Influence of nano-SiO2 and nano-Al2O3 additions on the shear strength and the bending moment capacity of RC beams

In the study herein presented, the influence of nanoparticles additions on the structural behavior of reinforced concrete beams is analyzed, in terms of both shear strength and bending moment capacity. For this purpose, concrete mixtures with additions of either silica nanoparticles (nano-SiO2) or aluminum nanoparticles (nano-Al2O3) were produced. An experimental program was organized in two different sets: i) eight beams tested until shear failure was reached; and ii) eight beams tested until failure in bending was observed. These beams were produced with eight distinct concrete mixtures, with and without nanoparticles, and with and without steel fibers. Based on the data recorded, the following was analyzed: the force-displacement curve, the maximum strength in shear and in bending, the average curvature at critical cross-sections, the bending stiffness, the cracking pattern, and the failure type. It was concluded that the addition of nanoparticles, mainly nano-Al2O3, to the concrete mixtures can lead to a strength increase, both in shear and in bending. It was also concluded that the interaction between the nanoparticles and the steel fibers can have a negative effect on the beams strength.