The Mechanism and Mitigation of Fire-induced Spalling of Concrete with Recycled Tyre Fibres

In extreme conditions involving rapid heating and high temperatures, concrete can spall explosively. High-strength concrete (HSC) has a higher propensity for fire spalling compared to normal-strength concrete (NSC) due to its denser microstructure. To mitigate spalling, small amounts of micro-polymer fibres, such as polypropylene (PP) fibres, can be used to increase the permeability of concrete. This research aims to improve the sustainability of this mitigation method by investigating the potential of substituting manufactured PP fibres with Recycled Polymer Tyre Microfibres (RPTM) and Recycled Steel Tyre Microfibre (RSTM).

To examine the effects of fibres and other factors on fire spalling propensity, fire spalling tests were conducted on concrete specimens using a radiant panel heating system. The mechanisms of polymer fibres in fire spalling were investigated using Neutron and X-ray tomographies, which provided experimental evidence for the moisture migration process and changes in the porous structure of heated concrete.

The test results confirm the effectiveness of RPTM and RSTM in mitigating fire spalling supported by explanations of the underlying mechanisms. This research highlights the potential of utilising sustainable fibres, such as RPTM and RSTM, to mitigate fire spalling in concrete structures. Consequently, it contributes to the advancement of more environmentally friendly solutions for fire-resistant construction.