Research on Electro-thermal Ice Melting of Steel Fiber Graphite Concrete
To verify that steel fiber graphite concrete can improve the heat transfer capacity of concrete,small slab specimens of steel fiber graphite concrete are made based on the optimum mixing ratio of the heat conductive material(1％by volume of steel fiber and 20％by mass of graphite in cement)and water-cement ratio(0.42),and small slab specimens of plain concrete are prepared as a test control group.Carbon fiber heating wires are selected as the heat source and pre-embedded in the specimen to perform the indoor heating and de-icing test.The test results show that:when the input power is 10.9 W/m,24.4 W/m and 43.7 W/m,the surface temperature of the steel fibre graphite concrete slabs can reach about 3.3℃,4.5℃ and 3.8℃ after 300 min,150 min and 90 min of heating respectively,and the average heating rate throughout is 0.046℃/min,0.100℃/min and 0.159℃/min,which is 12.20％,13.64％and 13.57％higher than that of the plain concrete slab.At ambient temperatures of-5.3℃,-10.5℃ and-16.7℃,the surface temperatures of the steel fiber graphite concrete slabs can reach about 7.8℃,5.8℃ and 7.6℃ after heating for 75 min,105 min and 150 min respectively,and the average heating rates during the whole process are 0.153℃/min,0.155℃C/min and 0.162℃/min,which are 14.38％,9.92％and 13.29％higher than those of the plain concrete slab.When the wind speed is 0m/s,1.8 m/s,2.7 m/s,and 3.4 m/s,the surface temperature of the steel fiber graphite concrete slab can reach about 3.2℃,2.8℃,3℃,2.6℃ after heating for 90 min,and the average heating rate of the whole process is 0.094℃/min,0.090℃/min,0.092℃/min,0.088℃/min,which is increased by 13.25％,16.88％,15.00％and 20.55％compared with that of the plain concrete slab.When the ambient temperature is-5℃ and the input power is 24.4 W/m and 43.7 W/m,respectively,the heating of the steel fiber graphite concrete slabs to melt the 1 cm thick ice layer takes 180 min and 150 min,respectively,which is 30 min earlier than that of the plain concrete slabs to complete the ice melting,and the time is reduced by 14.29％and 16.67％,respectively.The combined evaluation indices of heating rate and ice melting time show that steel fiber graphite concrete has a good heat transfer capacity and can be used to improve the heat transfer capacity of concrete.
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