Punching shear behavior of rubberized concrete slab

Punching shear of flat slabs made from normal concrete is a local, brittle failure that may occur before the ductile flexural failure. Since the concrete technology introduced alternative materials into concrete to promote the sustainability by using recycle material such as agriculture waste and industrial by product, the quality of this concrete need to be investigate further in all aspect. Therefore, this study is initiated to investigate the performance of concrete containing rubber to be used as structural element. This study is investigated the behavior of rubberized concrete flat slab subjected to the punching load. The effect of rubberized concrete and different slab thickness to the punching shear strength is main consideration in this investigation. The study is started by evaluating the mechanical properties of rubberized concrete such as compressive strength, flexural strength and splitting tensile strength. In comparison to normal concrete, the mechanical properties of rubberized concrete shown a reduction in compressive strength and increase in flexural strengths and split tensile strength. The performance of rubberized flat slab is observed in term of punching shear strength, critical perimeter and displacement by using experimental approach. Punching shear strength and development of crack within critical perimeter are observed during experimental test. Punching shear strength produced by experiment test is compared to values obtained by established equations from EC2 and ACI 813. From this comparison, it is indicated that the equations are over predicted the punching shear strength in the range of 12 – 72 %. Rubberized concrete slab exhibited ductile failure and underwent significant displacement before reaching punching fracture. Critical perimeter produced by rubberized concrete slab also extended more than produced in the normal concrete in the range of 34 - 75%. The punching shear strength of rubberized concrete slab also exhibited a significant reduction in punching shear resistance compared to normal concrete for the similar slab thickness. As conclusion, the rubberized concrete produced better critical perimeter at the lower punching shear resistance.