# An Evaluation of the Efficiency of Compartmented
## 1 Introduction  
An EU directive recommending roads which are 'Forever Open' drives the need for improved asphalt pavement design, i.e., pavement materials and designs that will reduce road maintenance and improve safety levels for road users. Since 2008,'self-healing technology' for asphalt pavements has been advanced [1]. Incorporating this technology into pavement design offers the potential for road damage to be repaired by an internal (implanted) healing system, rather than by traditional road maintenance (which is costly and disrupts traffic flow). The objective of self-healing technology is to enable/assist material systems to heal after damage on a local or global scale, thereby reducing the level of damage and extending the functionality and life-time of the road. [PERSON] [2] defines the self-healing and self-repair of a material or system as: _\"the ability to substantially return to an initial, proper operating state or condition prior exposure to a dynamic environment by making the necessary adjustments to restore to normality and/or the ability to resist the formation of irregularities and/or defects\"_. To date, researchers have tested two methods for self healing in asphalt pavements [3; 4; 5; 6; 7; 8; 9; 10; 11]:  
* Induction heating, whereby electrically conductive fillers (steel fibres and steel wool) were added to the asphalt mix. Healing was initiated within the asphalt by sending an alternating current through the coil and generating an alternating electromagnetic field. When the conductive asphalt specimen was placed beneath the coil, this electromagnetic field induced currents flowing along the conductive loops formed by steel fibres [3]. The current caused the steel fibres to heat up, which heats and softens the aged bitumen, allowing it to flow and close the cracks, and to repair the damage. * Rejuvenation, whereby an encapsulated healing agent (rejuvenator) is added into the asphalt mix to restore the original binder properties. When micro cracks begin to form within the pavement system, they encounter a capsule in the crack propagation path. The fracture energy at the tip of the crack opens the capsule, releasing the healing agent which then diffuses within the asphalt binder to seal the crack. The potential benefits of applying self healing technology to asphalt pavements are clear [12]: reduced road maintenance with a subsequent reduction in CO\({}_{2}\) production, improved safety for both road users and road workers, improved road life span, and reduced cost of road maintenance. However, although research has demonstrated the potential benefit of an improved pavement performance via the incorporation of self-healing technology, it has not yet been universally accepted by the road industry. One of the biggest obstacles to its adoption is the absence of suitable standard testing procedures which could be used to evaluate the healing performance of the asphalt pavements mix. [PERSON] et al. [10] studied a modified Three Point Bend (3 PB) test system for the evaluation of asphalt mix containing capsules encapsulating a rejuvenator. [PERSON] et al. [12] also used a 3 PB test system to evaluate the healing effect of the mortar mix. The difficulty with this approach is in the asphalt mix; the mix is binder rich and has a higher potential to heal. Additionally, testing must be performed at low temperatures to avoid material deformation. While these approaches are suitable for proof of concept, more robust testing methods are required to convince the road industry to adopt self healing asphalt material as standard within the road design process. [PERSON] [13] and [PERSON] et al. [14] evaluated the performance of asphalt mixture when subjected to Indirect Tensile Strength (ITS), Indirect Tensile Stiffness Modulus (ITSM), and Indirect Tensile Fatigue (ITF) testing. However, these studies only reported on the comparative performance between asphalt mixes with and without healing agents, rather than the healing process itself. Most recently, [PERSON] et al.