A master's thesis by researcher Ali Tuaima Mihrab was defended at the University of Basrah’s College of Engineering (Department of Civil Engineering), under the supervision of Professor Dr. Abdul-Amir Atta-Allah Karim. The thesis is titled: Shear Strength of Corbels made of Reactive Powder Concrete Incorporating Recycled Aggerate
This study investigates the structural behavior of corbels made with Reactive Powder Concrete (RPC),involving the use of recycled concrete aggregate  by testing twelve full-scale double corbels with varying steel fiber ratio of (0%, 1% and 2%) and different recycled concrete replacement ratio of (0%, 10%, 20% and 30%) using two reactive powder concrete matrices, traditional RPC and modified RPC(MRPC). A curing regime of +60°C hot water for 72 hours followed by ambient temperature water to 28 days. The recycled aggregate lowered the compressive strength (Fcu) by roughly 10% at 30% replacement, leaving every mix within the ultra-high-performance range. Fibers slightly changed the compressive strength but transformed the tensile response. Shear capacity increased with fibers and fell with replacement. All the corbels failure modes were ductile and no sample failed due to brittle diagonal tension. The output revealed that the horizontal closed-stirrup details guaranteed this ductile failure mode rather than the fibers. The measured capacities of the corbels were compared to four analytical methods to find out which was better predict the corbels capacity. The shear-friction method and strut-and-tie method defined in ACI 318-19 provide conservative results. The Fattuhi model'sshowed the closest agreement with experimental results since it directly considers the fiber pull-out effect. In contrast, the only model that produced unconservative estimates was the Russo model. The findings provide an obvious design direction. RPC and MRPC corbels can contain up to 30% recycled aggregate, while still achieving an ultra-high-performance level, a comparable load capacity, and a ductile warning-type failure, provided at least 1% hooked-end fibers and the closed-stirrup details are used. MRPC requires less binder and superplasticizer to achieve this performance. Consequently, this material has both structural and environmental advantages since it allows demolition rubble to be reused in load-critical structural elements.