*Article* **Application of X-ray Computed Tomography to Verify Bond Failures Mechanism of Fiber-Reinforced Fine-Grain Concrete**

**Grzegorz Piotr Kaczmarczyk 1,\*, Roman Kinasz 1, Vitaliy Bilozir <sup>2</sup> and Ivanna Bidenko <sup>2</sup>**


**\*** Correspondence: grzegorz.kaczmarczyk@agh.edu.pl

**Abstract:** This paper proposes the use of X-ray computed tomography (μCT, xCT) measurements together with finite element method (FEM) numerical modelling to assess bond failures mechanism of fiber-reinforced fine-grain concrete. Fiber-reinforced concrete is becoming popular for application in civil engineering structures. A dynamically developing topic related to concretes is the determination of bond characteristics. Nowadays, modern technologies allow inspecting the inside of the element without the need to damage its structure. This paper discusses the application of computed tomography in order to identify damage occurring in the structure of fiber-reinforced fine-grain concrete during bond failure tests. The publication is part of a larger study to determine the bonding properties of Ukrainian steel fibers in fine-grain concrete. The authors focused on the visual evaluation of sections obtained from tomographic data. Separately, the results of volumetric analysis were presented to quantitatively assess the changes occurring in the matrix structure. Finite element analysis is an addition to the substantive part and allows us to compare real damage areas with theoretical stress concentration areas. The result of the work is the identification of a path that allows verification of the locations where matrix destruction occurs.

**Keywords:** fine-grain concrete; bond; industrial computed tomography; numerical simulation; xCT; fiber
