The resilience of building and civil engineering structures is typically associated with the design of individual elements such that they have sufficient capacity or potential to react in an appropriate manner to adverse events. Traditionally this has been achieved by using 'robust' design procedures that focus on defining safety factors for individual adverse events and providing redundancy. As such, construction materials are designed to meet a prescribed specification; material degradation is viewed as inevitable and mitigation necessitates expensive maintenance regimes; ~£40 billion/year is spent in the UK on repair and maintenance of existing, mainly concrete, structures and ~$2.2 trillion/year is needed in the US to restore its infrastructure to good condition (grade B). More recently, based on a better understanding and knowledge of microbiological systems, materials that have the ability to adapt and respond to their environment have been developed. This fundamental change has the potential to facilitate the creation of a wide range of 'smart' materials and intelligent structures. This will include both autogenous and autonomic self-healing materials and adaptable, self-sensing and self-repairing structures. These materials can transform our infrastructure by embedding resilience in the components of these structures so that rather than being defined by individual events, they can evolve over their lifespan. To be truly self-healing, the material components will need to act synergistically over the range of time and length scales at which different forms of damage occur. Conglomerate materials, which comprise the majority of our infrastructure and built environment, form the focus of the proposed project. While current isolated international pockets of research activities on self-healing materials are on-going, most advances have been in other material fields and many have focussed on individual techniques and hence have only provided a partial solution to the inherent multi-dimensional nature of damage specific to construction materials with limited flexibility and multi-functionality. This proposal seeks to develop a multi-faceted self-healing approach that will be applicable to a wide range of conglomerates and their respective damage mechanisms. This proposal brings together a consortium of 11 academics from the Universities of Cardiff, Bath and Cambridge with the relevant skills and experience in structural and geotechnical engineering, materials chemistry, biology and materials science to develop and test the envisioned class of materials. The proposed work leverages on ground-breaking developments in these sciences in other sectors such as the pharmaceutical, medical and polymer composite industries. The technologies that are proposed are microbioloical and chemical healing at the micro- and meso-scale and crack control and prevention at the macro scale. This will be achieved through 4 work packages, three of which target the healing at the individual scales (micro/meso/macro) and the fourth which addresses the integration of the individual systems, their compatibility and methods of achieving healing of recurrent damage. This will then culminate in a number of field-trials in partnership with the project industrial collaborators to take this innovation closer to commercialisation. An integral part of this project will be the knowledge transfer activities and collaboration with other research centres throughout the world. This will ensure that the research is at the forefront of the global pursuit for intelligent infrastructure and will ensure that maximum impact is achieved. One of the primary outputs of the project will be the formation and establishment of a UK Virtual Centre of Excellence in Intelligent Construction Materials that will provide a national and international platform for facilitating dialogue and collaboration to enhance the global knowledge economy.

The vision of RM4L is that, by 2022 we will have achieved a transformation in construction materials, using the biomimetic approach first adopted in M4L, to create materials that will adapt to their environment, develop immunity to harmful actions, self-diagnose the on-set of deterioration and self-heal when damaged. This innovative research into smart materials will engender a step-change in the value placed on infrastructure materials and provide a much higher level of confidence and reliability in the performance of our infrastructure systems. The ambitious programme of inter-related work is divided into four Research Themes (RTs); RT1: Self-healing of cracks at multiple scales, RT2: Self-healing of time-dependent and cyclic loading damage, RT3: Self-diagnosis and immunisation against physical damage, and RT4: Self-diagnosis and healing of chemical damage. These bring together the four complementary technology areas of self-diagnosis (SD); self-immunisation and self-healing (SH); modelling and tailoring; and scaling up to address a diverse range of applications such as cast in-situ, precast, repair systems, overlays and geotechnical systems. Each application will have a nominated 'champion' to ensure viable solutions are developed. There are multiple inter-relationships between the Themes. The nature of the proposed research will be highly varied and encompass, amongst other things, fundamental physico-chemical actions of healing systems, flaws in potentially viable SH systems; embryonic and high-risk ideas for SH and SD; and underpinning mathematical models and optimisation studies for combined self-diagnosing/self-healing/self-immunisation systems. Industry, including our industrial partners throughout the construction supply chain and those responsible for the provision, management and maintenance of the world's built environment infrastructure will be the main beneficiaries of this project. We will realise our vision by addressing applications that are directly informed by these industrial partners. By working with them across the supply chain and engaging with complementary initiatives such as UKCRIC, we will develop a suite of real life demonstration projects. We will create a network for Early Career Researchers (ECRs) in this field which will further enhance the diversity and reach of our existing UK Virtual Centre of Excellence for intelligent, self-healing construction materials. We will further exploit established relationships with the international community to maximise impact and thereby generate new initiatives in a wide range of related research areas, e.g. bioscience (bacteria); chemistry (SH agents); electrochemical science (prophylactics); computational mechanics (tailoring and modelling); material science and engineering (nano-structures, polymer composites); sensors and instrumentation and advanced manufacturing. Our intention is to exploit the momentum in outreach achieved during the M4L project and advocate our work and the wider benefits of EPRSC-funded research through events targeted at the general public and private industry. The academic impact of this research will be facilitated through open-access publications in high-impact journals and by engagement with the wider research community through interdisciplinary networks, conferences, seminars and workshops.