Study on the self-regeneration strategy of aged asphalt based on magnetic response controlled release microcapsules: A new sustainable self-regenerating pavement system

Microcapsule technology shows up-and-coming in enhancing the self-repairing capacity of asphalt. However, much of the current research on microcapsules focuses on passive release and single repair of cracks, which is not effective for aged asphalt that has not yet developed cracks. In view of this, in this study, a novel self-regeneration asphalt (MRCRM asphalt) capable of timed, quantitative, and multiple controlled releases was prepared based on magnetic response controlled release microcapsules (MRCRM). The controlled release kinetics of the MRCRM were investigated using ultraviolet–visible spectrophotometry (UV–vis). Subsequently, the variation law of MRCRM asphalt performance during aging was tested by DSR and FTIR tests, and a comprehensive evaluation index (P) for evaluating the performance change of MRCRM asphalt was constructed by combining with principal component analysis (PCA). Finally, P was used as a solution tool for a comparative analysis of the self-regeneration effect of MRCRM aged asphalt after five controlled release schemes. The results indicate that the release of MRCRM occurs in two stages: an initial burst release (0–10s) followed by a slower release (10–60s). The properties of MRCRM aged asphalt are restored after controlled release, and a reasonable increase in the controlled release time can help enhance the self-rejuvenation effect of MRCRM aged asphalt. On the contrary, a prolonged controlled release time can result in 'hot spot aging' and 'thermal overload' of the asphalt, which can impede the self-rejuvenation effect of MRCRM aged asphalt. In addition, MRCRM aged asphalt demonstrates a more apparent self-rejuvenation effect during the later stages of aging and the two-stage self-regeneration effect is superior to the single-stage. Finally, it is recommended to use scheme 3 as the optimal controlled release scheme. • The release kinetics of MRCRM can be divided into two phases: an initial burst release(0∼10s) and subsequent (10∼60s) slow release. • A comprehensive evaluation index that can include changes in the macro and micro properties of asphalt is proposed based on PCA. • Two-stage self-regeneration of aged asphalt is superior to single-stage. • Increasing the controlled release time facilitates the self-regeneration of aged asphalt. However, this approach may also give rise to 'hot spot aging'.