Modern asphalt pavement and concrete structures are damaged much faster than older structures.As the damage progresses, gravelization that becomes only fine powder, blistering (expansion), peeling, cracking, amorphization, etc. occur, and safety is impaired, so the cause can be investigated by various methods. Although attempts have been made, this phenomenon has still been mysterious around the world.
A research group at Hokkaido University "accidentally" discovered that when commercially available concrete mixes with water, an unpleasant odor is instantly generated, so the substance hydrolyzed by phthalates is the cause of this odor. It was found that phthalates are also contained in a very small amount in deteriorated asphalt pavement and concrete structures.In addition, AE water reducing agents, surfactants in automobile washer fluids, surfactants in snow melting agents, etc. were also detected, so what kind of effects do these organic substances have on asphalt pavement and concrete structures? I decided to investigate.
The experiment was carried out by reproducing the same weather conditions (24-hour surface temperature, bottom temperature, relative humidity) as on a summer day when the surface layer was removed from the asphalt pavement runway.As a result, it was found that the structure itself takes in moisture in the air and various trace amounts of organic matter in a short period of time as the structure itself breathes as the outside air temperature fluctuates.It was also confirmed that even if asphalt pavement or a vinyl sheet is placed on concrete, moisture in the outside air and a very small amount of organic matter on the pavement surface easily pass through and accelerate deterioration.In other words, trace amounts of organic matter present in two places, in cement and in the air, are affecting the shortening of life.
The results of this research, which succeeded in elucidating the cause of the short life of structures for the first time, are expected to contribute to the development of technology for extending the life of asphalt pavement and concrete structures around the world.
Paper information:[PLOS ONE] Determination of modern concrete structures and asphalt pavements by respiratory action and trace quantities of organic matter
