Experimental Investigation On Concrete Pavement And Bridge Deck Deicing With Carbon Fiber Heating Wire

Deicing at the important locations, such as freeway, pedestrian bridge, airfield runway, side walks, and tunnel entrance, have an important practical significance to ensure road traffic safe and unblocked. By surveying the existing deicing and anti-icing methods and comparing them, a method of deicing with carbon fiber heating wire (CFHW) buried inside concrete slabs is presented in this paper to avoid the negative effects of traditional deicing salt on the structure, function and environment. In addition, CFHW is cheaper and has better electrical-thermal property than traditional metalic heating wire. Then the work is done in this dissertation using theoretical analysis and experimental method as follows.1. By the theory of heat transfer, the process of concrete slab deicing with CFHW belongs to nonlinear transient heat transfer issue of research object with inner heat source. The boundary conditions including thermal conduction, convection, radiation and the phase transition of ice and snow are involved in this issue. The important parameters related to thermal analysis of system deicing are described in detail. The finite element analysis of temperature field shows that the temperature difference on concrete slab surface is less than 2℃when CFHW spacing is not more than 100mm, which meets the temperature uniformity requirements for deicing. The change of CFHW cover thickness in the range of 20-60mm has the less influence on temperature distribution on concrete slab surface.2. In laboratory experiments of small-scale slab, CFHW with silicon gel coat was selected to be used in concrete deicing system by evaluating different types of CFHW. The slab heating experiments of different CFHW spacings indicate 100 mm CFHW spacing can meet the deicing requirements at-25℃, i.e., the temperature distribution on the slab surface is uniform and the average temperature can rise above 0℃within a given time period.3. When air temperature is-25℃, the range of temperature increment on slab surface is 10℃-30℃under different input power. The fitting result from the real values of experiments approximates a straight line. During the heating process, the environment temperature in refrigerator was stable, which verified the rationality of the experiment method of refrigerator simulating low-temperature environment. For different air temperature and ice thickness, the minimum input power of slab for deicing in 3h was summarized. Snow melting is more quickly than ice melting under similar situation. So in practice the road deicing should be done before snow turn into ice for saving time and energy. Another influence factors on slab heating, such as pre-heating, insulating layer, reinforcing steel bar wound around CFHW, were experimental researched.4. In field experiments, the production process of concrete slabs simulating pavement and bridge deck installed with CFHW is introduced. For these concrete slabs with three types of CFHW spacing, temperature uniformity of slab surface and the influence of wind force scale on slab heating were researched. The heating experiments of pavement and bridge deck model were analyzed and compared. The range of input power is 300-1000W/m2 for deicing experiments and deicing time is not more than 5.25h under different weather condition. The control circuit connection and working flow chart for control circuit of deicing system were studied and an operation mode of controlling switch by returning alarm signal obtained from temperature and humidity sensors was proposed. The analysis about net participants'cost and operation cost of concrete slab deicing with CFHW shows that this method has advantages of not only eco-friendly but also cost-effective.5. The ice pavement is determined as study object in finite element analysis of temperature field of concrete slab deicing with CFHW. According to experimental results of slab heating, a trial-error approach is proposed to determine the important parameter in finite element analysis of temperature field:thermal conductivity of concrete, and then it is applied in finite element analysis of concrete slab deicing. Compared with experimental results, the calculated ones show good agreement for the heating process of concrete slab deicing, which verified the validity of analytical method. Prediction results of concrete pavement deicing with CFHW in 3-4 hours by finite element analysis list the input power and CFHW spacing under different weather situation, which provides some references for designing CFHW spacing and selecting input power in the real projects of concrete slab deicing with CFHW.