The cuboid method for measurement of thermal properties of cement-based materials using the guarded heat flow meter

摘要

Contact resistance can significantly affect the measurement of thermal conductivity of cement-based specimens using contact methods. A new method is proposed which has a reduced time and material requirement compared with the currently accepted methods: the Cuboid method. The Cuboid method requires just one cuboid-shaped sample of relatively small contact area, surrounded by insulation board, while the currently accepted two-thickness and multi-thickness methods require at least two samples of contact area greater than the metering area of the apparatus. Results from the Cuboid method and multi thickness method were compared for specimens of Polymethyl methacrylate (PMMA) acrylic and hydrated CEM II Portland cement paste. The results differed by just 3.6% and 7.7% respectively for thermal conductivity measured in steady state condition. A non-steady-state method for the determination of specific heat capacity and thermal diffusivity of cement-based specimens, developed from the Cuboid method, is also presented. Relative uncertainties of the results for cement pastes measured in steadystate and non-steady state condition ranged from 2.2 to 11.5%. (C) 2018 Published by Elsevier Ltd.