Determination of tensile strength of concrete using a novel apparatus

Abstract

This study presents a new and novel technique for the determination of the tensile strength of concrete specimens. A prismatic concrete specimen with a hole at its centre is placed in a new device, called seesaw, and with the use of a conventional loading machine in compression mode, a tensile stress is applied to the specimen for the determination of the indirect tensile strength. In this study, two types of concrete mixes were used for preparation of specimens. The mixes were made of gravel, sand, cement, water, polypropylene fibre, and admixtures. Concrete specimens were subjected to tensile loading using a new load convertor device and a universal loading machine was used for the application of the load to the specimen. The load was applied at the rate of 0.02 MPa/s. The two dimensional finite element code FRANC2D/L was used for numerical modelling of the specimens and the loading conditions to determine the stress concentrations around the hole as a function of the hole diameter and the specimen width. Based on the results of experiments and numerical modelling efforts, a new formula for determination of the tensile strength of concrete is proposed in this study. Concurrent with indirect tensile tests using this new device, splitting test were performed to confirm the observed tensile strength values for concrete specimens. Both experimental and numerical modelling results show that the tensile failure occurs around the sides of the hole along the horizontal axis.