Thermal Properties of Carbon Fiber-Reinforced Lightweight Substrate for Ecological Slope Protection

Abstract

A new ecological substrate is proposed to achieve a desired electric conduction and heating to protect the slope plants from freeze injury. Expanded polystyrene (EPS), cement, carbon fiber, graphite, and raw soil are the main components of the ecological substrate. The electrical conductivity, heating efficiency, thermo-sensitivity, and heat preservation of the substrate are experimentally investigated. The result shows that the addition of carbon fiber could significantly decrease resistivity of substrate, but the effect of fiber content exceeding 3% on the resistivity of substrate becomes insignificant. Conductive fine materials (i.e., carbon fiber and graphite powder) covering the surface of EPS would result in a significant reduction of the global resistivity of non-dry substrate, but it could only slightly affect the counterpart of the completely dry substrates. The substrate could hardly be formed when the EPS content exceeds 4%. As EPS content increases, the contact surface decreases and the resistivity of the substrate increases. The peak temperature at 30 min of substrate without root is higher than that of substrate with plant roots. Nevertheless, the temperature alteration ratio below 40 °C of substrate with plant root is nearly the same as its counterpart in the substrate without roots. The resistance of the substrate with plant roots increases with the temperature. The resistance of rootless substrate decreases by the heat action of the loosely bound water. EPS particles improve the heat preservation performance of substrate, but the heat preservation performance of substrate degrades with the growth of plants.