## 2 Proposed Method for Quantifying and Classifying Defects in Concrete Surfaces  
The surface of concrete generally has many surface defects. These defects should be considered not only as aesthetic defects but also as structural defects that reduce the structural performance and durability of concrete surfaces. A quantitative and simple method for quantifying the defect volume is preferable for the evaluation of the quality levels of concrete surfaces.  
The aim of this research was to innovate and develop a method for supporting the objective evaluation of the quality of concrete surfaces. Therefore, an overall evaluation of quality requires the integration of a maximum of parameters. This objective evaluation reduces the discrepancies in quality evaluations. Consequently, we had the challenge of developing a method of evaluating of the level of defects to support the objective judgment of concrete surfaces' quality. The proposed method can quantify the values of all types of defects. Moreover, it is able to reveal all their positions and their infiltration into concrete, especially in the case of large surfaces, by establishing a quantitative survey of defects in terms of the area affected and the depth of the defects.  
The developed method is based on the quantification of the volume of defects on the concrete surfaces using concrete's absorptive properties. This is a quantification of surface defects through fluid penetration. The mass transport of fluids in hardened concrete refers to the ability of concrete, once it has cured, to allow the movement of liquids through its structure [47; 48].  
The capacity of concrete to absorb or take in a liquid varies depending on the concrete mix, its rheological properties, the degree of compaction, and the porous structure of the material [49; 50]. Furthermore, the penetration of liquids is a valuable and distinctive property that provides insights into the volumetric fraction of defects that are available for the transport of liquids through the structure of concrete when exposed to liquids. The porosity of concrete, which is determined by the size and distribution of its pores, has a significant impact on the transport of fluids across concrete surfaces. This mass transport characteristics are influenced not only by the presence of defects and their geometry but also by the extent to which these defects have infiltrated into the concrete [51; 52]. Thus, quantification of the defect volume in concrete constitutes a key factor in determining the concrete's durability and resistance to degradation. The larger the surfaces of defects and the more profound they are, the greater the potential for water, air, or harmful chemicals to penetrate and cause damage over time. Measuring the volume of surface defects can serve as a valuable indicator in quality control and manufacturing processes, as it can help identify defects that may affect the performance or appearance of concrete surfaces. A simple measurement method is needed to quantify defects distributed on a concrete surface.  
The proposed method uses concrete's property of fluid penetration by applying ready-mixed plaster (RMP) on a concrete surface. The amount of RMP that penetrates through a specific area of the concrete surface reflects the extent of damage in that area by quantifying the volume of the defects that are present; detailed surface information that can be an important parameter in the explanation of the affected proportion of the surface and can provide quantitative information on its quality is captured.