Simulation Of Thermal Properties Of Composite Foam Concrete And Composite Thermal Insulation Roofing

In recent years,with more and more attention paid to energy saving and emission reduction by the state,reducing building energy consumption has been gradually concerned by people.At present,this kind of building thermal insulation material is mainly divided into two categories,one is organic thermal insulation material,the other is inorganic thermal insulation material.Although organic thermal insulation materials have the advantages of light weight,excellent thermal insulation performance and easy operation and processing,it is inevitable that organic thermal insulation materials will face flammable problems.Although the thermal insulation performance of inorganic thermal insulation materials is slightly worse than that of organic materials,they are non-flaumable and very beneficial to environmental protection.In this paper,the physical foaming method is used to prepare geopolymer cement from waste materials such as slag and fly ash by means of alkali activation,and then to prepare geopolymer foam concrete by combining with physical foaming technology.First,the influence of slag and fly ash content,sodium silicate modulus,water glass content,water cement ratio and foam content on the performance of foam concrete was studied by single factor experiment.The benchmark mix ratio of the foam concrete was determined.After that,the geopolymer foam concrete was modified,and the dry density and resistance were studied by adding expanded perlite particles,polystyrene particles and hollow glass beads.The influence law of compressive strength and thermal conductivity.Finally,the composite form of thermal insulation board which meets the requirement of heat transfer coefficient of roof in hot summer and cold winter area is calculated by thermal engineering,and the influence of composite mode on thermal insulation performance of composite roof panel is simulated by Comsol software.The research shows that the slag has the highest strength when the slag is 9:1,the content of sodium silicate is 9%,and the modulus of water glass is 1.When the water cement ratio is 0.45 and the foam content is 4L,the thermal conductivity of the foamed concrete is 0.101 W/(m·K),and the 28d compressive strength is 0.58MPa.When the optimum dosage of polystyrene particles is 1L,the dry density of foam concrete is 365 kg/m3,the compressive strength is 0.50MPa,and the thermal conductivity is 0.084 W/(m·K).When the optimum content of hollow glass bead is 10%,the dry density of foam concrete is 351 kg/m3,the compressive strength is 0.35MPa,and the thermal conductivity is 0.085 W/(m·K).The optimum content of expanded perlite is 1L,its thermal conductivity is 0.084 W/(m·K),compressive strength is 0.51 MPa and dry density is 293 kg/m3.The orthogonal test results show that the optimum ratio is water cement ratio 0.40,foam content 4L,polystyrene particle content 1.0L,the thermal conductivity is 0.081 W/(m·K),and the compressive strength is 0.42 MPa.The calculation of thermal engineering shows that the total heat transfer coefficient of geopolymer based foam concrete is 140mm,the thickness of vacuum insulation plate is 20mm,and the extruded polystyrene board(XPS)is 140mm.The heat transfer coefficient is 0.096 W/(m2·K),which meets the requirements of composite insulation roof panel heat transfer coefficient K<0.10 W/(m2·K).The simulation by COMSOL software shows that the heat transfer coeflficient of composite thermal insulation roof panel is 0.098 W/(m2·K)and the calculated heat transfer coefficient is 0.096 W/(m2·K)with an error of only 2%,within a reasonable range.The stacking sequence of materials has a great influence on the heat transfer process.The temperature difference between the two schemes is about 1 C.The composite material has little influence on the heat transfer process,and the temperature difference between the two schemes at same point is about 0.3 C.