Strengthening of Recycled Concrete Aggregates Two-Way RC Slabs by Externally Bonded CFRP

Abstract

The use of recycled concrete technology has become an international urgent demand owing to the rapid growth of construction industry along with the deteriorating ecological environment situation worldwide. Promotion of use of recycled concrete, can not only effectively reduce construction waste pollution to the natural environment, but also can reduce mining of the natural aggregate, which contributes to the sustainable development. Numerous investigations have been conducted on the use of recycled aggregate in concrete structures for more than a decade, and the relevant laboratory testing and field investigation results have showed that concrete structures built with recycled aggregates had good bearing capacity, deformation ability and earthquake resistant energy dissipation capacity. However, not that much attention has been paid in investigating the behavior of reinforced concrete two-way slabs cast with recycled concrete aggregates. This paper presents the results of a detailed experimental investigation conducted to study the behavior of the reinforced concrete two-way slab cast with recycled aggregates. Eight reinforced concrete two-way slabs with confined columns attached at the center of the slabs were cast using both natural and recycled aggregates. Two slabs each, cast with natural and recycled aggregates, served as control for respective types. Remaining four, two each from natural and recycled aggregates, were strengthened with carbon fiber reinforced polymer (CFRP) strips. Based on the experimental study, it was found that strengthening of two-way slabs containing natural and recycled aggregates was effective and capacities of the slabs increased by 37% and 35% respectively. Punching capacities of the slabs were also predicted by using the expressions available in literature and were compared with the experimentally observed capacities. Predicted values were found to be in close agreement with the experimentally observed values.