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I. Merta:
"Hemp Fibre Reinforced Foam Concrete: Discussion of the Wedge Splitting Test Method";
International Journal of Research in Engineering and Technology, 0X (2014), S. 1 - 5.

In this research the fracture energy of foam concrete reinforced with fibres of hemp (Canabis Sativa L) has been experimentally evaluated with the employment of the Wedge Splitting Test (WST). As a matrix foam concrete of the specific weight 300 kg/m3 has been used with a mean compressive strength of 0.28 N/mm2. Hemp fibres of 5, 10, 20 and 40 mm in length with two different dosages per volume: 0.5 and 1% have been mixed in the matrix. The fracture energy, notch tensile strength and the compression strength has been determined for the resulting total of eight different foam concrete mixtures.
The results show that with the addition of fibres both the fracture energy and notch tensile strength of plain foam concrete could be enhanced up to 10 times. A generally increasing trend of both notch tensile strength and fracture energy with increasing fibres´ length and dosage has been observed. However, the tests showed also that nearly 50 % of specimens do not exhibited proper crack propagation during the WST with crack openings in the direction of the acting splitting force, but the crack propagated rather horizontally or under a distinctly inclined angle. The increase in the fibre´s dosage and/or length influenced the effectiveness of the test method even more negatively. It is believed that in the case of porous lightweight cementitious materials reinforced with a relatively high volumetric percentage of micro fibres, in order to obtain appropriate load-CMOD curves during the test, there is a need of modification either of the WST setup or the geometry of the specimens. The width of the specimens should be determined based on detailed investigations involving all influence parameters, like matrix composition, fibre type, geometry and dosage. However, the specimen´s should be wider than 150 mm defined in the norm.