Measurement of the contribution of radiation to the apparent thermal conductivity of fiber reinforced cement composites exposed to elevated temperatures

•Radiative thermal conductivity of fiber reinforced cement composites is determined up to 1000 °C.•Fourier transform infrared spectrometry is applied in the wavelength range of 2.5–16 μm.•The expanded uncertainty of the measurement is 12.4–15.9%.•The contribution of radiation to the apparent thermal conductivity is up to 4.54%.

The contribution of radiation to the apparent thermal conductivity of fiber reinforced cement composites exposed to a thermal pre-treatment up to 1000 °C is investigated using Fourier transform infrared (FTIR) spectrometry. The transmittance spectra are measured in the wavelength range of 2.5–16 μm. The radiative thermal conductivity is then calculated using the spectral extinction and Rosseland mean extinction coefficients. Experimental results show that for the analyzed materials radiation can represent up to 4.54% of the apparent thermal conductivity. The expanded uncertainty of the measurement is found within the range of 12.4–15.9%, being affected by the accuracy of the FTIR spectrometer in the most significant way.