PUNCHING SHEAR STRENGTH OF CONCRETE SLABS REINFORCED WITH RECYCLED STEEL FIBRES FROM WASTE TIRES

The increasing amount of waste tires around the world and their landfilling present a continuous problem to be solved. Currently, in some countries and unions of countries there are directives that prohibit landfilling and imply that constituent materials of waste tires must be recycled. The main goal of the presented research was to test the ability of sorted recycled tire steel fibres to perform in the same way as industrial steel fibres in flat slabs loaded in punching. Research included investigation of behavior of reinforced concrete slabs made of several mixes including plain concrete, mix with industrial steel fibres and mix with industrial and recycled steel fibres - hybrid fibres. Nine small-scale flat slabs were tested and results indicate that the use of hybrid fibres can improve the punching shear strength and deformation capacity of concrete slabs. Furthermore, slabs reinforced with hybrid fibres showed better behavior when compared to slabs reinforced only with industrial steel fibres.