Methodology of Controlled Crack Introduction in Cementitious Materials

Abstract

Crack formation is a common and generally inevitable phenomenon in the field of concrete structures. On the other hand, the ever-increasing demand for sustainable construction, thus the structures durability, has led researchers to propose and investigate various crack-sealing methods. This study deals with the key aspect of these investigations – the in-vitro creation of cracks. A large number of the conducted studies have been carried out on artificially cracked specimens, and various methodologies of the controlled crack introduction were presented; however, no specific method was clearly preferred. In this paper, several approaches to the crack introduction are applied: cracking through compressive loading, tensile loading, and 3-point bending. Further, different types of specimens are presented: plain concrete, reinforced with short and long steel fibers, and reinforced with steel rod. The achievable crack characteristics, such as widths or its stability over time, are evaluated and compared. This study thus provides valuable overlook of the possible approaches to the controlled crack creation and points out their potential and limitations. Based on the comparisons presented in this paper, the long steel fiber reinforced concrete specimens subjected to 3-point bending are identified as the most appropriate method of crack induction.