Study On Mechanical Property And Thermal Insulation Technology Of New Cast-in-situ Phosphogypsum Infilled Wall

Phosphogypsum is an industrial by-product produced in the production of phosphoric acid.In 2015,the amount of phosphogypsum emissions in China amounted to 80 million tons,and the total storage capacity amounted to 300 million tons.Phosphogypsum not only occupies the land,but also pollutes the environment.Phosphogypsum has become an important factor restricting the sustainable development of phosphorus chemical enterprises of China.In the background of solid waste utilization,wall materials innovation and building energy-saving,it is of great significance to develop the wide-resource and large-scale comprehensive utilization technology of phosphogypsum.Based on the national science and technology support project“Research and demonstration on key technologies of building energy-saving of low cost and low energy consumption”(2011BAJ03B03),and Hubei science and technology innovation project“Effective utilization technology and industrialization of low cost and large scale of phosphogypsum”(2014ACC015),a new cast-in-situ phosphogypsum infilled wall is put forward,and the material preparation,mechanical property,thermal insulation technology and pouring technology of cast-in-situ phosphogypsum infilled wall are studied.The main research contents and conclusions are as follows:(1)Through the materials separate-mixed and composite-mixed rule test,the optimum proportion of new cast-in-situ phosphogypsum wall material is determined,which is 70%phosphorus-basedβ-building gypsum,30%fly ash,0.1%retarder,0.3%water-reducer and 20%vitrified microsphere;new cast-in-situ phosphogypsum wall material is prepared,and the thermal conductivity decreases to 0.16W/(m·K),and the volume density decreases to 728kg/m~3,and cast-in-situ phosphogypsum wall material realizes the objective of light weight and thermal insulation.(2)The basic and connected structure of new cast-in-situ phosphogypsum wall is designed;the basic mechanical properties of cast-in-situ phosphogypsum are determined by mechanical test;through the study of stress-strain relationship,the polynomial model,trigonometric function model and fractional model of stress-strain relationship of cast-in-situ phosphogypsum are determined,which provides the theoretical basis for the application of cast-in-situ phosphogypsum wall;through shock resistance and hang resistance test,it is determined that there is no through crack after 5 impacts on the cast-in-situ phosphogypsum wall,and there is no crack more than 0.5mm after hanging by 1000N.(3)Through the theory analysis of two-dimensional heat transfer,heat transfer coefficient of two-dimensional thermal bridge is put forward to evaluate the heat transfer performance of thermal bridge;the insulation structure and thermal bridge cut-off structure of cast-in-situ phosphogypsum wall are designed;through the thermal performance test,heat transfer coefficient of energy-saving optimization structure of infilled wall and shear wall are determined to be 0.55W/(m~2·K)and0.94W/(m~2·K),which achieves wall thermal insulation effectively;through the study of two-dimensional thermal bridge cut-off technology,heat transfer coefficient of two-dimensional thermal bridge of infilled wall/shear wall,shear wall/slab,infilled wall/slab thermal bridge are determined,and energy-saving optimization structure is decreased by 7.5%,14.9%,5.7%,and energy-saving extension structure is decreased by 20.8%,53.7%,14.4%,which achieves thermal bridge cut-off effectively;through the analysis of influencing zone of thermal bridge of shear wall structure,energy-saving design method of cast-in-situ phosphogypsum wall is proposed.(4)Through the pouring test,the construction method of cast-in-situ phosphogypsum wall is analyzed;through actual measurement,the surface roughness and verticality deviation of cast-in-situ phosphogypsum wall is determined to be3-4mm,the construction efficiency of cast-in-situ phosphogypsum wall is about6-7m~2/h,which achieves the objective of high precision and high efficiency of wall construction.In summary,the technology of cast-in-situ phosphogypsum infilled wall optimizes the mechanical performance of wall,and realizes the efficient energy-saving of wall,and realizes the high precision and high efficiency of construction.The technology of cast-in-situ phosphogypsum infilled wall provides an effective method for the wide-resource utilization of industrial solid waste as well as the large-scale innovation of wall materials.