Increased Heat-Resistant Concrete with Polypropylene Fibres Testing Methods in set and unset Concrete

The consequences of fires in tunnels in Austria and other countries resulted in seeking for more information on the effects of fires in tunnels on the concrete structure. The findings from different research programs led to a new guideline of the Austrian Society for Concrete, and Construction Technology (OVBB). By adding polypropylene fibres a spalling of concrete of the inner lining can be avoided successfully in tunnels even under the extreme condition of fires. An equal distribution of fibres in the concrete is essential for their effectiveness. To verify the distribution of fibres during construction, testing methods which are explained in the article at hand were developed. In addition, the conclusions derived from the practical use at a construction site are shown.