scholarly journals Geometrical Modeling of Concrete Microstructure for the Assessment of ITZ Percolation

10.14311/1674 ◽  
2012 ◽  
Vol 52 (6) ◽  
Author(s):  
Daniel Rypl ◽  
Tomáš Bým
Keyword(s):  
Transport Properties ◽  
Hard Core ◽  
Critical Factor ◽  
Interfacial Transition Zone ◽  
Constant Thickness ◽  
Geometrical Modeling ◽  
Multiphase Materials ◽  
And Topology ◽  
Soft Shell ◽  
Aggregate Particles

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.

Digital-Image-Based Computer Modeling and Visualization of Cement-Based Materials

1996 ◽  
Vol 1526 (1) ◽  
pp. 129-134
Author(s):  
Dale P. Bentz ◽  
Edward J. Garboczi
Keyword(s):  
Computer Modeling ◽  
Cement Paste ◽  
Digital Image ◽  
Hard Core ◽  
Percolation Model ◽  
Interfacial Transition Zone ◽  
The Past ◽  
Cement Based Materials ◽  
Soft Shell ◽  
Modeling Techniques

Over the past several years, digital-image-based computer models and subsequent visualization of microstructure have proven valuable in studying processing-microstructure-property relationships in cement-based materials. This paper reviews the computer modeling techniques used to simulate the microstructure of hydrating cement paste at the micrometer level and the microstructure of concrete and mortar at the millimeter level. In the former case, digital-image-based models using cellular automata offer many advantages in simulating the reactions occurring during the hydration of cement paste. In the latter case, a continuum hard core-soft shell percolation model appears to be most efficient for modeling the aggregates in a mortar or concrete, each surrounded by an interfacial transition zone (ITZ). Here, digitization is employed to compute the volume fractions occupied by aggregate, bulk cement paste, and ITZ cement paste. The influence of microstructure on the diffusivity of these materials is addressed within the overall framework of this multiscale modeling approach.

Interfacial Zone Percolation in Concrete: Effects of Interfacial Zone Thickness and Aggregate Shape

1994 ◽  
Vol 370 ◽  
Author(s):  
D.P. Bentz ◽  
J.T.G. Hwang ◽  
C. Hagwood ◽  
E.J. Garboczi ◽  
K.A. Snyder ◽  
...  
Keyword(s):  
Transition Zone ◽  
High Performance ◽  
Dynamic Range ◽  
Hard Core ◽  
Concrete Specimen ◽  
Interfacial Transition Zone ◽  
Interfacial Zone ◽  
Transition Zones ◽  
Soft Shell ◽  
Aggregate Shape

AbstractPreviously, a hard core/soft shell computer model was developed to simulate the overlap and percolation of the interfacial transition zones surrounding each aggregate in a mortar or concrete. The aggregate particles were modelled as spheres with a size distribution representative of a real mortar or concrete specimen. Here, the model has been extended to investigate the effects of aggregate shape on interfacial transition zone percolation, by modelling the aggregates as hard ellipsoids, which gives a dynamic range of shapes from plates to spheres, to fibers. For high performance concretes, the interfacial transition zone thickness will generally be reduced, which will also affect their percolation properties. This paper presents results from a study of the effects of interfacial transition zone thickness and aggregate shape on these percolation characteristics.

scholarly journals The pollen tube: a soft shell with a hard core

2012 ◽  
Vol 73 (4) ◽  
pp. 617-627 ◽  
Author(s):  
Hannes Vogler ◽  
Christian Draeger ◽  
Alain Weber ◽  
Dimitris Felekis ◽  
Christof Eichenberger ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Hard Core ◽  
Soft Shell

scholarly journals Structural optimization in ESAC: annals 2011

2014 ◽  
Vol 5 ◽  
pp. A09
Author(s):  
Ji-Hong Zhu ◽  
Wei-Hong Zhang
Keyword(s):  
Topology Optimization ◽  
Structural Optimization ◽  
Material Properties ◽  
Numerical Results ◽  
Multiphase Materials ◽  
And Topology ◽  
Effective Material Properties

The purpose of this paper is to give an overall introduction of the structural optimization research works in ESAC group in 2011. Four main topics are involved, i.e. 1) topology optimization with multiphase materials, 2) integrated layout and topology optimization, 3) prediction of effective material properties and 4) composite design. More detailed techniques and some numerical results are also presented and discussed here.

A Study of the Mass Transport Resistance of Glucose Across Rat Capsular Membranes

1987 ◽  
Vol 110 ◽  
Author(s):  
C. L. Freeman ◽  
K. G. Mayhan ◽  
G. J. Picha ◽  
C. K. Colton
Keyword(s):  
Connective Tissue ◽  
Mass Transport ◽  
Transport Properties ◽  
Critical Factor ◽  
Giant Cells ◽  
Fibrous Connective Tissue ◽  
Initial Attempt ◽  
Implant Surface ◽  
Tissue Factors ◽  
Foreign Surface

The interaction between a polymer or other foreign surface and soft tissue is determined by a variety of materials and tissue factors. After failing to engulf the foreign body, the classical response is to wall it off. First the site is invaded by macrophages and giant cells and then fibrous connective tissue is laid down. This fibrous connective tissue gradually replaces the cellular matrix and forms the capsule. The composition is mostly collagen and mucopolysaccharides with few cells in the mature capsule. It contains 75–80% water.When the implant surface represents a sensor and the transport of low molecular weight species across the capsule is necessary for meaningful measurement and response time, the mass transport resistance of the capsule may become a critical factor. This study represents an initial attempt to characterize the diffusion of glucose through fibrous capsules grown around silicone elastomer implants in a rat. Specifically, the study was designed to develop techniques to measure mass transport properties of tissue capsules, to use these techniques to determine effective glucose transport properties at two weeks, four weeks, and ten weeks after implant; and, to use these results along with histological examinations to gain an understanding of the factors which influence mass transport.

scholarly journals Waterlike anomalies in hard core–soft shell nanoparticles using an effective potential approach: Pinned vs adsorbed polymers

2020 ◽  
Vol 127 (5) ◽  
pp. 054701 ◽  
Author(s):  
Murilo S. Marques ◽  
Thiago P. O. Nogueira ◽  
Rodrigo F. Dillenburg ◽  
Marcia C. Barbosa ◽  
José Rafael Bordin
Keyword(s):  
Effective Potential ◽  
Hard Core ◽  
Shell Nanoparticles ◽  
Potential Approach ◽  
Soft Shell ◽  
Adsorbed Polymers

A DEM hard-core soft-shell model for the simulation of concrete flow

2014 ◽  
Vol 58 ◽  
pp. 169-178 ◽  
Author(s):  
Sebastien Remond ◽  
Patrick Pizette
Keyword(s):  
Shell Model ◽  
Hard Core ◽  
Soft Shell ◽  
Concrete Flow

Effects of Interfacial Zone Percolation on Cement-Based Composite Transport Properties

1991 ◽  
Vol 245 ◽  
Author(s):  
K.A. Snyder ◽  
D.N. Winslow ◽  
D.P. Bentz ◽  
E.J. Garboczi
Keyword(s):  
Computer Simulation ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Transport Properties ◽  
Volume Fraction ◽  
Cement Mortar ◽  
Mercury Porosimetry ◽  
Computer Simulation Model ◽  
Interfacial Zone ◽  
Aggregate Particles

ABSTRACTIn portland cement mortar and concrete, interfacial zones exist around the aggregate particles that have larger pore sizes and pore volumes than the bulk cement paste. If there are enough aggregate particles present, these zones may overlap so as to percolate. A computer simulation model has been developed that can predict this percolation point as a function of interfacial zone thickness, volume fraction of aggregates, and aggregate particle size distribution. The model was used to simulate 1cm3 of mortar, using approximately 10,000 aggregate particles. Results from this model are used to explain recent mercury porosimetry results on mortars having a variety of sand contents. The implications of interfacial zone percolation for the transport properties of mortar and concrete are discussed.

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