## 4 Conclusions  
This study sought to investigate the performance change characteristics ( deterioration characteristics), according to the reclaimed butyl rubber content in a chemically deteriorated environment, when the rubber material of the self-adhesive waterproofing sheet was changed from a new material to reclaimed butyl rubber, thereby suggesting a proper range for the reclaimed butyl rubber content in order to ensure adhesion performance. The major findings of this study are summarized as follows. 1. It was confirmed that the adhesion property of the sheet material compound decreases when the reclaimed butyl rubber content of the self-adhesive waterproofing sheet increases. In particular, when the reclaimed butyl rubber content is 100%, the rate of performance degradation is more than 74% compared to that of the plain specimen under chemically deteriorated conditions. In the case of new butyl rubber, adhesion performance is determined based on the material properties of the rubber itself, but in the case of reclaimed butyl rubber, other raw materials are included in the composition, which results in lowered adhesion strength. 2. The adhesive strength and peel strength were found to be below the performance standard when the ratio of reclaimed butyl rubber content to the total rubber content  
Figure 14: Adhesion performance test result (between sheet joint). Figure 15: Result of the quality assurance. exceeded about 56%. This is because, in the case of new butyl rubber, the homogeneously structured rubber layer can fundamentally respond to the deterioration environment, whereas reclaimed butyl rubber, due to the presence of other material compositions, cannot respond uniformly to the deterioration environment. That in turn results in reduced strength, and the effects of chemical deterioration are greater if the mixture ratio of reclaimed rubber is higher. 3. It was confirmed that when exposed to acidic environments such as hydrochloric acid, nitric acid, and sulfuric acid, compared to alkali or sodium chloride treatment among chemical degradation environments, the performance degradation rate was relatively higher. In order to select a material with stable quality performance considering the degree of deterioration of the material due to deterioration conditions, the content of reclaimed butyl rubber must be limited to 44% or less. Performance exceeding the KS national quality standard was confirmed to be obtainable. Through the above results it is suggested that the appropriate mixing range of regenerated butyl rubber is up to 44% compared to the total rubber content, considering the performance degradation due to the elapse of sealing after field application when manufacturing self-adhesive waterproofing sheet. This study is significant in that it suggests the minimum mixing range of reclaimed butyl rubber in order to ensure performance in a chemically deteriorated environment in relation to the utilization of reclaimed butyl rubber for the production of self-adhesive waterproofing sheets. The mixing range suggested in this study is expected to be used as data applicable to the mix design for the practical application of self-adhesive waterproofing sheets using reclaimed butyl rubber. However, this study has its limitation in that functional additives are excluded from the basic mix design. Therefore, in the future, additional research is needed in order to expand the range of reclaimed butyl rubber content based on the performance improvement effect via functional additives. In addition, there is a need to conduct research regarding performance change characteristics applied with physical deterioration factors (cracking behavior, fatigue resistance performance, etc.) in addition to the chemical deterioration factors established in the present research. [PERSON], [PERSON] and [PERSON] conceived and designed the experiments; [PERSON], [PERSON] and [PERSON] performed the experiments; [PERSON] and [PERSON] analyzed the data; [PERSON] and [PERSON] wrote the paper.