2006 | OriginalPaper | Buchkapitel
Micromechanical Observation of Fracture Process in Mortars
verfasst von : E. Schlangen, O. Copuroglu
Erschienen in: Fracture of Nano and Engineering Materials and Structures
Verlag: Springer Netherlands
Aktivieren Sie unsere intelligente Suche, um passende Fachinhalte oder Patente zu finden.
Wählen Sie Textabschnitte aus um mit Künstlicher Intelligenz passenden Patente zu finden. powered by
Markieren Sie Textabschnitte, um KI-gestützt weitere passende Inhalte zu finden. powered by
Cement-based materials like concrete and mortars are quasi-brittle materials. These materials show a softening behaviour when tested in uni-axial tension. An example of such a behaviour is shown in Fig. 1, which is a result obtained from a tensile test on mortar in the special micro-tensile testing machine explained in this paper. The shape of the curve and the area under the curve which is a measure for the fracture energy, is strongly related to the heterogeneity of the material, see for instance Schlangen and van Mier [
1
]. At the weak spots in the material (generally the interface at grain boundaries) first micro-cracks develop in the material when a load is applied. Subsequent loading will result in a localized crack that will propagate through the material. This mechanism is believed to take place in all cement based materials, but is hard to observe. Stable fracture in a tensile test can only be realised with a closed loop hydraulic testing machine. Observations of micro-cracking and localization of these cracks is a difficult task. However to be able to improve materials a complete understanding of the fracture process is necessary. Furthermore durability is a hot issue in cement based materials. Ingress of water and ions result in internal reactions of concrete and embedded steel reinforcement which can result in fast degradation of concrete structures [
2
]. Understanding the fracture process, the way micro-cracks and localized cracks propagate through the material, is thus important in order to control transport through the material and design the material in such a way that a long service life of structures is guaranteed.