Estimation of Post-Cracking Dissipation Capabilities of Fiber Reinforced Concretes in Three Point Bending Test Monitored with Application of Digital Image Correlation System

Abstract

Concretes with dispersed reinforcement are increasingly used in structural engineering. The basic source of knowledge on their application and design are the Model-Code 2010 guidelines. These guidelines, however, apply mainly to steel rebar reinforcement and are not fully sufficient in the analysis of the load-bearing capacity of elements made of concrete with dispersed reinforcement. Therefore, scientific research in this field is carried out continuously. The main goal of our work is to provide experimental data for the calibration of constitutive models of the cracking mechanics of concrete with reinforcement in the form of steel and polypropylene fibers. This article shows the possibility of using the digital image correlation system (DIC) to achieve this goal. The method of sample preparation and the method of conducting the tests were modeled on the recommendations contained in the PN-EN 14651: 2007 standard. The tests were carried out on prismatic elements with a notch loaded in a three-point bending setup. The results of standard strength tests are presented in the form of column graphs and tables. As an extension, the results of calculations of energy dissipated in fracture process are given. Moreover, the experimentally obtained graphs of the relationship between the force, displacement and crack opening were presented, which were supplemented with the images of crack development obtained with the use of DIC. The development of the crack net is characterized not only qualitatively but also quantitatively as a function of deflection or crack mouth opening displacement. Conclusions concerning the adopted research methodology and the tested materials are presented at the end of the article.

On the Calibration of a Numerical Model for Concrete-to-Concrete Interface

“…Figure 12 . Such a phenomenon can be examined using modern optical measurement techniques [ 27 ]. On the contrary, such techniques fail in monitoring fracture process for other analysed tests (the splitting and slant-shear tests) due to the brittle failure mode of such specimens [ 23 ].…”

“…The easiest way of testing the interface strength under compression and shear is a slant-shear test [ 25 ]. To determine the fracture energy of an interface, methods initially developed for homogenous concrete are used, like the three-point bending sample with a notch [ 26 , 27 ] or the wedge splitting test [ 28 ]. For a quick assessment of the strength properties of an interface, it is convenient to introduce the bond efficiency coefficient [ 16 , 29 ] which can be calculated as follows: where: and are the strength of the interface and the weaker concrete layer obtained from the same test method, respectively.…”

“…They took into account: advanced constitutive models for concretes and their interfaces as well as detailed geometry of the loading devices. It is worth mentioning that the progress of delamination of bi-material specimens is hard to follow with modern optical measurement systems due to their brittle failure modes, so only numerical studies could give a wider insight into this process at this point [ 23 , 27 ].…”

Strain Hardening of Polypropylene Microfiber Reinforced Composite Based on Alkali-Activated Slag Matrix

“…PP microfibers properties of the above-cited papers are presented in Table 1. A method is needed to assess the strength and deformation properties of the material in the structure under operating conditions [43][44][45]. The analysis of deformation curves and acoustic emission parameters can be used to evaluate the destruction of composites.…”

Experimental Comparison of Fibers and Nanomaterials in Compression Test and Cost of High Strength Concrete in Egypt

“…The main types of fibers added to concrete can be categorized into two categories: metallic such as steel fiber (STF), or synthetic for example polypropylene fiber (PPF) [7]. Steel fibers mainly offer crack control due to the ability of crack-bridging after cracking, which give tensile stress transfer across cracks [8]. The polypropylene fiber with higher…”