IIBCC 2010, Aarlborg
Dr. Ulrich Mörschel, Erich Ingelsberger
Textechno Herbert Stein GmbH & Co. KG,
Mönchengladbach/Germany
ABSTRACT
Fibres for cement reinforcement generally are added in short-cut form of e.g. 6 mm length. To control the quality of the reinforced cement in an early stage, the tensile properties of the fibres need to be monitored. Because the testing of short-cut fibres is highly difficult, as a common practice fibre producers provide a segment of uncut tow for testing purposes. This practice bears the risk of mix-up and does not consider damage due to fibre stress during cutting. This paper introduces a new approach using a single-fibre tensile tester equipped with specially designed clamps, which open a window for precise determination of the tensile properties of even short-cut fibres. In addition, a special software algorithm allows to compensate the inherent error in elongation measurement, resulting in correct modulus and breaking elongation determination. In case of uncut long filaments the instrument can not only test the tensile properties, but also the linear density according to the well-proved vibroscopic principle. Since the linear density is related to the effective crosssection of the fibre, breaking tensions (e.g. in MPa) can be directly determined with this instrument, too. In the standard version as well as in the automated version the discussed tester it is already widely used by leading producers of PVA and PP fibres world-wide. Finally, for further tests on the uncut filament, the instrument can be equipped with wrap-bollard clamps to measure even coarse and highest-tenacity fibres, and with a special device to measure the friction along an individual fibre, which makes the instrument outstandingly suitable for tests on PVA reinforcement fibres
