Micro-level Porosimetry of Virtual Cementitious Materials Structural Impact on Mechanical and Durability Evolution Luong Bao Nghi Le Micro-level Porosimetry of Virtual Cementitious Materials Structural Impact on Mechanical and Durability Evolution Proefschrift ter verkrijging van de graad van doctor aan de Technische Universiteit Delft, op gezag van de Rector Magnificus prof.ir K.C.A.M Luyben; voorzitter van het College voor Promoties, in het openbaar te verdedigen op maandag 19 oktober 2015 om 12:30 uur door Luong Bao Nghi LE Master of Engineering, Structural Engineering, Ho Chi Minh City University of Technology, Vietnam geboren te Da Lat, Vietnam -i- This dissertation has been approved by the promotor: Prof.dr.ir L.J Sluys Composition of the doctoral committee: Rector Magnificus chairman Prof.dr.ir L.J Sluys Delft University of Technology Independent members: Prof.dr V Mechtcherine Dresden University of Technology Prof.dr.ir N De Belie Ghent University Prof.dr.ir H.J.H Brouwers Eindhoven University of Technology Prof.dr.ir E Schlangen Delft University of Technology Prof.dr.ir K van Breugel Delft University of Technology, reserve member Other members: Dr.ir P Stroeven Delft University of Technology Dr.ir M Stroeven Delft University of Technology Copyright ©2015 by Luong Bao Nghi Le All rights reserved No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic, mechanical, including photocopying, recording or by any information storage and retrieval system, without the prior permission of the author ISBN: 978-94-6186-534-2 Author email: nghi.l.b.le@gmail.com Table of contents TABLE OF CONTENTS .III SUMMARY VII SAMENVATTING IX LIST OF ABBREVIATIONS XI CHAPTER INTRODUCTION 1.1 Concrete as a particulate and porous material at different levels of its microstructure 1.2 Pore characteristics and porosimetries 1.3 Virtual cementitious materials 1.3.1 Drawback of experimental porosimetries 1.3.2 Computational simulation of cementitious materials 1.3.3 Porosimetries applied to virtual cementitious materials 1.4 Objectives and outlines of this research work 1.4.1 Objectives of research 1.4.2 Outlines of research 13 CHAPTER MICROSTRUCTURAL SIMULATION OF HYDRATED CEMENTITIOUS MATERIALS 17 2.1 Introduction 18 2.1.1 Production and composition of cement 18 2.1.2 Particle size distribution and fineness of cement 19 2.1.3 Water to cement ratio 19 2.1.4 Cement hydration 20 2.1.5 Pozzolanic admixtures 22 2.2 Packing simulation of fresh (blended) cement paste 23 2.2.1 Generation of particles 23 2.2.2 Packing simulation by dynamic DEM 26 2.3 Hydration simulation of (blended) cement paste 27 2.3.1 Formation of eXtended Integrated Particle Kinetics Model 28 2.3.2 Equivalent mono-sized fine particles 35 2.3.3 Algorithmic aspects 36 2.3.4 Numerical estimation of the basic penetration rate of hydration front 39 2.4 Verifications 41 - iii - 2.5 Conclusions and discussion 45 CHAPTER COMPUTATIONAL POROSIMETRY FOR VIRTUAL POROUS MATERIALS 47 3.1 Pore characteristics 48 3.1.1 Porosity 48 3.1.2 Degree of connectivity 48 3.1.3 Specific surface area 49 3.1.4 Pore size distribution 49 3.1.5 Porosity gradient and interfacial transition zone 50 3.2 Pore size estimation 50 3.2.1 Star volume measure 50 3.2.2 Application of star volume measure to 3D virtual pore structure 51 3.2.3 Pore throat estimation 52 3.2.4 Enhancement of star volume measure 52 3.3 Random node structuring (RaNoS) 53 3.3.1 Algorithm 53 3.3.2 Characterization of pore structure by RaNoS 54 3.3.3 Localized and parallel computing 57 3.3.4 Examples 58 3.4 Summary 63 CHAPTER PERMEABILITY ESTIMATION FOR A VIRTUAL POROUS MEDIUM 65 4.1 Permeability 66 4.2 Stokes mixed FEM approach 66 4.2.1 Governing equations and weak forms 66 4.2.2 Boundary conditions 67 4.2.3 Mixed FEM Discretization 68 4.2.4 Admissible element 70 4.2.5 Solving the linear equation system 71 4.2.6 Examples 72 4.3 Double-Random Multiple Tree Structuring (DRaMuTS) 74 4.3.1 Algorithm 75 4.3.2 Extraction of main trunks from percolated trees 78 4.3.3 Flow estimation by ‘tube model’ 81 4.3.4 Examples 85 4.4 Summary 88 CHAPTER INVESTIGATION OF PORE CHARACTERISTICS AND PERMEABILITY OF CEMENTITIOUS MATERIALS 91 5.1 Existence of RVE on the aspect of pore characteristics of cementitious materials 92 5.2 Effect of rice husk ash blending 97 5.3 Experiments 98 5.3.1 Input parameters 98 5.3.2 Porosity evolution with hydration time 99 5.3.3 Porosity gradient 100 5.3.4 Pore size distribution 101 5.3.5 Permeability 104 5.3.6 Discussion 106 5.4 Summary 112 CHAPTER MICRO-MECHANICAL BEHAVIOUR OF CEMENTITIOUS MATERIALS 115 6.1 Methodology 116 6.1.1 Assessment of elastic moduli of matured cement pastes 116 6.1.2 2D representative specimen for mechanical tests 117 6.1.3 Tensile test configuration 120 6.1.4 Micro-macro transition 121 6.2 Existence of RVE in tensile damage response of cementitious materials 123 6.3 Parameter study results 125 6.3.1 Young’s modulus 125 6.3.2 Tensile damage response 128 6.4 Summary 135 CHAPTER CONCLUSIONS AND RECOMMENDATIONS 137 7.1 Conclusion 137 7.2 Recommendations 140 REFERENCES 143 ACKNOWLEDGMENTS 155 LIST OF RELEVANT PUBLICATION 157 CURRICULUM VITAE 159 -v- Summary Understanding the microstructure of cement paste is the basis of a study towards properties and behaviour of cementitious materials It is attractive exploiting modern computer facilities for this purpose, favourably competing with time-consuming and laborious experimental approaches This study aims at bringing material studies into virtual reality through a comprehensive computational framework that is composed of three parts as described below The first part deals with generating virtual representations of hardening cement composites at micro-scale, starting with producing a paste of randomly packed cement grains at the fresh state A DEM-based dynamic packing process is used for this purpose to obtain, not only paste with high density but also that with a wide particle size range The next stage involves simulation of the microstructure during hydration, based on an improved version of the well-known vector approach The proposed model denoted ‘eXtended Integrated Particle Kinetics Method’ (XIPKM) includes the following improvements: a multi-component particle model to take major cement compounds and the pozzolan into account, a numerical technique to capture the complex contact between expanding particles (a crucial issue in vector approaches), and finally a concept to avoid the extreme computational effort in generating a very large amount of fine particles Furthermore, a numerical procedure is proposed to obtain the basic penetration rates of different minerals instead of using a laborious calibration process commonly used in vector approaches In the second part, two computational porosimetry methods to explore the pore network characteristics are developed The first method denoted ‘Random Node Structuring’ (RaNoS) characterises the pore space, based on analysing the configuration of a system of random points dispersed in the pore space These random points are further employed, together with an enhanced version (for a more efficient size assessment of irregular pores) of the well-known stereological technique – star volume measure (SVM), to estimate the pore size distribution The second porosimetry method named ‘Double-Random Multiple Tree Structuring’ (DRaMuTS) is an enhanced version of RaNoS, whereby the topology of the pore structure is further efficiently explored by a system of concurrent virtual trees growing and branching randomly in pore space, configured by a robotics-inspired path planning algorithm Based on topological information attained by the tree systems, the pore space is then converted into a cylindrical tube network for directly estimating permeability Based on the pore configuration obtained by the porosimetry methods, 2D representative samples to study the tensile damage response of porous materials in bulk as well as interfacial transition zone (ITZ) are proposed, whereby extremely demanding 3D FEM modelling is dismissed but the impact of the 3D pore space is nevertheless taken into account In the final part, several tests are carried out on cement pastes with/without blended pozzolanic admixtures, i.e rice husk ash (RHA) by applying the presented methodologies, aiming at assessment of the impact of different design parameters - vii - References [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] 145 Wang, Z.M., Kwan, A.K.H and Chan, H.C., Mesoscopic study of concrete I: generation of random aggregate structure and finite element mesh Computers & Structures 70 (1999) 533-544 Satoh, A., Yamada, K and Ishiyama, S., Simplified two-dimensional mesoscopic model for evaluating mechanical properties and crack paths near interfaces in concrete Engineering Fracture Mechanics 108 (2013) 222-237 Häfner, S., Eckardt, S., Luther, T and Könke, C., Mesoscale modeling of concrete: Geometry and numerics Computers & Structures 84 (2006) 450461 Wriggers, P and Moftah, S.O., Mesoscale models for concrete: Homogenisation and damage behaviour Finite Elements in Analysis and Design 42 (2006) 623-636 Kwan, A.K.H., Wang, Z.M and Chan, H.C., Mesoscopic study of concrete II: nonlinear finite element analysis Computers & Structures 70 (1999) 545556 Lee, K.M and Park, J.H., A numerical model for elastic modulus of concrete considering interfacial transition zone Cement and Concrete Research 38 (2008) 396-402 Zhou, X.Q and Hao, H., Mesoscale modelling of concrete tensile failure mechanism at high strain rates Computers & Structures 86 (2008) 20132026 Kim, H and Buttlar, W.G., Discrete fracture modeling of asphalt concrete International Journal of Solids and Structures 46 (2009) 2593-2604 You, Z and Buttlar, W., Discrete element modeling to predict the modulus of asphalt concrete mixtures Journal of Materials in Civil Engineering 16 (2004) 140-146 Bažant, Z., Tabbara, M., Kazemi, M and Pijaudier‐Cabot, G., Random particle model for fracture of aggregate or fiber composites Journal of Engineering Mechanics 116 (1990) 1686-1705 Eliáš, J and Stang, H., Lattice modeling of aggregate interlocking in concrete International Journal of Fracture 175 (2012) 1-11 Leite, J.P.B., Slowik, V and Mihashi, H., Computer simulation of fracture processes of concrete using mesolevel models of lattice structures Cement and Concrete Research 34 (2004) 1025-1033 Lin, F., Modeling of hydration kinetics and shrinkage of portland cement paste PhD thesis, Columbia University, New York, 2006 Basma, A.A., Barakat, S and Al-Oraimi, S., Prediction of cement degree of hydration using artificial neural networks ACI Materials Journal 96 (1999) 167-172 Cervera, M., Faria, R., Oliver, J and Prato, T., Numerical modelling of concrete curing, regarding hydration and temperature phenomena Computers & Structures 80 (2002) 1511-1521 Schindler, A.K and Folliard, K.J., Heat of hydration models for cementitious materials ACI Materials Journal 102 (2005) 24-33 146 References [47] Bentz, D.P., Influence of water-to-cement ratio on hydration kinetics: Simple models based on spatial considerations Cement and Concrete Research 36 (2006) 238-244 Bentz, D.P., Three-dimensional computer simulation of portland cement hydration and microstructure development Journal of American Ceramic Society 80 (1997) 3-21 Bishnoi, S and Scrivener, K.L., µic: A new platform for modelling the hydration of cements Cement and Concrete Research 39 (2009) 266-274 Jennings, H.M and Johnson, S.K., Simulation of microstructure development during the hydration of a cement compound Journal of American Ceramic Society 69 (1986) 790-795 Maruyama, I., Matsushita, T and Noguchi, T., Numerical modeling of Portland cement hydration based on particle kinetic model and multicomponent concept Proceedings of the 12th International Congress of the Chemistry of Cement (ICCC), Montréal, Canada, 2007 Navi, P and Pignat, C., Simulation of cement hydration and the connectivity of the capillary pore space Advanced Cement Based Materials (1996) 5867 Nguyen , V.T., Modeling the hydration of cement blended with rice husk ash Proceedings of the 13th International Congress on the Chemistry of Cement (ICCC), Madrid, Spain, 2011, 353 Stroeven, P and Stroeven, M., Reconstructions by SPACE of the Interfacial Transition Zone Cement and Concrete Composites 23 (2001) 189-200 van Breugel, K., Numerical simulation of hydration and microstructural development in hardening cement-based materials (I) theory Cement and Concrete Research 25 (1995) 319-331 Nguyen, V.P., Micromechanical modelling of concrete Proceedings of Computational Modelling of concrete structures, EURO-C 2010, Schladming, Austria, Taylor & Francis Group, 2010, 547-552 Bernard, O., Ulm, F.-J and Lemarchand, E., A multiscale micromechanicshydration model for the early-age elastic properties of cement-based materials Cement and Concrete Research 33 (2003) 1293-1309 Constantinides, G and Ulm, F.-J., The effect of two types of C-S-H on the elasticity of cement-based materials: Results from nanoindentation and micromechanical modeling Cement and Concrete Research 34 (2004) 67-80 Hain, M and Wriggers, P., Numerical homogenization of hardened cement paste Computational Mechanics 42 (2008) 197-212 Hain, M and Wriggers, P., Computational homogenization of microstructural damage due to frost in hardened cement paste Finite Elements in Analysis and Design 44 (2008) 233-244 Haecker, C.J., Garboczi, E.J., Bullard, J.W., Bohn, R.B., Sun, Z., Shah, S.P and Voigt, T., Modeling the linear elastic properties of Portland cement paste Cement and Concrete Research 35 (2005) 1948-1960 Jennings, H.M., A model for the microstructure of calcium silicate hydrate in cement paste Cement and Concrete Research 30 (2000) 101-116 [48] [49] [50] [51] [52] [53] [54] [55] [56] [57] [58] [59] [60] [61] [62] References [63] [64] [65] [66] [67] [68] [69] [70] [71] [72] [73] [74] [75] [76] [77] 147 Tennis, P.D and Jennings, H.M., A model for two types of calcium silicate hydrate in the microstructure of Portland cement pastes Cement and Concrete Research 30 (2000) 855-863 Garboczi, E.J., Concrete Nanoscience and Nanotechnology: Definitions and Applications In: Nanotechnology in Construction 3, Bittnar, Z., Bartos, P.M., Němeček, J., Šmilauer, V and Zeman, J (Eds), 2009 Jennings, H.M and Tennis, P.D., Model for the developing microstructure in Portland cement pastes Journal of American Ceramic Society 77 (1994) 3161-3172 Jennings, H.M., Refinements to colloid model of C-S-H in cement: CM-II Cement and Concrete Research 38 (2008) 275-289 Lindquist, W.B., Lee, S.-M., Coker, D.A., Jones, K.W and Spanne, P., Medial axis analysis of void structure in three-dimensional tomographic images of porous media Journal of Geophysical Research: Solid Earth 101 (1996) 8297-8310 Silin, D.B and Patzek, T.W., Robust determination of the pore space morphology in sedimentary rocks Proceedings of SPE Annual Technical Conference and Exhibition, Colorado, Society of Petroleum Engineers, 2003 Navi, P and Pignat, C., Three-dimensional characterization of the pore structure of a simulated cement paste Cement and Concrete Research 29 (1999) 507-514 Hoshen, J and Kopelman, R., Percolation and cluster distribution I Cluster multiple labeling technique and critical concentration algorithm Physical Review B 14 (1976) 3438-3445 Bentz, D.P and Garboczi, E.J., Percolation of phases in a three-dimensional cement paste microstructural model Cement and Concrete Research 21 (1991) 325-344 Ye, G., Breugel, K.v and Fraaij, A.L.A., Three-dimensional microstructure analysis of numerically simulated cementitious materials Cement and Concrete Research 33 (2003) 215-222 Ye, G., Experimental study and numerical simulation of the development of the micro-structure and permeability of cementitious materials PhD Thesis, Delft University of Technology, Delft University Press, Delft, 2003 Hu, J and Stroeven, P., Depercolation threshold of porosity in model cement: approach by morphological evolution during hydration Cement and Concrete Composites 27 (2005) 19-25 Hu, J and Stroeven, P., Proper characterization of pore size distribution in cementitious materials Key Engineering Materials 302-303 (2006) 479-485 Hilfer, R., Local-porosity theory for flow in porous media Physical Review B 45 (1992) 7115-7121 Hilfer, R., Transport and relaxation phenomena in porous media In: Advances in Chemical Physics, (Eds), 2007 148 References [78] Bentz, D.P., A three-dimensional cement hydration and microstructure program I hydration rate, heat of hydration, and chemical shrinkage NISTIR 5756 U.S Department of Commerce (1995) Bentz, D.P., Modelling cement microstructure: Pixels, particles, and property prediction Materials and Structures 32 (1999) 187-195 Bentz, D.P., CEMHYD3D: A Three-Dimensional Cement Hydration and Microstructure Development Modelling Package, version 2.0, , NISTIR 6485, NIST, 2000 Bentz, D.P., CEMHYD3D: A Three-Dimensional Cement Hydration and Microstructure Development Modelling Package, version 3.0, , NISTIR 7232, NIST, 2005 Bentz, D., P., Coveney, P.V., Garboczi, E., J., Kleyn, M.F and Stutzman, P.E., Cellular automaton simulations of cement hydration and microstructure development Modelling and Simulation in Materials Science and Engineering (1994) 783 van Breugel, K., Simulation of cement hydration and formation of structure in hardening cement based materials PhD Thesis, Delft University of Technology, Delft University Press, Delft, 1991 van Breugel, K., Numerical simulation of hydration and microstructural development in hardening cement-based materials: (II) applications Cement and Concrete Research 25 (1995) 522-530 Koenders, E.A.B., Simulation of volume changes in hardening cement-based materials PhD Thesis, Delft University of Technology, Delft University Press, Delft, 1997 Nguyen, V.T., Rice husk ash as a mineral admixture for ultra high performance concrete PhD Thesis, Delft University of Technology, Ipskamp Drukkers, Delft, 2011 Stroeven, M., Discrete numerical modelling of composite materials application to cementitious materials PhD Thesis, Delft University of Technology, Meinema, Delft, 1999 Navi, P and Pignat, C., Effects of cement size distribution on capillary pore structure of the simulated cement paste Computational Materials Science 16 (1999) 285-293 Hu, J and Stroeven, P., Application of image analysis to assessing critical pore size for permeability prediction of cement paste 2011 22 (2011) Matyka, M., Khalili, A and Koza, Z., Tortuosity-porosity relation in porous media flow Physical Review E 78 (2008) 026306 Duda, A., Koza, Z and Matyka, M., Hydraulic tortuosity in arbitrary porous media flow Physical Review E 84 (2011) 036319 Koponen, A., Kataja, M and Timonen, J., Tortuous flow in porous media Physical Review E 54 (1996) 406-410 Bentz, D.P and Martys, N.S., A Stokes permeability solver for threedimensional porous media NISTIR 7416 U.S Department of Commerce (2007) [79] [80] [81] [82] [83] [84] [85] [86] [87] [88] [89] [90] [91] [92] [93] References [94] [95] [96] [97] [98] [99] [100] [101] [102] [103] [104] [105] [106] [107] [108] 149 Bakke, S and Øren, P.-E., 3-D pore-scale modelling of sandstones and flow simulations in the pore networks Society of Petroleum Engineers (1997) 136-149 Øren, P.-E and Bakke, S., Process based reconstruction of sandstones and prediction of transport properties Transport in Porous Media 46 (2002) 311343 Catalano, E., Chareyre, B., Cortisy, A and Barthelemy, E., A pore-scale hydro-mechanical coupled model for geomaterials Proceedings of II International Conference on Particle-based Methods - Fundamentals and Applications, Barcelona, Oñate, E and Owen, D.R.J (Eds.), Barcelona, 2011 van Eijk, R.J., Hydration of cement mixtures containing contaminants PhD Thesis, University of Twente, Ipskamp Drukkers, Enschede, 2001 Dewar, J., Computer Modelling of Concrete Mixtures Taylor & Francis, London and New York, 2002 Bui, D.D., Rice husk ash as a mineral admixture for high performance concrete PhD Thesis, Delft University of Technology, DUP Science, Delft, 2001 Goldman, A and Bentur, A., The influence of microfillers on enhancement of concrete strength Cement and Concrete Research 23 (1993) 962-972 Diamond, S., Mindess, S and Lovell, J., On the spacing between aggregate grains in concrete and the dimension of the aureole de transition (RILEM publication) Proceedings of Liaisons Pâtes de Ciment/Matériaux Associés, Toulouse, France, 1982, C42-C46 Hu, J., Chen, H and Stroeven, P., Spatial dispersion of aggregate in concrete - a computer simulation study Computers and Concrete (2006) 301-312 Williams, S.R and Philipse, A.P., Random packings of spheres and spherocylinders simulated by mechanical contraction Physical Review E 67 (2003) 051301 Le, L.B.N and Stroeven, P., Strength and durability evaluation by DEM approach of green concrete based on gap-graded cement blending Advanced Materials Research 450-451 (2012) 631-640 Le, L.B.N and Stroeven, P., Porosity of green concrete based on a gapgraded blend Proceedings of Symp Brittle Matrix Comp 10, Warsaw, Brandt, A.M., Olek, J., Glinicki, M.A and Leung, C.K.Y (Eds.), Woodhead Publ Ltd., Cambridge, UK, 2012 Stroeven, P., Le, L.B.N., Sluys, L.J and He, H., Porosimetry by double random multiple tree structuring Image Analysis & Stereology 31 (2012) 55-63 Pignat, C., Navi, P and Scrivener, K., Simulation of cement paste microstructure hydration, pore space characterization and permeability determination Materials and Structures 38 (2005) 459-466 Jennings, H.M and Parrott, L.J., Microstructural analysis of hydrated alite paste, Part 2: Microscopy and reaction products Journal of Materials Science 21 (1986) 4053-4059 150 References [109] Rakhmanov, E.A., Saff, E.B and Zhou, Y.M., Minimal discrete energy on the sphere Mathematical Research Letters (1994) 647–662 [110] Saff, E.B and Kuijlaars, A.B.J., Distributing many points on a sphere The Mathematical Intelligencer 19 (1997) 5-11 [111] Cohen, M.D and Cohen, R.D., Modelling of the hydration of tricalcium silicate Journal of Materials Science 23 (1988) 3816-3820 [112] El-Hemaly, S.A.S., El-Sheikh, R., Mosalamy, F.H and El-Didamony, H., The hydration of alite in the presence of concrete admixtures Thermochimica Acta 78 (1984) 219-225 [113] Escalante-García, J.I and Sharp, J.H., Effect of temperature on the hydration of the main clinker phases in portland cements: part I, neat cements Cement and Concrete Research 28 (1998) 1245-1257 [114] Danielson, U., Heat of hydration of cement as affected by water-cement ratio the 4th International Symposium on the Chemistry of Cement, Washington, 1962, 519-526 [115] Frigione, G and Marra, S., Relationship between particle size distribution and compressive strength in portland cement Cement and Concrete Research (1976) 113-127 [116] Marsh, B.K and Day, R.L., Pozzolanic and cementitious reactions of fly ash in blended cement pastes Cement and Concrete Research 18 (1988) 301-310 [117] Stroeven, P., Le, L.B.N., Sluys, L.J and He, H., Porosimetry by random node structuring in virtual concrete Image Analysis & Stereology 31 (2012) 7987 [118] Bentz, D.P., Stutzman, P.E and Garboczi, E.J., Experimental and simulation studies of the interfacial zone in concrete Cement and Concrete Research 22 (1992) 891-902 [119] Garboczi, E.J and Bentz, D.P., Digital simulation of the aggregate–cement paste interfacial zone in concrete Journal of Materials Research (1991) 196-201 [120] Gundersen, H.J.G., Bendtsen, T.F., Korbo, L., Marcussen, N., MØLler, A., Nielsen, K., Nyengaard, J.R., Pakkenberg, B., SØRensen, F.B., Vesterby, A and West, M.J., Some new, simple and efficient stereological methods and their use in pathological research and diagnosis APMIS 96 (1988) 379-394 [121] Gundersen, H.J.G., Bagger, P., Bendtsen, T.F., Evans, S.M., Korbo, L., Marcussen, N., MØller, A., Nielsen, K., Nyengaard, J.R., Pakkenberg, B., SØRensen, F.B., Vesterby, A and West, M.J., The new stereological tools: Disector, fractionator, nucleator and point sampled intercepts and their use in pathological research and diagnosis Acta Pathologica, Microbiologica et Immunologica Scandinavica 96 (1988) 857-881 [122] Hubbard, P.M., Collision detection for interactive graphics applications Visualization and Computer Graphics, IEEE Transactions on (1995) 218230 [123] Kim, D.-J., Guibas, L.J and Shin, S.-Y., Fast collision detection among multiple moving spheres Visualization and Computer Graphics, IEEE Transactions on (1998) 230-242 References 151 [124] Cuvelier, C., Segal, A and van Steenhoven, A.A., Finite Element Methods and Navier-Stokes Equations Springer, 1986 [125] Peyret, R and Taylor, T.D., Computational methods for fluid flow SpringerVerlag, 1983 [126] Brezzi, F and Fortin, M., Mixed and hybrid finite elements methods Springer-Verlag, 1991 [127] Gresho, P.M., Sani, R.L and Engelman, M.S., Incompressible Flow and the Finite Element Method, Incompressible Flow & the Finite Element Method Advection-Diffusion & Isothermal Laminar Flow Combined Edition (Cloth) John Wiley & Sons, 1998 [128] Fortin, M., Old and new finite elements for incompressible flows International Journal for Numerical Methods in Fluids (1981) 347-364 [129] Langtangen, H.P., Mardal, K.-A and Winther, R., Numerical methods for incompressible viscous flow Advances in Water Resources 25 (2002) 1125– 1146 [130] LaValle, S.M and Kuffner, J.J., Rapidly-exploring random trees: progress and prospects In: Algorithmic and Computational Robotics: New Directions, Donald, B.R., Lynch, K.M and Rus, D (Eds), Wellesley, MA, 2001 [131] Wong, H.S., Zimmerman, R.W and Buenfeld, N.R., Estimating the permeability of cement pastes and mortars using image analysis and effective medium theory Cement and Concrete Research 42 (2012) 476-483 [132] Patzek, T.W and Silin, D.B., Shape factor and hydraulic conductance in noncircular capillaries: I one-phase creeping flow Journal of Colloid and Interface Science 236 (2001) 295-304 [133] Mason, G and Morrow, N.R., Capillary behavior of a perfectly wetting liquid in irregular triangular tubes Journal of Colloid and Interface Science 141 (1991) 262-274 [134] Odler, I and Köster, H., Investigation on the structure of fully hydrated portland cement and tricalcium silicate pastes III Specific surface area and permeability Cement and Concrete Research 21 (1991) 975-982 [135] Banthia, N and Mindess, S., Water permeability of cement paste Cement and Concrete Research 19 (1989) 727-736 [136] Le, L.B.N and Stroeven, P., Effect of blending on properties of pore network structure in blended cements studied in virtual reality Cement and Concrete Composites (2015) (submitted) [137] Gitman, I.M., Representative volumes and multi-scale modelling of quasibrittle materials PhD thesis, Delft University of Technology, Delft, 2006 [138] Nguyen, V.P., Multi-scale failure modelling of quasi-brittle materials PhD Thesis, Delft University of Technology, Ipskamp Drukkers, Enschede, 2011 [139] Stroeven, P., Hu, J and Chen, H., Stochastic heterogeneity as fundamental basis for the design and evaluation of experiments Cement and Concrete Composites 30 (2008) 506-514 [140] Stroeven, P., Hu, J and Stroeven, M., On the usefulness of discrete element computer modeling of particle packing for material characterization in concrete technology Computers and Concrete (2009) 133-153 152 References [141] van Vliet, M.R.A., Size effect of concrete and sandstone Heron 45 (2000) 91-108 [142] van Vliet, M.R.A and van Mier, J.G.M., Experimental investigation of size effect in concrete and sandstone under uniaxial tension Engineering Fracture Mechanics 65 (2000) 165-188 [143] Bažant, Z and Oh, B.H., Crack band theory for fracture of concrete Mat Constr 16 (1983) 155-177 [144] Bažant, Z and Pijaudier‐Cabot, G., Measurement of characteristic length of nonlocal continuum Journal of Engineering Mechanics 115 (1989) 755-767 [145] Stroeven, P and Hu, J., On science aspects of simulating practical manifestations of concrete In: Brittle Matrix Composites 8, Marshall, A.M.B.C.L.H (Eds), 2006 [146] Stroeven, P and Stroeven, M., Size of representative volume element of concrete assessed by quantitative image analysis and computer simulation Image Analysis & Stereology (2001) 216-220 [147] Bui, D.D., Hu, J and Stroeven, P., Particle size effect on the strength of rice husk ash blended gap-graded Portland cement concrete Cement and Concrete Composites 27 (2005) 357-366 [148] He, H., Stroeven, P., Pirard, E and Courard, L., Shape simulation of granular particles in concrete and application in DEM Proceedings of Proc Symp Brittle Matrix Comp 10, Warsaw, 2012 [149] Das, B.B and Kondraivendhan, B., Implication of pore size distribution parameters on compressive strength, permeability and hydraulic diffusivity of concrete Construction and Building Materials 28 (2012) 382-386 [150] Kondraivendhan, B., Divsholi, B.S and Teng, S., Estimation of strength, permeability and hydraulic diffusivity of pozzolana blended concrete through pore size distribution Journal of Advanced Concrete Technology 11 (2013) 230-237 [151] Le, L.B.N., Sluys, L.J., Stroeven, M and Stroeven, P., Implication of pore structure on micro-mechanical behaviour of virtual cementitious materials In: Computational Modelling of Concrete Structures, Bícanić, N., Mang, H., Meschke, G and de Borst, R (Eds), 2014 [152] Hersgey, A., The elasticity of an isotropic aggregate of anisotropic cubic crystals Journal of Applied Mechanics-Transactions of the ASME 21 (1954) 236-240 [153] Kröner, E., Bounds for effective elastic moduli of disordered materials Journal of the Mechanics and Physics of Solids 25 (1977) 137-155 [154] Peerlings, R.H.J., De Borst, R., Brekelmans, W.A.M and De Vree, J.H.P., Gradient enhanced damage for quasi-brittle materials International Journal for Numerical Methods in Engineering 39 (1996) 3391-3403 [155] Mazars, J and Pijaudier‐Cabot, G., Continuum damage theory—application to concrete Journal of Engineering Mechanics 115 (1989) 345-365 [156] Gitman, I.M., Askes, H and Sluys, L.J., Coupled-volume multi-scale modelling of quasi-brittle material European Journal of Mechanics A/Solids 27 (2008) 302-327 References 153 [157] Nguyen, V.P., Lloberas-Valls, O., Stroeven, M and Sluys, L.J., On the existence of representative volumes for softening quasi-brittle materials – A failure zone averaging scheme Computer Methods in Applied Mechanics and Engineering 199 (2010) 3028-3038 [158] Chen, J., Wang, L.-b and Huang, X.-m., Micromechanical modeling of asphalt concrete fracture using a user-defined three-dimensional discrete element method J Cent South Univ 19 (2012) 3595-3602 [159] D’Addetta, G.A., Discrete models for cohesive frictional materials PhD Thesis, University of Stuttgart, Stuttgart, 2011 [160] D'Addetta, G.A., Kun, F and Ramm, E., On the application of a discrete model to the fracture process of cohesive granular materials Granular Matter (2002) 77-90 Acknowledgments The research presented in this dissertation has been carried out in the framework of the PhD programme in the Computational Mechanics group in the Faculty of Civil Engineering and Geosciences of Delft University of Technology, the Netherlands First of all, I would like to express my deep appreciation to my promotor Prof Bert Sluys for his great encouragement, support and guidance throughout my studying, especially in difficult situations I wish to express my extreme gratitude to my ‘daily’ supervisor Prof Piet Stroeven for his enthusiastic inspiration, great assistance and meaningful guidance Also, I am sincerely grateful to my co-supervisor, Dr Martijn Stroeven, for many valuable discussions and careful review of my manuscript I especially thank Frank Everdij for his willing help on my IT problems I would like to express my deep gratitude to Veronique van der Varst, Marjon van der Perk and Anneke Meijer for their thoughtful administrative support I would like to thank my colleagues Angelo Simone, Awais Ahmed, Mehdi Nikbakht, Mojtaba Talebian, Oriol Lloberas Valls, Prithvi Mandapalli, Zahid Shabir, Vinh Phu Nguyen, Frans van der Meer, Rafid Al-Khoury, Adriaan Sillem, Amin Karamnejad, Jitang Fan, Kai Li, Erik Simons, Marcello Malagu and Jaap Weerheijm for friendship and relaxing discussion My special thankfulness goes to Fandi Pawiroredjo for an excellent translation of my thesis’s summary I am also very thankful to my Vietnamese friends in Delft for a lot of joyful and relaxing activities, especially to my roommate Phan Hien Vu for his delicious meals and drinks The financial support by Vietnam Ministry of Education and Training, CICAT and Section of Structural Mechanics is gratefully acknowledged And last but not least, I would like to greatest gratitude to my parents and my sisters for their unconditional encouragement and support Le Luong Bao Nghi Delft, September 2015 List of relevant publication Article - letter to the editor Stroeven, P, Sluys, LJ, Le, LBN & He, H (2011) Porien in virtueel beton Cement: vakblad voor de betonwereld, 2011(4 |(juli)), 1-4 Le, LBN & Stroeven, P (2012) Strength and durability evaluation by DEM approach of green concrete based on gap-graded cement blending Advanced Materials Research, 450451, 631-640 Stroeven, P, Le, LBN & He, H (2012) Methodological approaches to 3D pore structure exploration in cementitious materials Key Engineering Materials, 517, 305-314 Stroeven, P, Le, LBN, Sluys, LJ & He, H (2012) Porosimetry by double-random multiple tree structuring in virtual concrete Image Analysis and Stereology, 31(1), 55-63 Stroeven, P, Le, LBN, Sluys, LJ & He, H (2012) Porosimetry by random node structuring in virtual concrete Image Analysis and Stereology, 31(2), 79-87 He, H, Le, LBN & Stroeven, P (2012) Particulate structure and microstructure evolution of concrete investigated by DEM Part 1: Aggregate and binder packing Heron, 57(2), 119-132 Le, LBN, Stroeven, M, Sluys, LJ & Stroeven, P (2013) A novel numerical multicomponent model for simulating hydration of cement Computational Materials Science, 78(October), 12-21 Le, LBN, He, H & Stroeven, P (2012) Particulate structure and microsstructure evolution of concrete investigated by DEM Part 2: Porosimetry in hydrating binders Heron, 57(2), 133-150 Li, K, Stroeven, P & Le, LBN (2015) Methodology for porosimetry in virtual cementitious composites to economically and reliably estimate permeability Image Analysis and Stereology, 34(2), 73-86 10 Stroeven, P, Li, K, Le, LBN, He, H & Stroeven, M (2015) Capabilities for property assessment on different levels of the micro-structure of DEM-simulated cementitious materials Construction and Building Materials, 88(July), 105-117 11 Le, LBN, Stroeven, P (2015) Effect of blending on properties of pore network structure in blended cements studied in virtual reality Cement and Concrete Composites (submitted) 158 References Article in volume – proceedings Stroeven, P, He, H & Le, LBN (2011) 2D and 3D routes to investigating pores in concrete In s.n (Ed.), 13th international congress for stereology (pp 1-4) Beijing: Tsinghua University Stroeven, P, Le, LBN & He, H (2011) 3D exploration of percolated porosity in virtual concrete In s.n (Ed.), 13th international congress for stereology (pp 1-4) Beijing: Tsinghua University Stroeven, P, Le, LBN, Stroeven, M & Sluys, LJ (2011) Discrete element modeling approach to porosimetry for durability risk estimation of concrete In E Onate & DRJ Owen (Eds.), Particles 2011 (pp 1-12) Barcelona: IACM Stroeven, P & Le, LBN (2011) Studying percolated porosity in concrete by dem In A-M El-Batahgy & M Waly (Eds.), Processing, performance and failure analysis of engineering materials (pp 447-456) Luxor, Egypt: IQCMEA-ICF Le, LBN & Stroeven, P (2012) Porosity of green concrete based on a gap-graded blend In AM Brandt, J Olek, MA Glinicke & CKY Leung (Eds.), Brittle matrix composites 10 (pp 315-324) Cambridge: Woodhead Publishing Stroeven, P, He, H & Le, LBN (2012) Analogue simulation by dem of material structure for property estimation of cementitious materials In s.n (Ed.), International US-Poland workshop multiscale computational modeling of cementitious materials (pp 155-164) Stroeven, P, Sluys, LJ & Le, LBN (2012) Assessment of pore characteristics in virtual concrete by path planning methodology In AM Brandt, J Olek, MA Glinicke & CKY Leung (Eds.), Brittle matrix composites 10 (pp 200-207) Cambridge: Woodhead Publishing Stroeven, P & Le, LBN (2013) Evaluation by discrete element method (DEM) of gapgraded packing potentialities for green concrete design In C Goodier, M Soutsos, TT Le & VT Nguyen (Eds.), International conference on sustainable built environment for now and the future (pp 347-354) Hanoi: National University of Civil Engineering Stroeven, P & Le, LBN (2013) Porosimetry by DraMuTS applied to DEM-produced cementitious materials In H Uzoegbo & W Schmidt (Eds.), International conference on advances in cement and concrete technology in Africa (pp 277-284) 10 Le, LBN & Stroeven, P (2014) Packing issue in cement blending for sustainability developments - Approach by discrete element method In V Bilek & Z Kersner (Eds.), Proceedings of the international conference on non-traditional cement and concrete, ICNTCC2014 Vol International Journal of Research in Engineering and Technology (online) (pp 147-150) Brno: NOVPRESS 11 Stroeven, P, He, H, Le, LBN & Li, K (2014) Modeling possibilities of concrete structure for durability purposes In NB Barabash (Ed.), Proceedings of the international seminar on modelling and optimization of composites (pp 60-63) Odessa: Astroprint Curriculum vitae October 17th, 1983 born in Da Lat, Vietnam, as Le Luong Bao Nghi Sep 2001 – Mar 2006 Bachelor in Civil Engineering, Ho Chi Minh University of Technology Sep 2006 – Dec 2008 Master of Science in Structural Engineering, Ho Chi Minh University of Technology Mar 2010 – Mar 2015 PhD candidate in the Computational Mechanics group at the Faculty of Civil Engineering and Geosciences, Delft University of Technology [...]... by new porosimetry techniques that are applicable to the virtual porous materials, evaluation of the permeability of the materials by an economical pore-scale network model and investigation of the influence of pore characteristics on mechanical and transport properties of cementitious materials A new material model for the simulation of hydration and microstructural evolution of cementitious materials. .. applications Microstructural simulation of hydrated cementitious materials (Chapter 2) Investigation of pore characteristics and permeability of cementitious materials (Chapter 5) Computational porosimetries on virtual porous media (Chapter 3) Implication of microstructure and pore characteristics on elastic properties and damage behaviours of cementitious materials (Chapter 6) Permeability estimation on virtual. .. saturation, flow path blocking by movement of loose particles under high pressure and swelling of the CSH gel due to re-saturation 1.3.2 Computational simulation of cementitious materials An overview of computational works on cementitious materials The fast and continuing advances of computing facilities nowadays promote doing research on virtual materials as a more economic and reliable option Several... investigate mechanical properties and fracture process of cement pastes at micro- scale [56-61] On the nano-scale, the focus is on modelling of the nanostructure of CSH gel and on its evolution during hydration of PC Several models [6,62-66] are proposed for description of CSH as colloid structure of jennite (CSH substance) and of the gel pores Modelling approaches The ‘vector approach’ and ‘discretization approach’... of pore characteristics on elasticity moduli and on tensile damage behaviour The differences in properties and damage evolution are investigated as a result of different pore size distributions, different porosities and pore structures in ITZ and bulk zone The effect of RHA blending is considered Finally, summaries, conclusions and recommendations are given in Chapter 7 Introduction 15 Introduction... in the microstructure of the cement paste The measurement of saturated permeability of cementitious materials is hampered by a time-dependent reduction of the flow rate because of the so-called ‘self-sealing effect’ (SSE) [18] This phenomenon is the consequence of changes in pore structure during the process due to dissolution and precipitation of ions along the flow paths, continuing hydration by water... (Chapter 4) Conclusion (Chapter 7) Figure 1.6 Flow chart of the thesis Chapter 2 Microstructural simulation of hydrated cementitious materials Since the microstructure of a hardened cementitious material continuously varies over a long period of time (i.e., couple of decades), performing experimental tests on specimens at different ages to record the microstructural developments is extremely time-consuming... been and are still being carried out to improve the performance as well as the economic aspects of the concrete material, at the same time meeting increasing environmental demands From the structural engineering point of view, concrete at macro -level is considered a continuous and homogeneous material, of which physical and mechanical features nonetheless originate from its underlying meso- and micro- structure... the solid particles at micro- level 1.2 Pore characteristics and porosimetries One of the most important challenges in concrete engineering and research is to acquire an understanding of the pore network structure and of its influence on the physical, mechanical and durability properties of concrete Indeed, the strength, elasticity properties and permeability are affected not only by the porosity but... Chapter 1 Introduction 1.1 Concrete as a particulate and porous material at different levels of its microstructure Though used in construction industry for centuries, concrete is still one of the most popular materials for buildings and infrastructures (Figure 1.1) The long-lasting use of concrete comes from advantages as to its economy, geometrical flexibility, high fire-resistance and durability, etc .. .Micro- level Porosimetry of Virtual Cementitious Materials Structural Impact on Mechanical and Durability Evolution Luong Bao Nghi Le Micro- level Porosimetry of Virtual Cementitious Materials. .. model and investigation of the influence of pore characteristics on mechanical and transport properties of cementitious materials A new material model for the simulation of hydration and microstructural... microstructural evolution of cementitious materials As afore-mentioned, the micro- numerical models for simulation hydration and microstructural evolution of cement are classified into the ‘discretization