STEEL FIBRE REINFORCED CONCRETE

Steel Fibre Reinforced Concrete (SFRC) Floor Slabs

Conventional practice usually concentrates welded wire fabric reinforcement within a single plane of a floor slab. Often mesh is in the wrong place. Fabric does very little to reinforce the outer zones, which is why spalling is common at the joints and edges. The primary function of welded wire fabric is to hold the floor slab together after the first small hairline cracks have propagated to larger fractures. This serves to maintain some degree of “structural integrity”.

Conventional wisdom’s approach to floor slabs is to maintain “material integrity” through SFRC mix designs. This integrity is accomplished by:

• Increasing the initial first crack strength.
• Large numbers of fibres intercepting the micro-cracks and preventing propagation by controlling tensile strength.
• Unlike rebar and welded wire fabric, fibres are dispersed throughout the slab to reinforce isotropically, so there is no weak plane for a crack to follow.
• Increases in flexural strength can make it possible to use a thinner slab and eliminate the cumbersome welded wire fabric.
• Whether it is for lighter duty commercial service or for heavy manufacturing, SFRC slabs are capable of withstanding any load. The only variable is the addition rate of fibre, which could be as low as 20kg/m3 and as high as 100 kg/m3.