| 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 mix to total shipment of hot mix asphalt (HMA) was increased up to 75%. Also, the content of RAP in recycled HMA 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 bitumen or recycled HMA, which compared with the property of virgin HMA, will be effected or not, including the extent of influence. And also the effects on the properties of recycled HMA. And also the effects on the properties of recycled HMA 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 HMA with rejuvenator or the RAP content. As the results, it is found that the properties of bitumen 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. From this study, 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. |
