A look inside – computer tomography enables orientation analysis of steel fibers in reinforced concrete
Fraunhofer Institute for Industrial Mathematics and Institute of concrete structures and structural engineering at TU Kaiserslautern team up as one of three nominees in the category "Research" in this year's Bauma Innovation Award competition.
The increased use of steel fiber concrete offers great potentials in terms of time-savings and cost-efficiencies, in addition to being an environmentally friendly construction method. Some typical applications are composite slabs, load-bearing floors and walls, industrial floors, steel fiber reinforced shotcrete, segments for tunnel construction, and underwater slabs. A production method of uniform steel fiber reinforced concrete under building site conditions has remained a mystery. Established testing methods (wash-out, electro-magnetic, and photo-optic systems) provide information at great expense about the volume fraction of fiber. However, none of these have offered a reliable and verifiable analysis of the fiber distribution and direction.
Help has now arrived in the form of the algorithms developed at Fraunhofer ITWM, which form the basis of MAVI software. The engineers have succeeded in implementing the world's first descriptive testing of the fibers according to their positioning in space, projected length, and diameter. This news has been greeted with great national and international interest. The Institute of concrete structures and structural engineering at TU Kaiserslautern has implemented this new development for scientific testing of norms and for the study of the post-cracking behaviour of SFRC. The testing method is now ready for use in the assessment of damage claims and quality monitoring. An example is provided by tunnel construction where steel fiber reinforced tunnel segments have been economically used after the fibers' preferential direction was verified absolutely as being parallel to the border of the formwork.
Currently, the focus of effort is on fiber tomographics in stress cracks with the aim of acquiring an improved understanding of load bearing capabilities. The safe application of steel fiber reinforced concrete offers many new perspectives to the entire building industry.