The Research Of Winter Concrete Construction Temperature Compensation

At present,China is in rapid development stage.National One Belt and One Road plan is driven infrastructure and various projects.Construction,turn towards large-scale,high-quality,fast cycle direction.With the accelerated pace of construction,winter is no longer a conventional construction off-season,concrete construction in winter phenomenon is more and more common,and to ensure the construction quality of concrete in winter to prevent frost damage occurs is the most important.Good curing conditions,and create a normal temperature required for hydration heat of concrete is the main guarantee of concrete construction in winter.Winter Construction currently has a variety of commonly used methods of conservation,such as stove heating,steam heating,infrared heating,electric heating.Stove heating,usually in a smaller site use,relatively dry,and CO2 emitted makes fresh concrete surface carbonation,affecting the quality.Steam heating,heating temperature easy to control.But it needs a special boiler equipment,cost is higher.infrared heating,need to on the concrete,sealed radiant heating.Electric heating.Use steel as electrodes,transforming energy into thermal energy to raise the temperature of the concrete.This method is simple and convenient,less heat loss,easy to control,but the downside is that the power consumption is relatively large.These passive external conservation method affected by the construction site building layers high,member and other factors,the use is not flexible enough.In this paper,for the lack of conventional curing methods,put forward new conservation methods,with built layout,self-regulating heating cable,to create a positive temperature curing environment.self-regulating heating cable has a smart temperature control features,Its power is mainly controlled by the ambient temperature,with the temperature of the heating system is automatically adjusts the output power.When the temperature rises,the resistance increases power reduction;when the temperature drops,the resistance decreases power increases,so again and again,and finally reaches the temperature balance.And traditional constant power heater does not have this feature,likely to cause local temperature is too high,causing the temperature cracks.In this paper,experimental analysis and finite element simulation analysis as the main body,to consider the effects of hydration heat temperature field of concrete,Experiment proves the feasibility of curing methods,finite element software to simulate the temperature field under different heating cable winding pattern.The main work is as follows:(1)From the temperature field theory and the theory of heat of hydration analysis start,derived heat conduction equation.(2)Experimental research,According to experimental data of different groups,analysis of factors affecting curing effect.(3)Using finite element analysis software MIDAS,to the test specimens,simulation analysis,comparison of experimental data and simulation data,analysis of factors affecting concrete temperature stress field.Obtained influence law of concrete temperature stress field.(4)Paper put forward: heating cable normal length formula and the minimum length using formula,for the practical application in the future,providing the calculation basis.The main conclusions: 1.Experiments show concrete specimens under the self-limiting temperature heating cable conservation 3 days to reach a critical intensity,prolonged heating cable heating curing time for concrete strength beneficial growth,but with little effect.2.From each specimen temperature curve measuring point total can be seen: Each measuring point temperature curve trend consistent margin is very small,indicating that the specimen temperature difference is small,temperature field uniformity.3.Test data indicate that under the same conditions of insulation materials conservation,conservation of electric heating heating rate main factors are: use of heating cable heating cable length and distance from the outer surface of the concrete.The peak temperature of concrete specimens,the primary and insulation materials and heating cable self-limiting temperature parameters.4.Specimen corners should increase the use of heating cable length to avoid frost damage corners occurred due to poor insulation,and can balance the temperature field.5.The paper,MIDAS simulation results and measured data is very consistent,description of MIDAS,can provide theoretical support for temperature compensated concrete temperature stress field,also provide a reasonable reference for the construction.