Hiyori EBINA Study on the Effect of Snow Preservation Spraying Cooling on Reducing Road Opening Time and Its Impact on Asphalt Properties Osamu TAKAHASHI This study quantitatively verified the effects of forced cooling using stored snow (snow-sprinkling cooling) on the temperature reduction behavior and material properties of asphalt mixtures immediately after paving, aiming for early traffic opening in summer pavement repair works. As a background, the significant time required for road surface temperatures to drop below the traffic opening criterion of 40C under high-temperature summer conditions has become a challenge, leading to a focus on the effective use of stored snow, a resource unique to snowy regions. In the first verification regarding the temperature reduction effect of asphalt layers, internal temperature monitoring using thermocouples was conducted. The results demonstrated that snow-sprinkling cooling has extremely high cooling efficiency compared to natural and water-sprinkling cooling, enabling traffic opening in as little as 22.5 minutes even under conditions where natural cooling fails to reach the reference temperature. Furthermore, a comparison of snow temperatures revealed that snow at 0C reduced the temperature in a shorter time than snow at -30C. This provided the practical insight that using cryogenic snow does not necessarily improve cooling performance, as 0C snow begins to melt earlier, allowing the resulting meltwater to continuously cool the asphalt surface. In the second verification evaluating the effects on asphalt binder (Straight Asphalt 60/80), a rigorous test involving 10 cycles of heating and snow-sprinkling cooling was conducted to confirm the presence of degradation due to rapid cooling loads. Penetration tests for physical evaluation showed no clear differences between cooling methods, indicating that forced rapid cooling does not impair the consistency of the asphalt. For chemical evaluation, four-component composition analysis via TLC-FID and infrared spectroscopy (FTIR) were performed. The Carbonyl Index (CI) derived from FTIR remained at a low value (0.27) after snow-sprinkling cooling, comparable to untreated samples and significantly lower than the value for degraded asphalt after long-term service (0.84), proving that no chemical alteration or oxidative degradation occurred. From these results, it is concluded that forced cooling by snow sprinkling is an effective and practical technology that can dramatically shorten curing times in summer without physical or chemical adverse effects on asphalt quality or durability. Future challenges include further quantitative verification of long-term performance as an asphalt mixture and the development of plastic flow deformation after traffic opening to further enhance the reliability of this technology.