Experimental Study On Ordinary Portland Cement-based Light Thermal Insulation Material

As a kind of inorganic thermal insulation material,cement-based lightweight thermal insulation material has many excellent properties,such as light weight,fire-resistant,stable performance,non-toxic and harmless.It is applied in roof,wall and related construction projects.However,most of the cement-based lightweight thermal insulation materials are based on the composite of special cement or Portland cement and aluminate cement.Therefore,its high cost and poor durability restrict the wide application of cement-based lightweight thermal insulation materials.The research and development of cement-based lightweight thermal insulation materials with ordinary portland cement as the base material will promote the application of cement-based lightweight thermal insulation materials in practical projects.In this study,ordinary portland cement was used as the matrix material,and physical foaming technology was used to prepare cement-based porous thermal insulation materials.The apparent density,thermal conductivity,compressive strength,water absorption and porosity of the material were tested and analyzed by experiments.The effect of the amount of foam and the ratio of water to cement on the properties of the material was obtained.On this basis,the properties of styrene acrylic emulsion,organosilicon hydrophobic agent and polypropylene fiber were studied,and the effects of styrene acrylic emulsion,organosilicon hydrophobic agent and polypropylene fiber on the properties of various materials were analyzed.The main findings are as follows:(1)The percentage of foam content will directly affect the apparent density and strength of cement based porous materials.When the foam content is 6%,the apparent density of the material is 651.18 kg/m3,the thermal conductivity is 0.0934 W/(M·K),the 28d compressive strength is 1.67 MPa,the mass water absorption rate is 33.2%,and the porosity is 69.1%.(2)The water cement ratio has a significant impact on the performance of cement-based porous insulation materials.It can be concluded that when the water cement ratio is 0.50,the material has a good performance index.At this time,the apparent density of the material is 776.08 kg/m3,the thermal conductivity is 0.1111 W/(m·K),the 28d compressive strength is 1.78 MPa,the mass water absorption is 27.3%,and the porosity is 63.2%.(3)After adding styrene acrylate emulsion,the film with higher cohesive force can be formed on the surface of the pore structure.With the increase of styrene acrylic emulsion content,the apparent density,thermal conductivity and water absorption of cement based lightweight insulation materials are decreasing.When the content of styrene acrylic emulsion is 7%,the apparent density of the material is 454.58 kg/m3,the thermal conductivity is 0.0731 W/(M.K)and the water absorption is 26.3%.(4)After adding organosilicon hydrophobic agent,the hydrophobic membrane was formed in the material through a series of reactions,which effectively reduced the water absorption of cement-based porous thermal insulation materials.When the content of organosilicon hydrophobic agent is 0.4%,the mass water absorption of the material reaches the minimum value,only 22.2%,15.6%lower than the sample without organosilicon water repellent.(5)Adding a certain amount of polypropylene fiber can improve the mechanical properties of the cement based foam insulation material.When the polypropylene fiber content is 0.2%,the compressive strength of the material reaches the maximum and the 28d compressive strength is 1.19 MPa.Compared with the samples without polypropylene fiber,the 28d compressive strength increased by 18%.In this study,ordinary portland cement was used as the matrix material to prepare inorganic thermal insulation materials with light weight,good thermal insulation and hydrophobicity,which can meet the requirements of specifications for the strength of inorganic thermal insulation materials,and play a positive role in promoting the development of wall reform and resource intensive,environment-friendly construction industry in China.