# Management System According to ISO/IEC 17025: Method Validation
## 1 Introduction
This phenomenon of adhesion is attributed to the physical-chemical nature, facilitated by the capillary and molecular forces developed at the interface between steel and concrete. Here, the steel absorbs cement paste, aided by the retraction effect [2]. Adhesion failure occurs when the pulling force is transmitted to the concrete via the ridges or cords of the metal bar, creating an internal stress in a ring-shaped manner. This stress leads to cracks along the embedded metal bar. As the load on these rings increases until failure, longitudinal cracks emerge, ultimately causing the cone to fail at an angle of inclination, denoted as alpha. These cracks exacerbate the slippage between the bar and the mortar. Once the radial component reaches its peak, the mortar abruptly fractures [3]. Figure 1 illustrates this type of failure. One of the earliest studies on the adhesion phenomenon, referenced in the preceding paragraphs, dates back to the year 1899. This study involved measuring the displacement of the ends of steel cables embedded in mortar, followed by subjecting them to tensile loading. From this test, a force/displacement relationship was established, which became the standard method for measuring adhesion until the 1950s. This marked the inception of structural adhesion studies for materials. Figure 1: Adhesion failure. In 1958, [PERSON] publicly disclosed several results from an adhesion experiment, marking a significant development in the field. This experiment introduced the concrete rod extraction test, commonly known as \"The Pull Out Test.\" The experiment involved immersing a specially shaped steel bar into concrete, ensuring it was embedded within the steel body. Subsequently, the bar was subjected to tensile stress. Figure 2 illustrates this experimental setup. The results of the previous experiment led to the identification of two types of adhesion failures. In the first type, failure occurs due to bond breaking, characterized by the extraction of the steel bar accompanied by radial cracks in the concrete, emanating from the surface of the bar. In the second type of failure, damage to the concrete occurs due to the development of high internal stress, resulting in the appearance of longitudinal cracks parallel to the axis of the bar and spreading in the same direction [4]. In 1979, [PERSON] (1933-2015) pioneered one of the earliest formal scientific investigations into determining the resistance of metal bars subjected to tensile stress and the interaction between these elements. In this seminal work, the experimental interface was analytically modeled as a layer where both shear and internal pressure simultaneously play a role. As a result, it was proposed that the resistance of this interaction is determined by the ability of the surrounding concrete or mortar to withstand the circumferential stress induced by the steel bar [4]. This marked the inception of what is now known as the \"Determination of Strength in Anchors\" test. According to [5], the validation of test methods aims to ensure that the specified requirements are suitable for their intended use. During the validation process, the laboratory verifies the method's appropriateness for use, tailoring the validation extent to meet the application's needs. The methods employed for validation can include one or a combination of the following:  
* Measurement and precision measurement using standard samples. * Systematic evaluation of factors influencing the results. * Testing the method's stability by varying regulated parameters such as incubator temperature or dose volume. * Comparing results with those obtained from other validated methods. * Conducting inter-laboratory comparisons. * Estimating the uncertainty of measurement results based on an understanding of the method's theoretical principles and practical experience with the sampling or test method. These validation methods ensure that test methods are reliable, providing accurate and consistent results.