Full-field experimental and numerical investigation of novel fire resistant fibre reinforced concrete for tunnel lining

The problem of tunnel fires is one of the most complex areas of fire research.

Under fire, concrete linings spall resulting in the collapse of the tunnel structure causing a significant scourge in the economy, society and the environment. In summary, the design of tunnel concrete linings is based on thermal calculations, which ignore spalling.

Based on such calculations new types of more durable, strong and hence denser concrete have been introduced on the market recently that are much more probable to spall due to their lower permeability.

To increase the permeability of the concrete and ultimately its fire resistance, it is commonly suggested to add polypropylene fibres. However, these tend to decrease the strength of the concrete and potentially its durability.

In FiRe2C I propose a new type of Fire Resistant, Fibre Reinforced Concrete to improve on the tunnel lining's performance and ultimately the post-fire structural stability of the tunnel.

To enhance our understanding of the performance of the Concrete on a multi-scale level, I will employ a holistic approach between state-of-the-art numerical (Discrete Element Method) and full-field experimental methods (advanced material and fire testing & x-ray computed tomography), pushing the existing boundaries of our scientific knowledge.

Specifically, I will study experimentally the effect of size, distribution and orientation of the fibres on the strength and fire-resistance of concrete linings, by employing full-field imaging techniques pre- and post-fire, which has not been done before.

And finally, I will create a novel DEM model to predict the thermo-mechanical response of fibre-reinforced concrete, utilising for the first time quantitative 3D experimental measurements at different length-scales to validate accurately the material response.