h i g h l i g h t s Calcium alginate capsules with rejuvenator are proposed for self-healing asphalt. Individual rejuvenator droplets are stored in porous media inside the capsule. The capsules are able to survive the asphalt mixing and compaction period. Calcium alginate capsules are capable of local crack healing in asphalt mix.

In recent decades, researchers have revealed the great healing potential of asphalt and proposed various novel methods to inspire and improve the self‐healing capacity of asphalt aimed to prolong the service life of asphalt pavement. In this review, up to date research progresses in induction healing and embedded rejuvenator encapsulation are presented, respectively. Meanwhile, the trial section applications of induction healing and capsule healing are highlighted, which show promising results. Finally, some recommendations for the future development of self‐healing asphalt are proposed.

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This paper explores the potential use of compartmented alginate fibres as a new method of incorporating rejuvenators into asphalt pavement mixtures. The compartmented fibres are employed to locally distribute the rejuvenator and to overcome the problems associated with spherical capsules and hollow fibres. The work presents proof of concept of the encapsulation process which involved embedding the fibres into the asphalt mastic mixture and the survival rate of fibres in the asphalt mixture. To prove the effectiveness of the alginate as a rejuvenator encapsulating material and to demonstrate its ability survive asphalt production process, the fibres containing the rejuvenator were prepared and subjected to Thermogravimetric Analysis (TGA) and Uniaxial Tensile Test (UTT). The test results demonstrated that fibres have suitable thermal and mechanical strength to survive the asphalt mixing and compaction process. The CT scan of an asphalt mortar mix containing fibres demonstrated that fibres are present in the mix in their full length, undamaged, providing confirmation that the fibres survived the asphalt production process. In order to investigate the fibres physiological properties and ability to release the rejuvenator into cracks in the asphalt mastic, the Environmental Scanning Electron Microscope (ESEM) and optical microscope analysis were employed. To prove its success as an asphalt healing system, compartmented alginate fibres containing rejuvenator were embedded in asphalt mastic mix. The three point bend (3PB) tests were performed on the asphalt mastic test samples and the degree to which the samples began to self-heal in response was measured and quantified. The research findings indicate that alginate fibres present a promising new approach for the development of self-healing asphalt pavement systems.

This paper presents the physical properties of Recycled Asphalt Pavement (RAP) and its influence on the mechanical performance of a binder course asphalt pavement mix. A series of binder course mixes were designed containing varying percentages of RAP. A mix made from only virgin material was selected as the control mix for the investigation. The effect of introducing RAP into the binder course mix was evaluated through a series of laboratory tests including the Marshall test, the indirect tensile stiffness modulus Test, the indirect tensile fatigue test and the water sensitivity test. A Circular Wheel Track (CWT) was developed in order to study the dynamic effects of a rolling wheel travelling over an asphalt pavement. The CWT was commissioned within a temperature controlled room along with a customised data acquisition system. The system involves the testing of rectangular slabs and allows for the investigation of dynamic tensile strain. The laboratory tests have shown that the introduction of RAP to the binder course mix resulted in an improvement in all mechanical properties. In particular, it was found that the mix containing up to 30% RAP, displayed improved fatigue resistance relative to the control mix manufactured from virgin materials.

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This paper explores the potential methods for evaluating a healing system for asphalt pavements. The healing system under investigation involves compartmented calcium-alginate fibres encapsulating an asphalt binder healing agent (rejuvenator). This system presents a novel method of incorporating rejuvenators into asphalt pavement mixtures. The compartmented fibres are used to distribute the rejuvenator throughout the pavement mixture, thereby overcoming some of the problems associated with alternate asphalt pavement healing methods, i.e., spherical capsules and hollow fibres. The asphalt healing efficiency methods to be evaluated in this paper include: (i) standard test methods for asphalt pavements, such as the Indirect Tensile Strength test and the 4 Point Bending Fatigue test; and (ii) alternative fracture tests such as the Semi Circular Bend test. The study employs fracture theory in order to evaluate the efficiency of the damage repair. The research findings demonstrate that including compartmented calcium-alginate fibres encapsulating a rejuvenator into an asphalt pavement mix does not significantly improve the healing properties of the asphalt pavement. Nevertheless, the findings indicate that, with further enhancement, compartmented calcium alginate fibres may present a promising new approach for the development of self-healing asphalt pavement systems. Additionally, the test results indicate that the 4 point bend fatigue test is the most suitable test for evaluating the performance of self healing asphalt pavements.

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