## 4 Evaluation Results
### Inclusive Comparison of the Four Types of Grout-Injection Materials  
Based on the above presentation of four types of grout-injection materials, a complete comparison of the physical property (waterproofing performance) changes are provided in the total radar chart of Figure 17.  
The comparison results showed that the polyurethane-foam grout injection had a more significant performance degradation (physical change) in six degradation factors than the other types of materials. In the case of SPRG grout-injection materials, their performance change was minimal relative to the changes displayed in other materials types. For acrylic-resin grout-injection materials, their performance change with respect to substrate movement and exposure to continuous water flow were shown to be high. For epoxy-resin grouts, property changes to chemical exposure were relatively high. For polyurethane-foam grouts, all products showed a high degree of property changes after exposure to all degradation factors.  
For the purpose of demonstration, a conclusion could be made based on the comprehensive evaluation results that the SPRG material overall had the least physical property changes (relative to the performance standard regimes and environmental degradation degree variables compliant to the KS F 4935 standard), but it is advised that, in construction sections where a constant presence of water or humidity, a usage of this material is not recommended. Similarly, acrylic-resin injection materials are subject to properties change where substrate behavioral stress is present, indicating that repairs with these materials in areas where a reopening of cracks due to settlement or vibrations is not recommended. Epoxy-resin grout usage should be avoided in areas where chemical substances are expected to be present. Polyurethane group-injection materials are generally not recommended to be used for repair in below-grade concrete structures as a standalone material.  
A decisive conclusion cannot be readily made on the performance of these repair materials in this particular paper, as the evaluation was conducted using product specimens from Korea that were already expected to have certain types of results, as a means to demonstrate this technical evaluation method. If other materials from different companies or countries were to be used, different results may be expected for the respective types of material products (although not significantly different). The priority of this paper is to propose this technical evaluation and its functionality in being able to measure the different ratios of property changes for any given types of injection-grout repair material. The results presented in this demonstration do not yet have substantial data to be able to conclude that a particular type of materials is best in different situations.  
In this regard, it must be noted that the tested specimens in this study have all been limited to samples manufactured in Korea; thus, the comparison results in this study alone is not sufficient to claim that one material type is undoubtedly superior over the other types. However, the technical evaluation model can be applied to different national products and material types based on the relevant national standard or specifications to control the variables in the testing regimes to establish a more objective comparison outcome.