Research On The Fabrication And Frost Resistance Of Cement-Based Solar Energy Absorbing Material

In recent years,with the development of economy,energy crisis and environmental pollution have become two major social problems that plague mankind.Due to the huge consumption of fossil energy by human beings,fossil energy is gradually exhausted,and fossil energy is a non-renewable resource.The combustion of fossil energy will produce air pollutants,cause haze,and also produce greenhouse gases,leading to the greenhouse effect.Therefore,the development of new energy is imminent.Solar energy is a clean energy,harmless to the environment,low cost,and the annual solar radiation reaching the surface of the earth is equivalent to about 130 trillion tons of coal.However,its disadvantages of dispersion,low efficiency and high cost limit the application of solar energy.If solar energy absorption is combined with cement concrete buildings,it will greatly improve the application range of solar energy,reduce the cost of solar energy application,and realize the integration of solar energy and buildings.At present,the cement concrete commonly used in buildings has good mechanical properties,but the light absorption performance and thermal properties are lacking.Therefore,our research group has carried out a lot of preliminary exploration work to enhance the light absorption and thermal properties of cement concrete.Iron oxide black,graphite and carbon black were doped into cement as admixture to prepare cement-based solar energy absorbing materials that meet the construction requirements.Although the addition of a large amount of admixture will greatly reduce the mechanical properties of cement concrete,the porosity of cement-based solar energy absorbing materials can be reduced and the mechanical properties can be improved by the method of low water-cement ratio compression molding compared with the traditional grouting molding.In order to improve the mechanical properties and light absorption properties of cementbased solar energy absorption materials.Firstly,the effect of cerium dioxide on the properties of cement was studied.The single addition of cerium dioxide can improve the mechanical properties and thermal properties.When the external content is 3wt %,the compressive strength and flexural strength reach 89.45 MPa and 21.97 MPa.When iron oxide black,graphite,carbon black and cerium oxide are mixed,the mechanical properties of cement-based materials are reduced,the thermal properties and light absorption properties of the materials are improved,the thermal conductivity is increased to 5.4146 W /(m·k),the actual temperature is increased to57.45°C,and the whiteness is reduced to 15.07%.At the same time,with the increase of cerium dioxide content,the absorption coefficient of cement-based solar absorbing materials to shortwave ultraviolet light is improved.Insufficient durability will cause structural damage,so durability is a key factor in the practical application of cement concrete.As an important part of durability,the frost resistance of concrete is one of the important problems to be solved urgently in cold areas.Therefore,the effects of iron oxide black,graphite,carbon black and cerium oxide doping on frost resistance were studied.The single doping of iron oxide black,graphite and carbon black will reduce the frost resistance of cement-based materials.The single doping of cerium oxide enhances the frost resistance of cement-based materials.The compound doping of endothermic thermal conductive phase and cerium oxide will greatly reduce the frost resistance of cement-based materials.After multiple freeze-thaw cycles,the cement sample will appear surface spalling due to the action of hydrostatic pressure and expansion force.After multiple freeze-thaw cycles,the interior of the cement sample becomes loose,the pore size of the specimen becomes larger,and the small pores are densely connected to form larger pores,and the pores are connected to form microcracks,and the mechanical properties are greatly reduced.