## 4 Conclusions  
This study aimed to determine the optimal viscosity level for SPRG materials for wet surface application on substrate surface. It is important to be aware that, with the development of new waterproofing materials with inherently higher adhesive performance than most other types of existing waterproofing materials, they come with the downsides that (either or both) (1) their workability performance is low and (2) they have higher costs. With these circumstances, if the use of materials like SPRG is strongly advised by the designers when building new structures, attempts on construction costs reductions will usually follow, one method of which is by reducing the allotted construction time. In these circumstances, cases can occur where waiting for the recommended dry level of concrete before waterproofing application is a luxury builders are not willing to afford, as a common misunderstanding is that the adhesion strength of the installed waterproofing material will still be adequate enough. The problem is that there is not yet clearly experimented data results on an SPRG-like material's adhesive strength performance on wetted concrete surface  
Figure 7: Adhesive strength result difference between 0% and 100% surface humidity ratio of each specimen type. and, as the data of this study shows, the adhesive strength is quite varying. Therefore, it is very important to alert contractors to these types of information through the publication of this paper. Specifically, this paper sought to analyze the relationship between viscosity and different rates of change in adhesive performance in varying humidity ratios, which had not been studied in previous research, and to quantitatively determine the viscosity level at which stable adhesion is possible for different functional ratios of the backing surface. The key findings of this study are as follows:  
1. A regression analysis was conducted to examine the correlation between viscosity-adjusting agent concentration and changes in viscosity, adhesive performance for different backing surface humidity ratios, and adhesive performance for different viscosities. Based on this regression analysis, we determined the optimal viscosity range that can adapt to the humidity environment for each humidity ratio of the backing surface. Additionally, viscosity standards were provided that meet the KS quality criteria for commercializing resource-circulating adhesive waterproofing agents: a minimum viscosity of 2,500,000 mPa-s and a maximum viscosity of 5,000,000 mPa-s, considering on-site workability. 2. Based on the regression equations derived from the adhesive strength evaluation, the adhesion strength difference of each specimen type between the 0% humidity ratio condition (completely dry) and 100% humidity ratio condition (completely wet) were derived. A conjecture was provided that these findings can help in developing a stable mixing design for manufacturing SPRG by deriving an optimal trade-off of viscosity modifier ratio and workability, enabling more consistent quality control during their application on site. This study is significant in that it provides insight into how to improve the adhesion stability of existing adhesive waterproofing materials in humid environments. However, this study is limited to the waterproof engineering aspects of one product type of SPRG. To build a stable database, further research and analysis on the performance evaluation that include more types of SPRGs is necessary. This could help improve the quality stability of waterproofing agents under continuous weathering conditions, making it essential to consider as future research directions. Conceptualization, J.-K.K., K.-H.O., S.-T.P., B.J., S.-K.O. and B.-S.K. ; Methodology, J.-K.K., J.-Y.L., S.-T.P., S.-K.O. and B.-S.K. ; Experimental plan, J.-K.K., J.-Y.L., K.-H.O., S.-T.P. and S.-K.O. ; Formal analysis, investigation, resources, data curation, J.-K.K., J.-Y.L., K.-H.O., S.-T.P. and B.J. ; Writing--original draft preparation, J.-K.K., J.-Y.L., K.-H.O., S.-T.P., S.-K.O. and B.-S.K.