@proceedings {332, title = {Creep of Bulk C-S-H: Insights from Molecular Dynamics Simulations}, journal = {10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete StructuresCONCREEP 10}, volume = {CONCREEP 10: MECHANICS AND PHYSICS OF CREEP, SHRINKAGE, AND DURABILITY OF CONCRETE AND CONCRETE STRUCTURES }, year = {2015}, month = {Sep-17-2015}, pages = {511-516}, publisher = {American Society of Civil Engineers}, address = {September 21{\textendash}23, 2015, Vienna, AustriaReston, VA}, abstract = {

Understanding the physical origin of creep in calcium\–silicate\–hydrate (C\–S\–H) is of primary importance, both for fundamental and practical interest. Here, we present a new method, based on molecular dynamics simulation, allowing us to simulate the long-term visco-elastic deformations of C\–S\–H. Under a given shear stress, C\–S\–H features a gradually increasing shear strain, which follows a logarithmic law. The computed creep modulus is found to be independent of the shear stress applied and is in excellent agreement with nanoindentation measurements, as extrapolated to zero porosity.

}, doi = {10.1061/978078447934610.1061/9780784479346.061}, author = {Mathieu Bauchy and Enrico Masoero and Franz-Josef Ulm and Roland Jean-Marc Pellenq}, editor = {Hellmich, Christian and Pichler, Bernhard and Kollegger, Johann} } @proceedings {333, title = {Creep of Clay: Numerical Results at the Scale of a Layer and Experimental Results at the Scale of Thin Self-Standing Films}, journal = {10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete StructuresCONCREEP 10}, volume = {CONCREEP 10: MECHANICS AND PHYSICS OF CREEP, SHRINKAGE, AND DURABILITY OF CONCRETE AND CONCRETE STRUCTURES }, year = {2015}, month = {Sep-17-2015}, pages = {531-536}, publisher = {American Society of Civil Engineers}, address = {September 21{\textendash}23, 2015, Vienna, AustriaReston, VA}, abstract = {

This work focuses on the creep of clay-based materials, which exhibit significant analogies with cement-based materials. Here, we studied the creep of clay at two scales and with two techniques: numerically (with molecular simulations) at the scale of a clay layer (nm), and experimentally at the scale of thin self-standing clay films (few dozen m). At the scale of the clay layer, numerical simulations showed that the shear rate was constant over time and an affine function of the shear stress. Creep experiments showed that, after a transient period, the creep function of our thin self-standing clay films was a logarithmic function of time. A comparison of the results obtained at the two scales shows that the origin of the logarithmic feature of clay creep must at least partly originate from a scale greater than that of an individual clay layer. By analogy, such result is likely to hold for cementitious materials, which are also known to creep logarithmically with respect to time in the long term: the origin of this logarithmic feature is likely to stem at least partly from a scale greater than the scale of an individual C-S-H layer.

}, doi = {10.1061/978078447934610.1061/9780784479346.064}, author = {Benoit Carrier and Matthieu Vandamme and Roland Jean-Marc Pellenq and Henri Van Damme}, editor = {Hellmich, Christian and Pichler, Bernhard and Kollegger, Johann} } @proceedings {331, title = {C-S-H across Length Scales: From Nano to Micron}, journal = {10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete StructuresCONCREEP 10}, volume = {CONCREEP 10: MECHANICS AND PHYSICS OF CREEP, SHRINKAGE, AND DURABILITY OF CONCRETE AND CONCRETE STRUCTURES }, year = {2015}, month = {Sep-17-2015}, pages = {39-48}, publisher = {American Society of Civil Engineers}, address = {September 21{\textendash}23, 2015, Vienna, AustriaReston, VA}, abstract = {

Despite their impact on longevity, serviceability, and environmental footprint of our built infrastructure, the chemo-physical origins of nanoscale properties of cementitious materials, and their link to macroscale properties still remain rather obscure. Here, we discuss a multi-scale approach that describes different aspects of physical properties of C-S-H at the nano- and meso-scales. These include dynamics of water, thermal properties and mechanical behavior of C-S-H and its effect on properties of cement paste at different scales.

}, doi = {10.1061/978078447934610.1061/9780784479346.006}, url = {http://ascelibrary.org/doi/book/10.1061/9780784479346http://ascelibrary.org/doi/pdf/10.1061/9780784479346http://ascelibrary.org/doi/10.1061/9780784479346.006http://ascelibrary.org/doi/pdf/10.1061/9780784479346.006}, author = {Mohammad Javad Abdolhosseini Qomi and Enrico Masoero and Mathieu Bauchy and Franz-Josef Ulm and Emanuela Del Gado and Roland Jean-Marc Pellenq}, editor = {Hellmich, Christian and Pichler, Bernhard and Kollegger, Johann} } @proceedings {335, title = {Hydration Kinetics and Gel Morphology of C-S-H}, journal = {10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete StructuresCONCREEP 10}, volume = {CONCREEP 10: MECHANICS AND PHYSICS OF CREEP, SHRINKAGE, AND DURABILITY OF CONCRETE AND CONCRETE STRUCTURES}, year = {2015}, month = {Sep-17-2015}, pages = {565-573}, publisher = {American Society of Civil Engineers}, address = {September 21{\textendash}23, 2015, Vienna, AustriaReston, VA}, abstract = {

Calcium-silicate hydrate (C-S-H) is the main binder in cement and concrete. It starts forming from the early stages of cement hydration and it progressively densifies as cement sets. C-S-H nanoscale building blocks form a cohesive gel, whose structure and mechanics are still poorly understood, in spite of its practical importance. Here we review a statistical physics approach recently developed, which allows us to investigate the C-S-H gel formation under the out-of-equilibrium conditions typical of cement hydration. Our approach is based on colloidal particles, precipitating in the pore solution and interacting with effective forces associated to the ionic environment. We present the evolution of the space filling of C-S-H with different particle interactions and compare them with experimental data at different lime concentrations. Moreover, we discuss the structural features of C-S-H in the mesoscale in terms of the scattering intensity. The comparison of our early stage C-S-H structures with small angle neutron scattering (SANS) experiments shows that long range spatial correlations and structural heterogeneties that develop in that early stages of hydration persist also in the hardened paste.

}, doi = {10.1061/978078447934610.1061/9780784479346.069}, author = {Katerina Ioannidou and Enrico Masoero and Pierre E. Levitz and Roland Jean-Marc Pellenq and Emanuela Del Gado}, editor = {Hellmich, Christian and Pichler, Bernhard and Kollegger, Johann} } @proceedings {334, title = {Kinetic Simulations of Cement Creep: Mechanisms from Shear Deformations of Glasses}, journal = {10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete StructuresCONCREEP 10}, volume = {CONCREEP 10: MECHANICS AND PHYSICS OF CREEP, SHRINKAGE, AND DURABILITY OF CONCRETE AND CONCRETE STRUCTURES}, year = {2015}, month = {Sep-17-2015}, pages = {555-564}, publisher = {American Society of Civil Engineers}, address = {September 21{\textendash}23, 2015, Vienna, AustriaReston, VA}, abstract = {

The logarithmic deviatoric creep of cement paste is a technical and scientific challenge. Transition State Theory (TST) indicates that some nanoscale mechanisms of shear deformation, associated with a specific kind of strain hardening, can explain the type of deviatoric creep observed experimentally in mature cement pastes. To test this possible explanation, we simulate the shear deformations of a colloidal model of cement hydrates at the nanoscale. Results from quasi-static simulations indicate a strain hardening analogous to that postulated by the TST approach. Additional results from oscillatory shear (fatigue) simulations show an increase of deformation with number of loading cycles that is consistent with the observed creep. These findings indicate that nanoscale simulations can improve our current understanding of the mechanisms underlying creep, with potential to go beyond the logarithmic creep and explore the onset of failure during tertiary creep.

}, doi = {10.1061/978078447934610.1061/9780784479346.068}, author = {Enrico Masoero and Mathieu Bauchy and Emanuela Del Gado and Hegoi Manzano and Roland Jean-Marc Pellenq and Franz-Josef Ulm and Sidney Yip}, editor = {Hellmich, Christian and Pichler, Bernhard and Kollegger, Johann} } @proceedings {330, title = {The Meso-Scale Texture of Cement Hydrate Gels: Out-of-Equilibrium Evolution and Thermodynamic Driving}, journal = {10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures CONCREEP 10}, volume = {CONCREEP 10: MECHANICS AND PHYSICS OF CREEP, SHRINKAGE, AND DURABILITY OF CONCRETE AND CONCRETE STRUCTURES}, year = {2015}, month = {Sep-17-2015}, pages = {34-38}, publisher = {American Society of Civil Engineers}, address = {September 21{\textendash}23, 2015 Vienna, AustriaReston, VA}, abstract = {

By the end of cement hydration calcium-silicate-hydrate (C-S-H) gels extends over tens and hundreds of nanometers. Their complex texture affects directly, and to a large extent, the macroscopic hygrothermal and mechanical behavior of cement. Here we review a statistical physics approach recently developed, which allows us to investigate the gel formation under the out-of-equilibrium conditions typical of cement hydration and the role of the nano-scale structure in C\—S\—H mechanics upon hardening. Our investigations have unveiled the role, in the C-S-H gels, of nano-scale structural and mechanical heterogeneities that develop due to the the far-from-equilibrium physico-chemical environment in which the material forms. A subtle interplay between the out-of-equilibrium evolution and the effective interactions emerging between the nano-scale units of the gels at different stages of the hydration process ultimately determines the mesoscale texture of cement hydrates and their material properties.

}, doi = {10.1061/978078447934610.1061/9780784479346.005}, author = {Emanuela Del Gado and Katerina Ioannidou and Enrico Masoero and Roland Jean-Marc Pellenq and Franz-Josef Ulm and Sidney Yip}, editor = {Hellmich, Christian and Pichler, Bernhard and Kollegger, Johann} } @proceedings {329, title = {Shrinkage Due to Colloidal Force Interactions}, journal = {10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures CONCREEP 10}, volume = {CONCREEP 10: MECHANICS AND PHYSICS OF CREEP, SHRINKAGE, AND DURABILITY OF CONCRETE AND CONCRETE STRUCTURES}, year = {2015}, month = {Sep-17-2015}, pages = {13-16}, publisher = {American Society of Civil Engineers}, address = {September 21{\textendash}23, 2015, Vienna, AustriaReston, VA }, abstract = {

It has long been argued that shrinkage in cementitious materials can occur even in the absence of drying phenomena. Herein we argue that such shrinkage is attributable to colloidal forces that develop between C-S-H particles during the hydration in an out-of-equilibrium process. We base our argument on meso-scale simulation results, and show via microporomechanics theory that such colloidal forces can lead to the build-up of solid eigenstresses causing macroscopic shrinkage deformation.

}, doi = {10.1061/978078447934610.1061/9780784479346.002}, author = {Franz-Josef Ulm and Roland Jean-Marc Pellenq}, editor = {Hellmich, Christian and Pichler, Bernhard and Kollegger, Johann} }