Conductive Compartmented Capsules Encapsulating a Bitumen Rejuvenator

Abstract

This paper explores the potential use of conductive alginate capsules encapsulating a bitumen rejuvenator as a new extrinsic self-healing asphalt method. The capsules combine two existing self-healing asphalt technologies: (1) rejuvenator encapsulation and (2) induction heating to create a self-healing system that will provide rapid and effective asphalt pavement repair. The work presents a proof of concept for the encapsulation process, which involves embedding the capsules into the bitumen mortar mixture and the survival rate of the capsules in the asphalt mixture. A drip capsule production process was adopted and scaled up to the production of 20l wet capsules at rate of 0.22 l/min. To prove the effectiveness and its ability to survive asphalt production process, the capsules were prepared and subjected to thermogravimetric analysis (TGA) and uniaxial compression Test (UCT). The test results demonstrated that the capsules had suitable thermal characteristics and mechanical strength to survive the asphalt mixing and compaction process. Scanning electron microscopy (SEM) was employed to investigate physiological properties, such as rejuvenator (oil) and iron particle distribution, within the capsules. The electrical resistance tests proved that the capsules were capable of conducting electrical current. The capsules were also tested for their conductive properties in order to determine whether they are capable of conducting and distributing the heat once subjected to induction heating. The results showed that capsules containing higher amounts of iron (alginate/iron powder in a ratio of 20:80 by weight) can efficiently conduct and distribute heat. To prove its success as an asphalt healing system, conductive alginate capsules encapsulating a bitumen rejuvenator were embedded in a bitumen mortar mix. The samples where then subjected to local damaging and healing events, and the degree of healing was quantified. The research findings indicate that conductive alginate capsules encapsulating a bitumen rejuvenator present a promising new approach for the development of an extrinsic self-healing asphalt pavement systems.