Preparation and performance characterization of asphalt sustained-release capsules

In order to improve the self-repairing performance of asphalt pavement, emulsified-solvent evaporation method was used to prepare sustained-release capsules which wrap asphalt rejuvenator. The effects of stirring rate, core to shell mass ratios, stirring time and the amount of surfactant on the final morphology, particle size and yield of sustained-release capsules were studied by orthogonal experi-ment of four factors and three levels. The optical microscope and scanning electron microscope were used to characterize the sustained-release capsules. The experimental results show that the stirring rate has a great influence on the preparation of sustained-release capsules. The optimum conditions for preparing the sustained-release capsules are determined as the core to shell mass ratio of 0.6: 1, the surfactant of 1 g sodium dodecyl sulfate and 2 g gelatin, the stirring rate of 700 r/min, the stirring time of 30 min. The sustained-release capsules prepared under these conditions have a compact structure and good surface morphology. The sustained-release capsules are distributed uniformly in particle size, mainly in the range of 20–50 lm. The sustained-release capsules produced in this way have a high yield of 89.3%. Thermogravimetric analysis shows that the sustained-release capsules have good thermal stability. © 2018 Chinese Society of Pavement Engineering.