BIOMIMETIC MULTI SCALE DAMAGE IMMUNITY FOR CONSTRUCTION MATERIALS: M4L PROJECT OVERVIEW
This paper presents a vision of a sustainable and resilient built environment that is comprised of materials and structures that continually monitor, regulate, adapt and repair themselves without the need for external intervention. In this way, these self?healing materials and intelligent structures will significantly enhance durability and serviceability, improve safety and reduce maintenance costs. The conglomerate materials that form the basis of the majority of such construction materials (concrete, grouts, mortars, hydraulically bound materials, grouted soils etc) are extremely complex multiphase composites with multi?scale internal structures that exhibit a hierarchy of multi?dimensional, time?dependent damage mechanisms. For example, in cementitious composites nano?scale damage occurs during hydration and the strength development phase, while medium?term damage due to chemical attack also leads to the formation of defects in its structure. Other short?term factors can also produce dislocations at the nano scale. In time, this nano?damage grows to form micro cracks which eventually coalesce to form networks of meso?cracks which in turn lead to debonding between the paste and aggregate particles, followed by a discrete number of visible macro?cracks which so often lead to corrosion of the steel reinforcement. Hence, it is evident that to truly achieve a self?healing cementitious composite, a system is needed that can act at both the different time and length scales at which the damage can form. This paper presents a newly funded research project, M4L: Materials for life, that is addressing this complex problem by taking advantage of innovations in allied scientific disciplines to pave the way for the development of a new generation of versatile and robust construction materials.