We have been investigating paint deterioration except for thickness reduction.
We will introduce an investigation of paint deterioration.
Investigation of paint deterioration
Treatment for paint peeling
If the durability of the top layer improves, allowing the thickness reduction of the top layer becomes slowly, then the possibility that the peeling of the paint will determine the life-time of the paint increases. Therefore, we have been investigating the cause of peeling and method to evaluate the life-time of paint considering peeling.
Peeling of top layer
Paint specification for outer surface
Example of top layer peeling
From previous investigations, it is confirmed that chlorine has permeated to the intermediate layer. And it was suggested that this caused the delamination between the top layer and intermediate layer. Therefore, we compared a deteriorated paint due to chloride (hydrichloric acid, etc.) with a deteriorated paint of the actual bridge using an infrared spectrography test (microscopic ATR). From the investigation, it is confirmed that the spectrum resembled the paint that had been affected by hydrochloric acid. We will continue to investigate causes of peeling.
Accelerated deteriorarion paint
Infrared spectrography
Peeling of inorganic zinc rich paint layer
Paint specification for outer surface
Example of inorganic zinc rich paint layer peeling
X-ray diffraction test of paint collected near the inorganic zinc rich paint layer peeling of the actual bridge (photo above) was conducted. And it was confirmed that adhesion tends to decreases as zinc oxide increases, as shown in the graph at right. Because oxygen and water vapor are necessry for oxidization of zinc, we have been investigating the cause of peeling using tests of the permeability to gases of the paint (top layer, intermediate layer, under layer).
Relationship between zinc oxidization level and adhesion