Punching Shear Behavior of Continuous Bubbled Reinforced Reactive Powder Concrete Slab


This paper presents an experimental investigation on punching shear behavior of continuous bubbled reinforced Reactive Powder Concrete (RPC) slabs. Bubbled slab is one of the various types of voided slabs. It consists of bubbles placed inside a concrete slab which will reduce the self-weight of the structure by about 35% (Tina Lai 2009). On the other hand, using RPC make it possible for structural member to have smaller dimensions due to the great strength of this type of concrete. In this study, these two method to increase the building spaces dimensions by reducing self-weigh of the structure by using bubbled slabs and to decrease the structural members' dimensions by using RPC have been investigated together.To study the punching shear behavior of continuous bubbled flat slabs such as the ultimate load carrying capacity, central deflection and slabs crack pattern at the ultimate load, nine different types of slabs were tested. The parameters of the study were type of concrete (RPC and Normal Concrete (NC)), bubbles diameter to slab thickness ratio (D/t) of (0.6 and 0.7), bubbles location (at all slab area, started from distance D and 1.5D from the center slab) and solid slab. The test results show that the crack pattern and ultimate load capacity as well as maximum deflection depends on all of the mentioned parameters, were by increasing (D/t) ratio the ultimate load capacity increases about (6.49 and 9.58%) for slabs with bubbles started at distance 2D and 3D, respectively. But in the slabs with bubbles at all slab area the ultimate load and the maximum deflection decreases about (6.63 and 9.47%) and (7.96 and 6.84%) for RPC and NC slabs, respectively. Also, the solid slab increases the ultimate load about (5.28%) compare to bubbled slab at all area.It was found that by removing bubbles from center of the slab at distance 2D and 3D the ultimate load will increase about (14.72 and 8.76%), respectively for slabs with (D/t = 0.6) compare to slabs with bubbles at all slab area, and for slabs with (D/t = 0.7) the ultimate load will increase about (30.85 and 27.65%), for bubbles at distance 2D and 3D, respectively.Using the NC decreases the ultimate load compare to RPC by about (52.82-54.25%) for different (D/t) ratio.