Punching of Concrete Slabs Reinforced by Recycling Waste

This study aims to experimentally evaluate the mechanical properties of concrete slabs reinforced with two types of fibers: metallic fibers (MF) and grids based on polypropylene fibers (PPG). The metallic fibers, sourced from machining waste of steel parts, are randomly distributed in the concrete, while the polypropylene fibers are arranged in grids. The investigation includes punching tests conducted on slabs measuring [25x50x7] cm³, as well as compression tests on cylinders with a diameter of Ø16 cm and a height of H32 cm. Mechanical resistance and tearing characteristics of the fibers were also assessed. The concrete’s composition was determined using the experimental “Dreux-Gorisse” method. Five different metal fiber contents (MF) were studied (W=0.2%, W=0.4%, W=0.6%, W=0.8%, and W=1%), alongside a control concrete sample (BT) with no fibers (W=0%) having the same composition as the matrix. Two variants of grids based on small-mesh polypropylene fibers (PPG/SM) and large-mesh (PPG/LM) configurations were considered. The comparative analysis of the results highlights that, at a fiber content of W=0.8%, metallic fibers (MF) enhance both resistance and rigidity more effectively than polypropylene fibers in small meshes (PPG/SM) and large meshes (PPG/LM), thereby limiting the formation of puncturing cracks.