Mesoscopic packing of disk-like building blocks in calcium silicate hydrate

At 100-nanometer length scale, the mesoscopic structure of calcium silicate hydrate (C-S-H) plays a critical role in determining the macroscopic material properties, such as porosity. In order to explore the mesoscopic structure of C-S-H, we employ two effective techniques, nanoindentation test and molecular dynamics simulation. Grid nanoindentation tests find different porosity of C-S-H in cement paste specimens prepared at varied water-to-cement (w/c) ratios. The w/c-ratio-induced porosity difference can be ascribed to the aspect ratio (diameter-to-thickness ratio) of disk-like C-S-H building blocks. The molecular dynamics simulation, with a mesoscopic C-S-H model, reveals 3 typical packing patterns and relates the packing density to the aspect ratio. Illustrated with disk-like C-S-H building blocks, this study provides a description of C-S-H structures in complement to spherical-particle C-S-H models at the sub-micron scale.

[1]  François Toutlemonde,et al.  The nano-mechanical signature of Ultra High Performance Concrete by statistical nanoindentation techniques , 2008 .

[2]  H. Jennings,et al.  A model for two types of calcium silicate hydrate in the microstructure of Portland cement pastes , 2000 .

[3]  P. Monteiro,et al.  Nanostructure of calcium silicate hydrates in cements. , 2010, Physical review letters.

[4]  I. Richardson.  The calcium silicate hydrates , 2008 .

[5]  Cement modeled as poly-dispersed assemblage of disk-like building blocks , 2015 .

[6]  A. Misra,et al.  Nature of Interatomic Bonding in Controlling the Mechanical Properties of Calcium Silicate Hydrates , 2016 .

[7]  Kevin Paine,et al.  A comprehensive review of the models on the nanostructure of calcium silicate hydrates , 2015 .

[8]  S. H. Chen,et al.  Multiscale structure of calcium- and magnesium-silicate-hydrate gels , 2014 .

[9]  O. Büyüköztürk,et al.  Mechanical behavior of a composite interface: Calcium-silicate-hydrates , 2015 .

[10]  J. Andrade,et al.  A nanoscale numerical model of calcium silicate hydrate , 2011 .

[11]  Surendra P. Shah,et al.  Modeling the linear elastic properties of Portland cement paste , 2005 .

[12]  J. Dolado,et al.  Recent advances in modeling for cementitious materials , 2011 .

[13]  F. Ulm,et al.  Nanostructure and nanomechanics of cement: polydisperse colloidal packing. , 2012, Physical review letters.

[14]  G. Seifert,et al.  Do Cement Nanotubes exist? , 2012, Advanced materials.

[15]  Franz-Josef Ulm,et al.  Nanogranular packing of C–S–H at substochiometric conditions , 2010 .

[16]  Jeffrey J. Thomas,et al.  Composition and density of nanoscale calcium-silicate-hydrate in cement. , 2007, Nature materials.

[17]  O. Buyukozturk,et al.  Mesoscale modeling of cement matrix using the concept of building block , 2015 .

[18]  Seung-Jun Kwon,et al.  Effect of W/C Ratio on Durability and Porosity in Cement Mortar with Constant Cement Amount , 2014 .

[19]  Markus J Buehler,et al.  A realistic molecular model of cement hydrates , 2009, Proceedings of the National Academy of Sciences.

[20]  S. Brunauer,et al.  THE SURFACE ENERGY OF TOBERMORITE , 1959 .

[21]  Stephen Brunauer.  Surface energy of a calcium silicate hydrate , 1977 .

[22]  M. Griebel,et al.  The nano-branched structure of cementitious calcium–silicate–hydrate gel , 2011 .

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

[24]  Gilles Chanvillard,et al.  Modelling Elasticity of a Hydrating Cement Paste , 2007 .

[25]  A. Whittle,et al.  Mesoscale properties of clay aggregates from potential of mean force representation of interactions between nanoplatelets , 2014 .

[26]  Kenneth C. Hover,et al.  Mercury porosimetry of hardened cement pastes , 1999 .

[27]  Florence Sanchez,et al.  Nanotechnology in concrete – A review , 2010 .

[28]  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 .

[29]  Sidney Yip,et al.  Multiscale materials modelling at the mesoscale. , 2013, Nature materials.

[30]  I. Richardson.  Model structures for C-(A)-S-H(I) , 2014, Acta crystallographica Section B, Structural science, crystal engineering and materials.

[31]  Jeffrey J. Thomas,et al.  A multi-technique investigation of the nanoporosity of cement paste , 2007 .

[32]  B. Berne.  Modification of the overlap potential to mimic a linear site-site potential , 1981 .

[33]  M. Buehler,et al.  Roadmap across the mesoscale for durable and sustainable cement paste – A bioinspired approach , 2016 .

[34]  Franz-Josef Ulm,et al.  Statistical indentation techniques for hydrated nanocomposites: concrete, bone, and shale , 2007 .

[35]  H. Manzano,et al.  Shear deformations in calcium silicate hydrates , 2013 .

[36]  Zechuan Yu,et al.  Nano- and mesoscale modeling of cement matrix , 2014, Nanoscale Research Letters.

[37]  J. M. Chimenos,et al.  Elastic modulus of a chemically bonded phosphate ceramic formulated with low-grade magnesium oxide determined by Nanoindentation , 2015 .

[38]  S. H. A. Chen,et al.  Microstructure Determination of Calcium-Silicate-Hydrate Globules by Small-Angle Neutron Scattering , 2012 .

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

[40]  Stefano Merlino,et al.  The Crystal Structure of Tobermorite 14 Å (Plombierite), a C–S–H Phase , 2005 .

[41]  Christian Hellmich,et al.  Spherical and acicular representation of hydrates in a micromechanical model for cement paste: prediction of early-age elasticity and strength , 2009 .

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