Nano-scale mechanics of colloidal C-S-H gels

Gels of calcium-silicate-hydrates (C-S-H) are the glue that is largely responsible for the mechanical properties of cement. Despite their practical relevance, their nano-scale structure and mechanics are still mainly unexplored, because of the difficulties in characterizing them in a complex material like cement. We propose a colloidal model to investigate the gel mechanics emerging in the critical range of length-scales from several tens to hundreds of nanometers. We show that the size polydispersity of the hydrates and size-dependent effective interactions can explain the mechanical heterogeneities detected in nano-indentation experiments. We also show how these features control the arising of irreversible structural rearrangements under deformation, which are good candidates as nano-scale mechanisms underlying mechanical aging and slow structural relaxation in the gels

Surface Chemistry and Atomic-Scale Reconstruction of Kerogen-Silica Composites

The interest in gas shale, a novel source rock of natural gas, has tremendously increased in recent years. Better understanding of the kerogen/rock interaction is of crucial importance for efficient gas extraction and hence for asset management. In this study, we explore the possible chemical bonds between kerogen and silica, one of the most predominant mineral constituents of gas shale by means of quantum chemistry. Energetically favorable bond formation reactions are found between alcoholic hy-droxyl, carboxylate and aldehyde groups as well as aliphatic double bonds of kerogen and the silica surface. The performance of a reactive force field is also assessed in a representative set of chemical reactions, which was found satisfactory. The potential impact of bond formation reactions between the two phases on the actual kerogen-silica interface are discussed in function of the kerogen type, maturity and density. Finally, a methodology aiming to reconstruct realistic kerogen-silica interfaces is presented

AI and model management: FAW research in environmental information systems

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Management von nicht-explizitem Wissen: Noch mehr von der Natur lernen. T. 3: Die Sicht verschiedener akademischer Faecher zum Thema des nicht-expliziten Wissens Abschlussbericht

Available from TIB Hannover: F01B1459 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

Management von nicht-explizitem Wissen: Noch mehr von der Natur lernen. T. 1: Ergebnis und Einordnung - FAW-Methodologie des Wissensmanagements und Anwendungen, Zusammenfassungen der Beitraege anderer Projektpartner und Vorschlag fuer ein Forschungsprogramm Abschlussbericht

Available from TIB Hannover: F01B1457 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

The FAW preference elicitation tool

SIGLETIB Hannover: RO 9283(90006) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman