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4Shear Characteristics of Fibre-Concrete

Concrete is a composite material consisting of water, cement and filler. To improve some mechanical characteristics, we added some substances, ingredients or dispersed reinforcement in our experiments. Dispersed reinforcement with sufficiently high tensile strength and modulus of elasticity may contribute to upgrade some concrete properties. The biggest benefit of adding dispersed reinforcement is in its positive influence on fracture energy and ductility. Many of our three-point and four point bending experiments confirmed this fact. It should be noticed that bending tests lead to cracking of concrete specimen. It is necessary to investigate their performance under different types of strain. We intended to create experiments in which the conditions of pure shear were realized without accompanying other stress components. In this context, it should be noted that in many real applications fibre-concrete is designed to the carry effects of shear forces. Unfortunately, no results of the realized experiments investigated the performance of fibre-concrete in pure shear mode without any accompanying bending effects. The realization of these specific conditions is not possible in the case of a prism beam with vertical transverse load. From this reason, we proposed an uncommon arrangement of the experiment: large-scale tubes to which a pure torsion load is applied. During the experiments, we measured the ultimate shear strength and the descending post-peak curve of transmitted stress. These results enable to derive the stress–strain dependence in the whole range of the stress-strain diagram in pure shear mode. The experiment with this new arrangement provides results of great importance and the benefit is far reaching.

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