The development and manufacture of mini-vascular networks to provide biomimetic multi scale damage immunity for construction materials
This research project is available as part of the EPSRC National Productivity Investment Fund (NPIF) Doctoral Training Partnership. Up to nine studentships will be awarded to the best applicants.
Engineers have long known that cementitious construction materials are particularly susceptible to cracking, which in turn aggravates deterioration because of the ingress of contaminants such as chlorides and sulphates. In addition, cracking can be exacerbated by mechanical and chemical actions such as freeze-thaw effects and carbonation.
The advent of self-healing cementitious materials, which take their inspiration from nature, has the potential to provide a remedy for this cracking by flooding areas of damage with a range of prophylactic agents, which act to seal and heal the crack, preventing further deterioration of the material. These prophylactic agents are held within either microcapsules or vascular networks. A procedure for forming 2D and 3D networks of small diameter channels in structural elements was developed in M4L (EPSRC grant no. EP/K026631/1) and while this procedure is considered viable for small to moderate sized structural elements and for the surface zones of larger structural elements, more efficient and reliable techniques are required.
Recent research conducted by Prof. Jefferson has considered the replacement of fibres in concrete by tetrahedral units (Tets). The research idea is to use skeletal tetrahedral units in a cementitious matrix to enhance its ductility, durability and strength. More importantly for the current project, these Tets show promise as a potential delivery system for self-healing agents.
This studentship will be strongly aligned to one of the research themes in the recently funded EPSRC programme grant “Resilient Materials for Life (RM4L)”, which has already been recognised as ground-breaking by EPSRC and Industry. RM4L will aim to effect a transformation in construction materials by creating smart materials that will adapt to their environment, develop immunity to harmful actions, self-diagnose the onset of deterioration and self-heal when damaged. The aim of this studentship will be to design, develop, manufacture and test a series of vascular systems and pressurised mini-networks containing innovative prophylactic agents.
The work will involve:
- further research into the optimum size and disposition of networks for a range of structural applications, for example, precast slabs, tunnel linings, basements, sprayed concrete, repair mortars, embankments and underground benching
- the formation of Mini-vascular-networks (MVNs) using 3D tetrahedral units of hollow ligaments with an overall size approximately equal to approximately twice the size of the maximum particle size of a composite
- establishing the optimum MVN shape, ligament aspect ratio, material type, bond properties and healing agent.
There is sufficient evidence from the EPSRC M4L project and preliminary studies conducted by MSc students, that the above is achievable within a 4-year period. Indeed, the aim would be to complete the project within a 3-year timeframe to facilitate the incorporation of the project outcomes into prototype products and demonstration projects, as identified in the RM4L grant application.
The project will employ and develop a series of key skills/techniques in conjunction with the RM4L project partners including:
- the development of vascular networks with smart walls (collaboration with Cambridge University)
- experimental data that contributes to the validation of numerical models that simulate the performance of cementitious self-healing materials, and the prediction of their future performance in service.
Moreover, through full integration into the RM4L programme grant activities, this studentship will benefit from input, review and constructive critique from the RM4L team, which brings together expertise in the areas of construction materials, structures, geotechnics, computer modelling, materials science, polymer engineering, nanomaterials, electrochemistry, biomaterials and microbiology.