Microscopic and rheologic characterization of third generation self-repairing microcapsule modified asphalt

Abstract

The feasibility and potential application of microencapsulated rejuvenator for self-healing of asphalt materials has been of great interest for the past decade, but the strategy of repairing uncracked aged asphalt remains a major challenge. Herein, a magnetically responsive controlled release microcapsule with a “honeycomb” structure was developed. A new microscopic experimental sample preparation method was developed using optical inverse bright-, darkfield and fluorescence microscopy (OIM) to observe the microstructure of microcapsules and asphalt. Image J software was applied to quantitatively analyze the area ratio of microcapsules and the dimensional characteristics of the bee structure. DSR tests were performed to evaluate the effects of microcapsules on the complex modulus and phase angle of asphalt, as well as the rheological properties under low temperature. The results showed that the microcapsules maintained the structural integrity in the asphalt with large errors in their area statistics, and the results of the high microcapsule admixture samples were closer to the true values. Microcapsules have almost no effect on the basic rheological properties of asphalt, reflecting the fact that the microcapsules survive after high temperature mechanical mixing with asphalt.