A high performance fibre concrete with a cylinder strength of about 80 MPa was developed and tested both under laboratory and site conditions. The post-cracking properties were determined in a series of three-point notched beam tests according to EN 14651. Subsequently, double punch tests on 150 mm cubes were carried out to verify whether such tests could be used for control of the properties of the concrete cast at site. It was shown that the same relations can be obtained by using simple conversion factors. Additionally, it was studied if it is possible to test round panels according to ASTM C1550-02 to verify the properties of the fibre concrete. Also here, it turned out that it is possible to derive simple conversion factors to relate the results of the round panel tests to those of the notched beam tests. The findings provide useful information for a practical quality assessment with regard to the execution of fibre reinforced concrete structures.@en

An investigation is carried out into the applicability of self-compacting high-performance fiber concrete (HPFC) in foundations. A concrete mixture has been designed with a concrete cube strength of about 110 MPa. The concrete contains 60 kg/m³ steel fibers. The properties of the HPFC developed are very suitable for structural applications, especially because the post-cracking tensile strength, provided by the fibers, is higher than the axial tensile strength of the concrete so that hardening in tension occurs after crack formation, often characterized by multiple cracking. This not only results in a high bearing capacity but as well in substantial durability. As a potential application foundation elements are considered. Experiments have been carried out to determine the pre- and post-cracking strength properties, the shear resistance of short beams with loads near to the supports, the anchorage length of reinforcing bars, and the shear capacity of pile caps. The results of the tests are used for verification of the applicability of the general design rules for fiber concrete, as found in the fib Model Code 2010, to the HPFC developed. The HPFC developed is characterized by high strength and ductility, is durable and self-compacting. The research program showed that the design of structures with the HPFC considered can be based on existing design rules with some extensions.

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An investigation was executed into the applicability of self-compacting high performance fiber concrete in foundations. The applied concrete has a concrete cube strength of about 110 MPa and contains 60 kg/m³ hooked-end steel fibers (L_F = 30 mm, D_F = 0.38 mm). This publication consists of two parts: (1) Experimental assessment and verification of design rules and (2) assessment of fiber orientation and distribution. In the first part, experiments are described which were carried out to determine the pre- and post-cracking strength properties, the shear resistance of short beams, the anchorage length of rebars, and the shear capacity of foundation slabs supported on piles. The test results were used for a verification and extension of design rules for fiber reinforced concrete (FRC) found in the fib Model Code 2010. The application of the FRC developed can lead to substantial savings in concrete and reinforcing steel. In the present second part, cross-sections of two slabs and a beam of this testing series have been analyzed with regard to fiber orientation and distribution. An image analysis, executed on 111 concrete areas, indicates that a preferred fiber orientation could not be identified throughout the assessed elements. The data supports the conclusion of a good fiber distribution as well; a strong correlation was obtained for the data set of full images between measured and theoretical relation of fiber orientation and fiber density.@en