Capabilities for property assessment on different levels of the micro-structure of DEM-simulated cementitious materials

Abstract Realistic three-scale simulation by DEM of particulate materials like concrete is nowadays possible by fast developments in computer technology. This would be an attractive alternative for systematic physical experimenting that is more time-consuming, labour-intensive and thus expensive. The paper discusses the simulation on meso-level of the aggregate structure and on micro-level of the fresh binder material that is enclosed by aggregate grains. In the latter case, it will be followed by hydration simulation to obtain the matured material. This can be expanded to involve particle packing of the C–S–H on nano-level, completing the three-scale approach. For assessment of mechanical properties, packing density is a crucial issue that can be straightforwardly studied. A subject of major engineering relevance is porosity because of durability issues. This requires techniques for delineating the capillary pore network structure to be able assessing its topological and geometric properties. By combining such features with hydraulic properties in a so called tube network model, basically transport properties of concrete can be estimated that are underlying long-term strength issues. Influences of technological parameters on packing characteristics are of interest for optimising packing, strength and durability of cementitious composites. The paper will offer the main lines of a complete methodology involving a modern three-scale analogue DEM approach, hydration simulation, and pore delineation and measuring. Intension is not to discuss separate “building blocks” of the methodology, because they have been presented, discussed and validated earlier in publications. Additionally, typical capabilities of the methodology will be indicated. To do so, results will be presented for illustrative purposes on the shape issue involved in aggregate packing, on the positive effects of cement blending by fine-grained rice husk ash on pore characteristics and resulting permeability, and on permeability estimation in the practical case of pores containing capillary water.

[1]  Jing Hu,et al.  Concrete porosimetry: Aspects of feasibility, reliability and economy , 2010 .

[2]  Piet Stroeven,et al.  Particle size effect on the strength of rice husk ash blended gap-graded Portland cement concrete , 2005 .

[3]  Arnon Bentur,et al.  The influence of microfillers on enhancement of concrete strength , 1993 .

[4]  Piet Stroeven,et al.  POROSIMETRY BY DOUBLE-RANDOM MULTIPLE TREE STRUCTURING IN VIRTUAL CONCRETE , 2012 .

[5]  Jeffrey W. Bullard,et al.  Shape analysis of a reference cement , 2004 .

[6]  R. O'Connor,et al.  A distributed discrete element modeling environment: algorithms, implementation and applications , 1996 .

[7]  L. Sluys,et al.  Influence of Particle Packing on Elastic Properties of Concrete , 2012 .

[8]  Zoubeir Lafhaj,et al.  Experimental study of gas and liquid permeability of a mortar , 2002 .

[9]  L. J. Sluys,et al.  Characterization of the packing of aggregate in concrete by a discrete element approach , 2009 .

[10]  H. He,et al.  Computational Modelling of Particle Packing in Concrete , 2010 .

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

[12]  Robert Eymard,et al.  Constitutive modeling of unsaturated drying deformable materials , 1998 .

[13]  John G. Hagedorn,et al.  Three-dimensional shape analysis of coarse aggregates : New techniques for and preliminary results on several different coarse aggregates and reference rocks , 2006 .

[14]  A. Ramezanianpour,et al.  EFFECTS OF VOLUMETRIC AGGREGATE FRACTION ON TRANSPORT PROPERTIES OF CONCRETE AND MORTAR , 2009 .

[15]  Hans-Jörg Vogel,et al.  A numerical experiment on pore size, pore connectivity, water retention, permeability, and solute transport using network models , 2000 .

[16]  David A Lange,et al.  Image-based characterization of cement pore structure using wood’s metal intrusion , 1998 .

[17]  P. Navi,et al.  Three-dimensional characterization of the pore structure of a simulated cement paste , 1999 .

[18]  N. Buenfeld,et al.  Influence of the interfacial transition zone and microcracking on the diffusivity, permeability and sorptivity of cement-based materials after drying , 2009 .

[19]  A. Philipse,et al.  Random packings of spheres and spherocylinders simulated by mechanical contraction. , 2003, Physical review. E, Statistical, nonlinear, and soft matter physics.

[20]  M. Stroeven.  Discrete Numerical Modelling of Composite Materials - application to cementitious materials , 1999 .

[21]  Randall M. German,et al.  Particle packing characteristics , 1989 .

[22]  Z. Tan,et al.  Characterization of ITZ in ternary blended cementitious composites: Experiment and simulation , 2013 .

[23]  D. Bentz.  Three-Dimensional Computer Simulation of Portland Cement Hydration and Microstructure Development , 1997 .

[24]  C. C. Yang,et al.  Approximate migration coefficient of interfacial transition zone and the effect of aggregate content on the migration coefficient of mortar , 2002 .

[25]  L. Sluys,et al.  A novel numerical multi-component model for simulating hydration of cement , 2013 .

[26]  A. Routh,et al.  Growth of sheets in 3D confinements - a model for the C-S-H meso structure , 2014 .

[27]  Mickaël Thiery,et al.  Modelling of isothermal coupled moistureion transport in cementitious materials , 2011 .

[28]  Norman R. Morrow,et al.  Capillary behavior of a perfectly wetting liquid in irregular triangular tubes , 1991 .

[29]  V. T. Nguyen.  Rice husk ash as a mineral admixture for Ultra High performance Concrete , 2011 .

[30]  I. Richardson.  Tobermorite/jennite- and tobermorite/calcium hydroxide-based models for the structure of C-S-H: applicability to hardened pastes of tricalcium silicate, β-dicalcium silicate, Portland cement, and blends of Portland cement with blast-furnace slag, metakaolin, or silica fume , 2004 .

[31]  Hamlin M. Jennings,et al.  A model for the microstructure of calcium silicate hydrate in cement paste , 2000 .

[32]  Piet Stroeven,et al.  On the usefulness of discrete element computer modeling of particle packing for material characterization in concrete technology , 2009 .

[33]  P B Bamforth,et al.  The relationship between permeability coefficients for concrete obtained using liquid and gas , 1987 .

[34]  Luc Courard,et al.  Shape simulation of granular particles in concrete and applications in DEM , 2012 .

[35]  T. Patzek,et al.  Shape Factor and Hydraulic Conductance in Noncircular Capillaries. , 2001, Journal of colloid and interface science.

[36]  M. Carcasses,et al.  Gas permeability of concrete in relation to its degree of saturation , 1999 .

[37]  N. Banthia,et al.  Water permeability of cement paste , 1989 .

[38]  Mingzhong Zhang,et al.  Transport properties in unsaturated cement-based materials – A review , 2014 .

[39]  M. Stroeven,et al.  Influence of Boundary Conditions on Pore Percolation in Model Cement Paste , 2005 .

[40]  L. J. Sluys,et al.  ITZ volume fraction in concrete with spheroidal aggregate particles and application: Part II. Prediction of the chloride diffusivity of concrete , 2011 .

[41]  Shashank Bishnoi,et al.  µic: A New Platform for Modelling the Hydration of Cements , 2009 .

[42]  K. Scrivener,et al.  Densification of C–S–H Measured by 1H NMR Relaxometry , 2013 .

[43]  T. W. Patzek,et al.  Regular ArticleShape Factor and Hydraulic Conductance in Noncircular Capillaries: I. One-Phase Creeping Flow , 2001 .

[44]  Sidney Diamond,et al.  Mercury porosimetry: An inappropriate method for the measurement of pore size distributions in cement-based materials , 2000 .

[45]  F. Stillinger,et al.  Improving the Density of Jammed Disordered Packings Using Ellipsoids , 2004, Science.

[46]  Hamlin M. Jennings,et al.  Refinements to colloid model of C-S-H in cement: CM-II , 2008 .

[47]  A. W. Harris,et al.  Mass transport properties of mature wasteform grouts , 2007 .

[48]  M. Stroeven,et al.  SPACE Approach to Concrete's Space Structure and its Mechanical Properties , 2001 .

[49]  D. Weaire,et al.  Random packing of elliptical disks , 2005 .

[50]  L. Sluys,et al.  Influence of particle packing on fracture properties of concrete , 2011 .

[51]  Piet Stroeven,et al.  Methodological Approaches to 3D Pore Structure Exploration in Cementitious Materials , 2012 .

[52]  A. Khelidj,et al.  Assessment of liquid water and gas permeabilities of partially saturated ordinary concrete , 2014 .

[53]  H. J. G. Gundersen,et al.  The new stereological tools: Disector, fractionator, nucleator and point sampled intercepts and their use in pathological research and diagnosis , 1988, APMIS : acta pathologica, microbiologica, et immunologica Scandinavica.

[54]  P. Navi,et al.  Simulation of cement paste microstructure hydration, pore space characterization and permeability determination , 2005 .

[55]  R. K. Dhir,et al.  Near surface characteristics of concrete: intrinsic permeability , 1989 .

[56]  Mingzhong Zhang,et al.  Modeling of ionic diffusivity in non-saturated cement-based materials using lattice Boltzmann method , 2012 .

[57]  M. Stroeven,et al.  SELF-HEALING CAPACITY OF CONCRETE - COMPUTER SIMULATION STUDY OF UNHYDRATED CEMENT STRUCTURE , 2011 .

[58]  Guang Ye,et al.  Experimental Study and Numerical Simulation of the Development of the Microstructure and Permeability of Cementitious Materials , 2003 .

[59]  A. Nonat,et al.  Hydrated Layer Formation on Tricalcium and Dicalcium Silicate Surfaces: Experimental Study and Numerical Simulations , 2001 .

[60]  Rachel J. Detwiler,et al.  Water permeability and microstructure of three old concretes , 1994 .