Flexural strength increases of concrete with AISI 4140 steel chip as reinforcement

Abstract

This work is an experimental and numerical study of the flexural strength increase in concrete with steel chips as reinforcement. The concrete was reinforced with different thicknesses of AISI 4140 steel chips: 1.0, 1.5, 2.0, and 2.5 mm, respectively. The metal chip replaced the sand in different percentages: 0 %, 15 %, 25 %, and 50 %. A two-level factor analysis was carried out to study the effect of metal chip thicknesses and their percentages on the flexural strength, making 13 different samples. Flexural tests were carried out in triplicate, making 39 tests. The 39 samples were weighed and measured. Flexural tests, the weights, and the measurements showed that the modulus of rupture and the density increase with the metal chip thicknesses and with its percentage from 2.20 to 2.55 g/cm3 and from 4.6 to 8.6 MPa, respectively. Numerical studies made by the Finite Element Method using Calculix® showed that the concrete can be simulated as an elastic isotropic material where the Younǵs Modulus can be supposed equal to the Flexural Modulus, except in the cracking zone of the concrete, where its behavior is not linear. Flexural tests and numerical studies showed that the mechanical behavior of concrete does not change significantly at the elastic zone, but after the elastic zone, when beginning the microcracking, the effect of metal chips as reinforcement agents is noticeable. The increase in flexural strength of the concrete due to the metal chips is noticeable after the first micro-cracks appear in the specimen.