Study On Application Of Self-limiting Temperature Heating Beltin Winter Concrete

The most important construction measure in winter is to provide reasonable curing temperature in order to prevent the cold damage of the concrete,and to ensure the normal operation of its hydration heat,as well as to accelerate the hardening.Common methods of maintenance include furnace heating,steam heating and electric heating.But the above methods have some problems in the use of the project site,for example,furnace heating adapt to the small space,and the coal combustion causes carbonization on the surface of the newly poured components;steam heating,the temperature of the whole process of curing can be controlled,but the cost is too high;electric heating,despite simple and convenient,the consumption of power is too large is its biggest drawback.Although all these methods can enhance the curing temperature of concrete in winter in order to succeed to cure the concrete,they also will be restricted by the construction site and external environment in the use in the field,as a result,generating a bad effect to the concrete curing.In order to solve practical problems in the field and to improve the quality of the project,this text proposes a new method of concrete curing in winter,the construction of thermal insulation model of the interaction of heating belt and air layer.Self-limiting heating belt has the following characteristics:Intelligent temperature control,when their own temperature elevates,the resistance increases,the power decrease.On the contrary,the power increases,repeating this cycle,ultimately reaching a stable temperature;Simple operation and the safe use,the layout is flexible according to the actual structure.Air,as a poor conductor of the heat,in the airtight situation,can be used as an excellent insulation material,in this paper,the air interlayer,as the insulation layer,has a protection of maintenance to the concrete.The role of the air interlayer are following:the air layer is a thermal insulation layer during the curing process;the electric heating belt and the air interlayer work together to increase the ambient temperature of concrete curing after heating.In this text,the experiment and simulation methods are adopted to analyze the curing scheme,and to study experiment and simulation of components from the perspective of temperature field.The main research contents are as follows:(1)Experiment studies the impact of heating belt and the different placement of components on the temperature field of concrete in winter and on the component strength.(2)Using MIDAS to simulate and analyze the test component under the same conditions,comparing the temperature field between the test component and the simulation component,and analyze the reliability of the simulation result.Simulation and analysis of the temperature field of components in different boundary.(3)Constructing the model of the inner environment of the interaction between the tropical zone and the air layer,and deducing the calculation formula of the length of the heating zone which is required for full and partial insulation of the outer surface to reach the preset ambient temperature and the curing temperature.The main conclusions are as follows:(1)Under the conditions of internal arrangement,surface arrangement and external insulation of the template,all the components of the heating belt reach the critical strength for three days after heating and curing,which shows that the heating belt can provide the temperature conditions for curing the concrete in winter.Comparing the temperature field with different arrangement locations in heating belt,the uniformity of temperature field in heating belt outside the template is better than the other two arrangements.(2)Using MIDAS software to simulate the temperature field of the actual test components,replace the tube cooling unit in MIDAS software with self-limiting heating belt.The temperature field of the simulation component is compared with the temperature field of the test component,and the change of the temperature of the measurement point is consistent.Using the self-limiting heating belt to replace the tube cooling unit in the MIDAS software can accurately simulate the temperature field of winter concrete curing.(3)Comparing the temperature field of the heating belt on the outer surface of the steel template and the wood template,the temperature field uniformity of the steel template is better than that of the wood template.Compared with the temperature field under the condition of full insulation,the temperature distribution of the simulated heating belt outside the template and the part of the outer surface of the component is greatly reduced compared with that under the full insulation condition.In order to ensure the temperature increase,the heating belt can be increased at the convection interface.(4)Based on the theory of heat conduction,the calculation formula of heating belt length can be used to calculate the length of heating belt in practical application.