Preliminary Study On Thermodynamic Behavior Of Carbon Fiber Electric Heating Bellows-thermally Conductive Grouting Agent System

Prestressed bridges in western and northern alpine regions have common problems of pipeline ice heave,freeze-thaw disease.The existing common grouting agentprestressed piping system has poor thermal conductivity.Defects such as inability to actively adjust temperature.Based on the above question.This paper proposes to construct an electrothermal bellows-thermally conductive grouting agent system.In order to achieve the effect of active and uniform heating of the thermally conductive grouting agent in the bellows.Achieving the goal of smooth hydration and early strength of the slurry.The main research contents of the full text are as follows:(1)Mixing ratio test of thermally conductive early-strength grouting agent.Influence of external materials on the properties of grouting agent measured by laboratory experiments.Based on a water-cement ratio of 0.3.Incorporating 1.5%graphite thermal conductive filler.Its thermal conductivity is about 20% higher than that of ordinary grouting agent.And through the orthogonal test data analysis,the influence relationship between each factor and each performance is obtained.Then the optimal mixing ratio of thermally conductive early-strength grouting agent was determined.Its performance meets the requirements of current specifications.(2)Study on Electrothermal Properties of Carbon Fiber Electrothermal Bellows.Derive the electrothermal model of a single carbon fiber in air.The heat input in the carbon fiber electric heating bellows system has an exponential relationship with the surface temperature of the bellows.Simulation calculation of the steady-state temperature region of thermally conductive grouting agent at 50.Both can provide temperature conditions for the smooth hydration of thermally conductive grouting agent.(3)Preliminary study on temperature evolution characteristics of carbon fiber electric heating bellows-thermally conductive grouting agent system.The cooling curves of thermally conductive grouting agent and ordinary grouting agent were tested under the ambient temperature of-18.The effect of two carbon fiber arrangement methods on the temperature change of ordinary grouting agent and thermally conductive grouting agent was compared.Selecting a single carbon fiber arrangement method to carry out the grouting test in the beam body.There is an exponential relationship between the diameter of the bellows and the measured steady-state temperature of the grouting agent.(4)The mechanical properties of the thermally conductive grouting agent cured by the carbon fiber electric heating bellows-thermally conductive grouting agent system were tested.The results show that its strength is better than that of the thermally conductive grouting agent cured under standard conditions.And the thermally conductive grouting agent has excellent corrosion resistance.