The technology for recycling usage of reclaimed asphalt pavement (RAP) has been spread widely in 1980’s and now, it is authorized in Japan. Along to this, the ratio of recycled asphalt mixture to total shipment of hot mix asphalt (HMA) was increased up to 75%. Also, the content of RAP in recycled asphalt mixture has been growing year by year, the average of RAP content in the local areas is became between 30% to 60%. From this reasons, RAP which has experienced recycling repetitively with highly ratio of RAP content is concerned to be increased in the future.
However, it is not found that the properties of repetitive recycled asphalt or recycled asphalt mixture, which compared with the property of virgin asphalt mixture, will be effected or not, including the extent of influence. And also the effects on the properties of recycled asphalt mixture. And also the effects on the properties of recycled asphalt mixture by the ratio of rap or by usage of rejuvenator are not clear. The RAP is estimated to be recycled repetitively and continuously from now on. This study was conducted with aiming to present the suitable chemical composition of rejuvenator and the optimum ratio of RAP content, throughout the research of the effect on the properties of the repetitive recycled asphalt mixture with rejuvenator or the RAP content.
From test results, the findings are following. Repeatedly recycled asphalt has a softening point higher it becomes temperature sensitive resistance tended to decrease.
For the composition of repeating recycled asphalt, the asphaltene and the aromatic tend to decrease according to increase the recycling number.
The CI of repeatedly recycled asphalt tends to increase according to the recycling number.
The molecular weight distribution of asphalt repeated aging and recycling, according to a recycling number count increases, has a tendency that power of a large component (retention time 7.0 ~ 7.2min) to be increase. It is the same as the tendency of CI increases, it is seemed that the increasing in molecular weight in this experiment is considered to have large effect of oxidation.
From the results of split test and wheel tracking test for the repeatedly recycling mixture, it is considered to become "hard",and "low fatigue resistant".
Recycling with the rejuvenator of saturation rich for the recycled aggregate blending ratio 60% , since less is new asphalt to be added at the time of recycling, it is considered a component of increased aging and molecular weight by oxidation asphalt indicating that tends to be accumulated.
From these results, it cold be concluded that the properties of asphalt and HMA which is experienced aging and rejuvenation repetitively, would be influenced by the chemical composition of rejuvenator and the ratio of RAP content. Additionally, if considering of assumption the recycling HMA repetitively, it is necessary to take account of the chemical composition of rejuvenator to sustain the comparable high ratio of RAP.
Finally, it is clear that rejuvenator which contains less saturates and more aromatics is suitable for repetitive recycling. And also, without considering the composition of rejuvenator, it would be suitable to surpass the ratio of RAP content for repetitive recycling.
Durability and ageing , Development of testing methods and standardization , Development of design and modelling methods
