Reinforcement of A Cementitious Matrix by Long or Continuous Fibers

2. Mai 2007

Im Rahmen der SFB-Seminare wird Dr. Bruno FIORIO am 15. Mai um 13 Uhr im BEY67 einen Vortrag mit dem Titel „Reinforcement of A Cementitious Matrix by Long or Continuous Fibers: Mechanical Behaviour of the Composite and Interfacial Bond Behaviour“ halten. Dr. Fiori ist Senior Lecturer an der University of Cergy-Pontoise, France im Laboratoire de mécanique et matériaux du Génie Civil (Mechanics and construction materials laboratory).

Aus dem Abstract:

The first part of the presentation will give the results of an experimental parametric study performed on 7x7x28 cm mortar specimens reinforced with different types of long fibres: grids of carbon fibres reinforced polymer (epoxy, PVC, latex, acrylic, silica doped acrylic) and continuous glass or carbon yarns. The results obtained will be discussed in term of ultimate strength, strain, crack propagation and ductility. They show how the properties of the fibre / matrix interface influence the level of ultimate load and ductility of the reinforced mortar, and how the strength and the ductility are linked in the case of fibrous reinforcements.

The second part of the presentation will introduced the results of pull out tests performed to complements the flexural tests in the case of yarns reinforced mortar. The results obtained will be given for two layouts of the yarn: straight yarn and curved yarn. This study has shown the effect of the yarn impregnation by the mortar matrix, of the structure and of the conformation of the yarn on the mechanical behaviour of the interface.

Based on the observations made during these tests (most of them were direct visual observations), a phenomenological model build to explain the results will then be presented. The model considers the resulting load on the yarn as the sum of three contributions:

  • tension in the peripherical filaments which is governed by the free length of these filaments between two anchorage points in the mortar matrix,
  • tension in the core filaments which is governed by their interaction with the mortar matrix in the curved parts of the yarn,
  • friction of the broken filaments on there counterparts.

The confrontation of the model with the experimental results finally show that the above three phenomena are mainly responsible for the observed mechanical behaviour.

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