Hiromi YAMASHINA

Prediction of Surface Distribution of Deterioration Accelerators in Concrete Structures

Fuminori NAKAMURA

To prevent salt damage, it is necessary to predict the progression of deterioration. In particular, since the progression of salt damage depends on the amount of salt on the structure's surface, it is important to estimate the amount of salt on the surface for prediction. Estimation of surface salinity requires simultaneous prediction of both the amount of salt blown into the structure from the sea and the amount of rainfall reaching the structure, which affects salt flushing and redistribution. In this study, experiments, predictive analysis, and validation were conducted to predict the surface distribution of salt transport and rainfall arrival at the structure surface.
In the experiments, the model was subjected to wind, airborne salts, and rainfall. The results showed that the wind distribution was affected by the model geometry, and that the arrival of flying salt varied greatly depending on the model geometry. In particular, models with overhangs had significantly different amounts reaching each location. The amount of rainfall arrival depended on the model geometry, and the distribution of rainfall varied greatly depending on the presence or absence of wind.
The predictive analysis was validated by a numerical analysis that reproduced the migration and arrival processes of airborne salinity and rainfall. As a result, the migration and arrival processes of rainfall and airborne salt particles were able to reproduce the experimental arrival distribution trends using the same particle tracking method. It was also shown that airborne salt particles are strongly influenced by the wind conditions around the model, while rainfall particles are strongly influenced by the model geometry.
The present study shows that the wind conditions differ depending on the model geometry, and that the arrival of droplets, rainfall, and the arrival location of the droplets are different. It was also shown that the same particle tracking method can be used for the migration and arrival processes of flying salts and rainfall to reproduce the distribution trends on the ground surface.　　
It is thought that similar arrival trends can be observed in actual structures and can be examined.