Crack Initiation and Growth in Indirect Tensile Tests of Steel Fiber-Reinforced Concrete Studies by Means of DIC

This study presents an advancement in the Brazilian test for assessing the tensile strength of concrete cubes through the introduction of a novel T-shaped loading mechanism equipped with a hinge arrangement. This innovation ensures the stability of the specimen and accurate centering of the load, leading to predictable crack propagation. Moreover, the research utilizes a cutting-edge Digital Image Correlation (DIC) system for the precise analysis of steel fiber-reinforced concrete specimens, enabling the identification of crack initiation points and their corresponding loads. The experimental findings confirm the efficacy of the DIC system as a superior alternative to conventional strain gauges, facilitated by the use of licensed GOM software for processing image series. This approach provides crucial qualitative DIC data, including detailed observations of major strains essential for understanding the local behavioral phenomena during indirect tensile tests. Particularly, the DIC system’s ability to pinpoint the exact moments of crack initiation significantly enhances the assessment of the indirect tensile strength and fracture behavior of concrete. Notably, matrix cracking in the tested steel fiber-reinforced concrete specimens was detected at roughly 60% of the tensile strength, highlighting the DIC system’s sensitivity and precision in early fracture detection. Overall, the integration of the T-shaped loading mechanism and the DIC system offers a comprehensive and robust framework for evaluating concrete’s tensile performance, markedly improving our understanding and assessment capabilities.