Mechanical properties and failure mechanism of carbon nanotube concrete at high temperatures

It is well documented that carbon nanotubes have better thermal stability compared with traditional polymer fibers, which enables application of carbon nanotubes to improve the performance of concrete at high temperature. In this work, the effects of carbon nanotubes on the compressive strength and microstructure of concrete at high temperatures are studied. The influence of temperature on the failure mechanism of carbon nanotube concrete is investigated. The experimental result shows that the carbon nanotubes inhibit further hydration reaction of the matrix at 300 ℃. The compressive strength of plain concrete increases more than carbon nanotube concrete at 300 ℃. The peak value of residual compressive strength migrates from 0.5% content of carbon nanotubes at room temperature to 0.3% content of carbon nanotubes at 600 ℃ and 900 ℃. A new failure mode of carbon nanotubes in concrete was observed at 600 ℃. A modified Matusinovic model is developed by introducing a function considering the influence of carbon nanotubes, predictions of the proposed model show reasonable accuracy compared with the experimental results.