 (1) ◽

pp. 59-65 ◽

Cited By ~ 23

Author(s):

Yang-Yi Liu ◽

Jun Jiang ◽

Min-Rui Gao ◽

Bo Yu ◽

Li-Bo Mao ◽

...

Keyword(s):

Phase Transformation ◽

Calcium Carbonate ◽

Binary Solution ◽

Amorphous Calcium Carbonate

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Phase transformation of amorphous calcium carbonate to single-crystalline aragonite with macroscopic layered structure in the presence of egg white protein and zinc ion

Journal of Wuhan University of Technology-Mater Sci Ed ◽

10.1007/s11595-015-1102-0 ◽

2015 ◽

Vol 30 (1) ◽

pp. 65-70 ◽

Cited By ~ 2

Author(s):

Hui Zeng ◽

Jingjing Xie ◽

Hang Ping ◽

Menghu Wang ◽

Hao Xie ◽

...

Keyword(s):

Phase Transformation ◽

Calcium Carbonate ◽

Layered Structure ◽

Zinc Ion ◽

Egg White ◽

Amorphous Calcium Carbonate ◽

Single Crystalline ◽

Egg White Protein

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An Efficient Approach of Predicting the Elastic Property of Hydrating Cement Paste

Frontiers in Materials ◽

10.3389/fmats.2021.729644 ◽

2021 ◽

Vol 8 ◽

Author(s):

Baoyu Ma ◽

Guansuo Dui ◽

Zhenglin Jia ◽

Bo Yang ◽

Chunyan Yang ◽

...

Keyword(s):

Elastic Properties ◽

Cement Paste ◽

Volume Fraction ◽

Solid Volume Fraction ◽

Empirical Method ◽

Elastic Behavior ◽

Engineering Practice ◽

Proposed Model ◽

Hydration Model ◽

Semi Empirical

Although elastic properties of hydrating cement paste are crucial in concrete engineering practice, there are only a few widely available models for engineers to predict the elastic behavior of hydrating cement paste. Therefore, in this paper, we derive an analytical model to efficiently predict the elastic properties (e.g., Young’s modulus) of hydrating cement paste. Notably, the proposed model provides the prediction of hydration, percolation, and homogenization of the cement paste, enabling the study of the early age elasticity evolution in cement paste. A hydration model considering the mineral composition and the initial w/c ratio was used, while the percolation threshold was calculated adopting a phenomenological semi-empirical method describing the effects of the solid volume fraction and the w/c ratio. An efficient mixing rule based on the degree of solid connectivity was then adopted to calculate the elastic properties of the hydrating cement paste. Moreover, for ordinary Portland cement, a simplified model was built using Powers’ hydration model. The obtained modeling results are following experimental data and other numerical results available in the literature.

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Microstructure and Relative Humidity Effects on Long-Term Indentation Creep Properties of Calcium Carbonate Cement

10.20944/preprints201810.0671.v1 ◽

2018 ◽

Cited By ~ 2

Author(s):

Jesús Rodríguez-Sánchez ◽

Qing Zhang ◽

Dag Kristian Dysthe

Keyword(s):

Elastic Modulus ◽

Calcium Carbonate ◽

Relative Humidity ◽

Indentation Creep ◽

Amorphous Calcium Carbonate ◽

Creep Properties ◽

Carbonate Cement ◽

Creep Modulus ◽

Term Creep

This paper addresses the effect of both microstructure and relative humidity on the long-term creep properties of sustainable calcium carbonate (CaCO3) cements. Those can be prepared by mixing amorphous calcium carbonate and vaterite with water. A larger starting amount of vaterite, XV, within the mixture design gives a higher elasticity and resistance to the specimens due to the larger overall bridging area within the newly formed calcite crystals. Regarding creep properties for a given relative humidity, the amplitude of creep strain decreases with XV, and makes the relation between the elastic modulus, E, and hardness, H, of the samples to be linear with the contact creep modulus, C. On the other hand, for a given composition, the amplitude of creep increases with the relative humidity, making the contact creep modulus, Ci, to rise exponentially with the elastic modulus, E, and hardness, H, of the specimens. The most probable creep mechanisms for this kind of cement seem to be a combination of microcraking in the early stages and dissolution and reprecipitation of calcite in the long-term (also known as pressure solution theory). The presence of water in pores with increasing relative humidity might enhance the local dissolution of calcite, and hence the creep amplitude.

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Pressure-driven fusion of amorphous particles into integrated monoliths

Science ◽

10.1126/science.abg1915 ◽

2021 ◽

Vol 372 (6549) ◽

pp. 1466-1470

Author(s):

Zhao Mu ◽

Kangren Kong ◽

Kai Jiang ◽

Hongliang Dong ◽

Xurong Xu ◽

...

Keyword(s):

Calcium Carbonate ◽

Mechanical Strength ◽

Applied Pressure ◽

Bound Water ◽

External Pressure ◽

Temperature Sensitive ◽

Mass Transportation ◽

Amorphous Calcium Carbonate ◽

Amorphous Particles ◽

Biological Organisms

Biological organisms can use amorphous precursors to produce inorganic skeletons with continuous structures through complete particle fusion. Synthesizing monoliths is much more difficult because sintering techniques can destroy continuity and limit mechanical strength. We manufactured inorganic monoliths of amorphous calcium carbonate by the fusion of particles while regulating structurally bound water and external pressure. Our monoliths are transparent, owing to their structural continuity, with a mechanical strength approaching that of single-crystal calcite. Dynamic water channels within the amorphous bulk are synergistically controlled by water content and applied pressure and promote mass transportation for particle fusion. Our strategy provides an alternative to traditional sintering methods that should be attractive for constructing monoliths of temperature-sensitive biominerals and biomaterials.

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