Design And Mechanical Properties Of UHPC Phosphogypsum Sandwich Thermal Insulation Shear Wall

Against the backdrop of increasingly prominent global resource and environmental issues and continuous breakthroughs in carbon emissions,China is accelerating its green and low-carbon transformation,and the development of building structures towards low energy consumption has become an inevitable trend.Shear walls,as important peripheral protection and load-bearing structures in building structures,are particularly important for their low energy design.However,there is still no unified low energy design standard established in the current specifications.If a large amount of phosphogypsum stockpiled can be applied to the wall,it can not only realize the utilization of solid waste,but also make the wall more thermal insulation and energy saving.In this paper,a new UHPC phosphogypsum sandwich thermal insulation shear wall panel is designed.Through structural design,material performance test,mechanical performance test and finite element simulation analysis,the proposed wall panel is studied to explore its optimal form,which is required to meet the requirements of heat transfer coefficient≤0.75W/(m2·K)in the Design Standard for Energy Efficiency of Low Energy Consumption Residential Buildings(DB42/T 559-2022).The main work and research results completed are as follows:(1)A new UHPC phosphogypsum sandwich thermal insulation shear wall panel is designed.The single panel is 3200mm high,1200mm wide and 200mm thick.The inner and outer structural layers of the wall are 50mm thick UHPC,the insulation layer is 100mm thick phosphogypsum based insulation material,and the connectors are 200×FRP bars with a spacing of 200mm.The heat transfer coefficient of the wall is 0.69W/(m~2·K),meeting the demand of low energy consumption.(2)Through the mix design and test of phosphogypsum based wall insulation materials,the optimal mix ratio is 50%phosphogypsum,50%expanded perlite,0.5%retarder,3%latex powder and 0.5%HPMC.The test results show that the setting time of phosphogypsum based wall insulation material is more than 30 min,the compressive strength is 1.62 MPa,the flexural strength is 0.5 MPa,the thermal conductivity is 0.08 W/(m·K),the dry density is 447.6 kg/m~3,the interface bonding strength with UHPC is 0.11 MPa,and the interface shear strength with UHPC is 0.061 MPa.Phosphogypsum based wall insulation material has realized heat preservation and light weight,and has certain mechanical properties when used for thermal insulation layer.(3)The research on the pull-out and shear performance of the connectors of the new UHPC phosphogypsum sandwich thermal insulation shear wall panel structure was completed.The tensile strength of the FRP connector with a diameter of 12 mm and an anchorage length of 35 mm was 9.9 MPa,and the shear strength was 2.5 MPa,which met the requirements of relevant specifications and ensured the integrity of the wall panel.(4)The shear performance research of the new UHPC phosphogypsum sandwich thermal insulation shear wall panel structure with thermal insulation layer was completed,which proved that the phosphogypsum based wall insulation material as the thermal insulation layer can improve the shear performance of the sandwich wall panel.The ultimate shear bearing capacity before cracking reached 177%of the sandwich wall panel without thermal insulation layer,and the ultimate shear bearing capacity reached 319%of the sandwich wall panel without thermal insulation layer.The plane size was 400mm×The average peak shear bearing capacity of the 400mm specimen increased from 19.55kN to 64.25kN.At the same time,phosphogypsum insulation layer and UHPC structural layer have certain cooperative performance,and the relative displacement of wallboard can be limited to 2mm before the interface between them cracks.(5)Abaqus finite element analysis was carried out,and the results showed that the integrity of the new UHPC phosphogypsum sandwich insulation shear wall panel was good,and the phosphogypsum based wall insulation material as the insulation layer was feasible,which showed better seismic performance than the traditional PU sandwich wall panel.Under the same load,the ultimate load of the wall panel is 210%of that of the cast-in-place C30specimen,and its energy consumption capacity is also better than that of the cast-in-place C30specimen.The cost and performance of the wall panel can be balanced by adjusting the concrete grade and thickness of each layer of the shear wall panel.The minimum thickness of the UHPC structural layer is 20mm.