Application of Digital-Image-Based Models to Microstructure, Transport Properties, and Degradation of Cement-Based Materials.

As multi-phase composites, cement-based materials have physical properties that are strongly influenced by the volume fractions and topologies of the individual phases. Because of their inherent random nature, these materials often defy a simple geometrical description. The use of digital-image-based models allows one to realistically represent this class of materials, as resultant microstructures can be quickly quantified with respect to the volume fraction and interconnectivity or percolation of each phase or any combination of phases. In addition, physical properties such as diffusivity and permeability can be conveniently computed using finite-difference or finite-element techniques. These computer modelling techniques will be demonstrated for microstructural models of these materials at two scales: hydrated cement paste at the micrometer level and calcium silicate hydrate gel at the nanometer level. The properties computed for the gel at the nanometer level can be used as input for the micrometer-level model. Examples of the importance of volume fraction and phase topology in determining physical properties will be presented for each of the four major phases of cement paste: anhydrous cement, capillary porosity, calcium silicate hydrate gel, and calcium hydroxide. Results of the models are compared to existing experimental data, and good agreement is observed. These techniques are seen as one critical link in developing sound scientific relationships between the microstructure and the transport properties and durability of cement-based materials.

[1]  Peter V. Coveney,et al.  Cellular automaton simulations of cement hydration and microstructure development , 1994 .

[2]  A Scaling Model of the Microstructural Evolution in C3S/C-S-H Pastes , 1996 .

[3]  Zdeněk P. Bažant,et al.  Creep and Shrinkage of Concrete , 1965, Nature.

[4]  T. Powers,et al.  Absorption of Water by Portland Cement Paste during the Hardening Process , 1935 .

[5]  S. Redner,et al.  Introduction To Percolation Theory , 2018 .

[6]  A. Allen,et al.  Development of the fine porosity and gel structure of hydrating cement systems , 1987 .

[7]  Véronique Baroghel-Bouny,et al.  Caractérisation microstructurale et hydrique des pâtes de ciment et des bétons ordinaires et à très hautes performances , 1994 .

[8]  I. Odler,et al.  On the origin of Portland cement setting , 1992 .

[9]  Z. Hashin.  Analysis of Composite Materials—A Survey , 1983 .

[10]  P. Gegout,et al.  Effect of pH on the durability of cement pastes , 1992 .

[11]  K. Van Breugel,et al.  Simulation of hydration and formation of structure in hardening cement-based materials , 1991 .

[12]  Edward J. Garboczi,et al.  Computational materials science of cement-based materials , 1993 .

[13]  Arnon Bentur,et al.  Materials science of concrete IV: Edited by J. Skalny and S. Mindess, The American Ceramic Society, 1995 , 1995 .

[14]  Interpretation of impedance spectroscopy of cement paste via computer modelling , 1995, Journal of Materials Science.

[15]  Jeff R. Wright,et al.  Digital Image Processing: Techniques and Applications in Civil Engineering , 1993 .

[16]  E. Garboczi,et al.  Computer simulation of the diffusivity of cement-based materials , 1992 .

[17]  E. Garboczi,et al.  Modelling the leaching of calcium hydroxide from cement paste: effects on pore space percolation and diffusivity , 1992 .

[18]  P. Stutzman.  Serial sectioning of hardened cement paste for scanning electron microscopy , 1990 .

[19]  Schwartz,et al.  Cross-property relations and permeability estimation in model porous media. , 1993, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[20]  Dale P. Bentz,et al.  Digital-Image-Based Computer Modelling of Cement-Based Materials , 1993 .

[21]  Edward J. Garboczi,et al.  Percolation of phases in a three-dimensional cement paste microstructural model , 1991 .

[22]  T. C. Powers,et al.  Structure and Physical Properties of Hardened Portland Cement Paste , 1958 .

[23]  Nicos Martys,et al.  Transport and diffusion in three-dimensional composite media , 1994 .

[24]  E. Garboczi,et al.  Water permeability and chloride ion diffusion in portland cement mortars: Relationship to sand content and critical pore diameter , 1995 .

[25]  L. Struble,et al.  Microstructural development during hydration of cement , 1987 .

[26]  Peter V. Coveney,et al.  Ultrasonic measurements on hydrating cement slurries: Onset of shear wave propagation , 1995 .

[27]  E. Garboczi,et al.  X-Ray Microtomography of an Astm C109 Mortar Exposed to Sulfate Attack , 1994 .

[28]  H. Jennings,et al.  Simulation of Microstructure Development During the Hydration of a Cement Compound , 1986 .

[29]  B. Flannery,et al.  Three-Dimensional X-ray Microtomography , 1987, Science.

[30]  Transport and diffusion in porous media: computation at the interface between physics and geometry , 1997 .

[31]  Edward J. Garboczi,et al.  Modelling drying shrinkage of cement paste and mortar Part 1. Structural models from nanometres to millimetres , 1995 .