Preparation And Performance Study Of Magnesium Oxysulfide Cement-based Foam Lightweight Thermal Insulation Wall Material

Magnesium oxysulfide cement is a kind of inorganic cementitious material with high strength,which is prepared by mixing light burned magnesium oxide with magnesium sulfate solution of appropriate concentration,uniformly stirring in a mixer,setting and hardening.The calcination temperature of light burned magnesia,the main component of magnesium oxysulfide cement,is much lower than that of Portland cement clinker.It has the advantages of low energy consumption,low cost and simple production process.Moreover,magnesium oxysulfide cement has the advantages of good heat resistance and fire resistance,high strength,low density,low thermal conductivity and strong material adhesion.Therefore,as a new type of inorganic cementitious material,magnesium oxysulfide cement is widely used in the preparation of light wallboard,thermal insulation board and fire-resistant components.Based on the characteristics of low density,high strength and low thermal conductivity of magnesium oxychloride cement,magnesium foam cement is used to prepare lightweight foam insulation material.Foam lightweight thermal insulation material is a new type of porous building material,which uses cement as the main cementitious material,which is introduced into the slurry by physical or chemical foaming,such as oxygen and carbon dioxide in the air and mixed with lightweight aggregate.It achieves the desired performance requirements through a certain process.It has the advantages of light weight,low thermal conductivity,sound insulation and fire resistance.Foam lightweight thermal insulation material itself has some defects such as long setting time and low strength.To some extent,the application scope of the material is limited.Therefore,this thesis uses magnesium oxychloride cement as cementitious material instead of Portland cement and sulphoaluminate cement to prepare foam insulation materials,so as to improve the defect of low strength of materials.With the development of agriculture,the treatment of crop waste has also become a difficult problem in agricultural development.In order to comply with the national building concept of energy conservation and emission reduction and green environmental protection,agricultural waste is used in building materials,and most crop waste has the characteristics of light weight and low thermal conductivity.Sawdust,rice straw and bamboo fiber were added to the thermal insulation material to adjust the thermal conductivity and the dry density of the insulation material.In order to explore the influence of crop waste on the physical properties of magnesium oxysulfide cement-based thermal insulation materials,tests were carried out on the dry shrinkage,water absorption,thermal conductivity,compressive strength,flexural strength,compression folding ratio and micro pore structure of the materials.It is found that adding pine sawdust and rice straw can improve the thermal conductivity of thermal insulation materials,but weaken the mechanical properties of thermal insulation materials to varying degrees;In order to improve the reduction of crop waste on the mechanical properties of thermal insulation materials,cellulose nanofibers with magnesium oxide mass of 0%,0.05%,0.1%,0.15% and 0.2% and polyethylene fibers（PE fibers）with cementitious material volume of 0%,0.2%,0.4%,0.6% and 0.8% are added respectively to explore the influence of their content on the mechanical properties and micro pore structure of thermal insulation materials.The experimental results show that the compressive strength of the material can be effectively improved,the flexural strength is slightly improved,and the flexibility of the material is reduced;When polyethylene fiber is added into the material,the compressive strength of the material is slightly improved.If the content is too high,the compressive strength of the material will be reduced,the flexural strength will be significantly improved,and the flexibility of the material will also be improved.The suitable content of cellulose nanofiber is 0.05% ～ 0.15%,and that of polyethylene fiber is 0.4% ～ 0.6%.