Climate change resilient infrastructure for a sustainable built environment ('PermeableCity')

Permeable (fast draining) infrastructure will reduce the impact from climate change and urbanisation related flooding, which has a projected annual global cost of £500bn by 2030. Flooding is expected to cost the UK economy £27bn annually by 2080, without investment in flood resilient infrastructure. Along with the 2020 government plan for green infrastructure development, it is timely to invest in flood resilient permeable infrastructure. An extreme example of flood-affected infrastructure are airport pavements, impacted by stormwater and ice/snow build-up causing aircraft skidding. Skidding accounts for nearly half of all post 1990 major global commercial air crashes. In 2017 a Heathrow snow event grounded over 50,000 passengers and required a hurried £10m purchase of de-icing equipment. The current methods for preventing ice/snow build-up damage the environment, aircraft components and runway surfaces, increasing infrastructure maintenance costs. Airport operators, seeking to address these concerns, have expressed a strong desire to use permeable concrete technology to keep infrastructure clear.

Permeable concrete pavements are one of the most promising mitigation strategies to prevent surface flooding, they rapidly drain stormwater through otherwise impermeable infrastructure. Conventional permeable pavements are, however, prone to clogging, due to debris trapped within the pore network, blocking the pavement and reducing its drainage capacity. The frequent required maintenance degrades performance and service life and is difficult to perform in an active airport. Most importantly, conventional permeable pavements have insufficient strength, making them unsuited for airports. There is an urgent need for a new system that can reliably keep airports clear of standing water and ice/snow.

I recently developed next generation clogging resistant permeable pavement (CRP) of uniform pore structure to address infrastructure flooding. It has improved strength (twice as strong >50 MPa) and higher permeability (ten times more) than conventional systems of equal porosity, yet does not clog despite exposure to stormwater sediments.

This Fellowship will significantly reengineer my novel pavement to develop the first permeable pavement, with sufficient strength and resilience, for the extreme airport case, while also applicable to less extreme highway, railway and novel green wall scenarios. These step-change advancements will be achieved by steel reinforcement, used in permeable pavements for the first time. The structural performance, material integrity, skid resistance, long-term durability and hydrological (drainage) properties will be assessed for airport suitability and improved if required.

This project will be the first to investigate conductive (direct contact) and convective (transmission through air) heat transfer through permeable pavements used in high-value heavy load-bearing infrastructure. I will use heat extracted from the ground (ground source energy system, GSES) in these new pavements to melt the deposited ice/snow and drain away the excess water. Conventional pavements can be heated by conduction only, whereas CRP can be heated through both conduction and convection (via the pores) as the novel pore structure also allows for natural convection.

This Fellowship will, through extensive laboratory experimentation, computer modelling and the permanent large-scale deployment at Inverness Airport (spanning across multiple technology readiness levels (1-7), a measure of technology maturity), develop climate change resilient infrastructure materials that can be used to deliver a sustainable built environment resistant to flooding, ice/snow build-up and the harmful heat island effect. To achieve this ambitious goal, I will address significant structural, material, thermal and hydrological challenges with wide reaching economic, environmental and societal benefits to the construction and transportation sector.