Unlocking the role of recycled polymer fibres on dynamic fracture characteristics of concrete after exposure to elevated temperatures

Abstract

This work explores the dynamic fracture characteristics of recycled tyre polymer (RTP) fibre reinforced concrete after exposure to 20, 105, 250, 400 and 600 °C. Split Hopkinson pressure bar tests were performed to characterize the dynamic compressive properties under strain rates of 40–120 s⁻¹, in terms of the failure mode, strain-stress response, dynamic strength, dynamic increase factor (DIF), peak strain and energy absorption capacity. Results indicate that the failure pattern varies from splitting failure to core failure, and finally to pulverization failure due to strain rate effect, regardless of exposure temperatures. The dynamic strength and DIF are enhanced by strain rate effect but drop by 56.1% and 23.9% at 600 °C, respectively, while no explosive spalling occurs because of the thermal expansion of RTP fibres. The temperature-dependent dynamic fracture mechanism is closely related to the physicochemical reactions in the concrete matrix, bridging or rupture of RTP fibres and breaking of coarse aggregates.

Keywords:

• Dynamic fracture behaviour
• fibre reinforced concrete
• high temperatures
• recycled tyre fibre
• damage evolution

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors gratefully acknowledge the financial support by the National Natural Science Foundation of China (52178382, 52308395), the China National Postdoctoral Program for Innovative Talents (BX20230063), the Fundamental Research Funds for the Central Universities (N2201023, N2301023), the China Postdoctoral Science Foundation (2023M730526), the Doctoral Startup Foundation of Liaoning Province (2023-BS-058), and the Northeastern University Postdoctoral Foundation (20230204).