Punching Shear Behaviour and Repair Efficiency of Reinforced Eco-friendly Lightweight Concrete Slabs

In this study, the behaviour of eco-friendly concrete (Eco-Con) reinforced slabs was investigated by testing the structural behaviour of two-way slabs under punching shear, and by testing the performance of Eco-Con when used as a simulated repair material for one-way slabs under 4-point bending. Four Eco-Con mixes with the same target compressive strength of 32 MPa were used. The mixes consisted of one Portland cement concrete (CC) as the control mix, and three Eco-Con mixes namely: geopolymer rubber (GR), geopolymer lightweight expanded clay aggregate "LECA" (GL), and rubber engineered cementitious composite (RECC). The results for slabs sub-jected to punching shear showed 32 %, and 37 % less strength and 9 %, and 23 % less deflection when using Eco-Con concrete mixes GR and GL, respectively compared with the CC mix. The strength of Eco-Con RECC slab slightly decreased by 7 %, but its deflection capacity increased by 20 %, compared with the CC slab. The bending tests of 'repaired' slabs showed comparable slab bending strength capacity and ultimate deflection with the CC slab when using GR or GL mixes as the slab repair material. However, using RECC showed an increase in the slab bending strength capacity by 14 % and doubled the ultimate deflection, compared with the CC mix.