Controlling cracking to acceptable levels in concrete structures requires accurate detailing and good construction practices. This is more prevalent in ground supported slabs that are typically detailed to avoid cracks occurring under service stresses. Detailing the slab to avoid these cracks puts a number of limitations on the floor design and construction. There is an upper limit on panel size and shape, restraint should be limited as much as possible and of course joints are required, which can be expensive and may require on-going maintenance. And even with all this effort, cracks can still occur, and when they do they tend to be large and can have an adverse effect on the serviceability of the floor.
Recent Standards from Europe(5,6,7) enable the engineer to design using steel fibre reinforced concrete (SFRC) combined with conventional reinforcing. For floor slabs this means any panel size or shape can be considered, even when the floor is fully restrained, and importantly these solutions can be joint free. Using combined reinforcing also enables the design of economical liquid retaining structures, such as containment bunds, dangerous goods store floors, tank base slabs, watertight basement slabs.
This paper discusses the theory behind this design approach and provides a number of local and overseas project examples.
