Geometrical Modeling of Concrete Microstructure for the Assessment of ITZ Percolation

• Main Authors: Daniel Rypl, Tomáš Bým
• Format: Article
• Language: English
• Published: CTU Central Library 2012-01-01
• Series: Acta Polytechnica
• Subjects: percolation; concrete; interfacial transition zone; aggregates; hard core – soft shell; spherical harmonic analysis
• Online Access: https://ojs.cvut.cz/ojs/index.php/ap/article/view/1674
• ISSN: 1210-2709; 1805-2363

Percolation is considered to be a critical factor affecting the transport properties of multiphase materials. In the case of concrete, the transport properties are strongly dependent on the interfacial transition zone (ITZ), which is a thin layer of cement paste next to aggregate particles. It is not computationally simple to assess ITZ percolation in concrete, as the geometry and topology of this phase is complex. While there are many advanced models that analyze the behavior of concrete, they are mostly based on the use of spherical or ellipsoidal shapes for the geometry of the aggregate inclusions. These simplified shapes may become unsatisfactory in many simulations, including the assessment of ITZ percolation. This paper deals with geometrical modeling of the concrete microstructure using realistic shapes of aggregate particles, the geometry of which is represented in terms of spherical harmonic expansion. The percolation is assessed using the hard core – soft shell model, in which each randomly-placed aggregate particle is surrounded by a shell of constant thickness representing ITZ.