Ryotaro Hara

Outdoor experiment and transport analysis of salinity supplied to atmospheric space from road surfaces

Takumi Shimomura

The prediction of salt amount due to anti-freezing additives at structural surfaces is important on countermeasures against salt damage of concrete structures. In this study, indoor experiments and numerical calculations to estimate the salt concentration of moisture on the road surface, were conducted. Also, experiments were performed to evaluate droplets amount and its particle size when these are supplied in the atmosphere due to the effect of cars running through road surfaces. Furthermore, numerical simulations, regarding transportation and reaching process of droplet particles, were carried out and its influence on concrete structure was assessed.
Regarding the salt concentration of moisture on the road surface, it was confirmed about 3% of salinity concentration of moistures on road surfaces of Niigata prefecture. In addition, it was shown that the numerical simulations can simulate the time-changing of salinity concentration of experimental data.
On the other hand, experimental observations confirmed that the amount of splash that is supplied from road surfaces to the atmosphere due to the effect of cars running, can be expressed as an exponential distribution decaying in vertical direction. Also, observing particle diameters of droplets generated by the effect of cars running, it was verified that droplet particle size of 200 ƒÊm or less represents from 80 to 90% of all volume ratio of the particle size.
Furthermore, numerical computations were carried out on actual bridges where anti-freezing agents were actually applied, and its effect on concrete structures located in the bridge leeward was evaluated. As  result, it was confirmed that splash particles supplied from the road surface to the atmosphere on the bridge girder reaches the surfaces of surrounding structures due to the influence of girder shape.