Internal asphalt mixture rejuvenation using capsules

• We have built capsules containing rejuvenators.
• We have mixed the capsules into asphalt mixture.
• The capsules reduced the viscosity of the mixture after a number of loading cycles.

The objective of this article is to present the effect of capsules containing low-viscosity oil in asphalt mixture when they break under simulated traffic loading. With this purpose, sunflower oil capsules have been built and their mechanical composition and strength characterised. Then, the capsules have been added to asphalt mixture, as another aggregate, and slabs have been built. To quantify the effect of capsules in asphalt mixture, slabs have been subjected to cyclic loading for different numbers of cycles, let to rest and tested again. The differences in amplitude between cycles before and after the rest period have served to quantify the effect of capsules in asphalt mixture. In addition, the opening and healing processes of cracks have been observed by inspecting asphalt mixture before testing, after the cyclic loading, and after the rest periods, using computerised tomography scans. It was observed that (i) capsules broke gradually during cyclic compression; and (ii) oil from broken capsules softened (rejuvenated) the asphalt mixture during the rest periods.

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