Study On Properties And Preparation Of Lightweight Steel-framed Foamed Concrete Panel

With the promotion of related energy-saving and emission-reduction policies,lightweight steel systems have been widely used in the construction and decoration industries.Low thermal conductivity insulation materials such as rock wool and glass wool are usually used as filling materials in the traditional lightweight steel system structure,so holistic properties of structures and mechanical properties are poor.The mismatch of the thermal conductivity between the filling material and the lightweight steel will cause thermal bridges effect,which leads to the increase of energy consumption and the decrease of durability.In this study,lightweight steel was employed as the support,and the calcium silicate board was employed as the surface layer.Foamed concrete slurry was poured between the panels between.After setting and hardening,the foamed concrete slurry is connected with calcium silicate board and lightweight steel to improve the integrity of the composite panel and reduce the thermal bridge effect.The research contents are as follows:Besides,on the basis of the characteristics of lightweight steel structure system,an exploration was conducted on the preparation process of lightweight steel-framed foamed concrete panel,and the technical parameters,pouring technology and optimization measures of foamed concrete suitable for lightweight steel structure system were proposed.The results showed that the basic performance parameters of foamed concrete were regulated as follows:the water-cement ratio was about 0.4,slurry expansion was about 230mm,the setting time was110-130min,and the density grade was not less than 600kg/m~3;Through the regulation of the above technical parameters,the compressive strength of foamed concrete could reach more than5MPa,and the slurry had good fluidity and stable pouring,and the early dry shrinkage strain was also small,which was suitable as a filling material for the lightweight steel structure;The addition of fiber and the arrangement of fiber grid cloth could reduce the shrinkage strain inside the composite panel.With the adoption of the horizontal type casting method to prepare lightweight steel-framed foamed concrete panel,the bonding strength of the calcium silicate board-foamed concrete interface can be increased by more than 30%.Aiming at the thermal bridge effect in lightweight steel structure system,the heat transfer performance and optimization scheme of lightweight steel-framed foamed concrete panel are studied.The heat transfer performance of ordinary foamed concrete panel,lightweight steel-framed foamed concrete panel and lightweight steel-framed rock wool panel was analyzed by ABAQUS finite element simulation analysis and laboratory test.The influences of thickness of the steel studs,the thermal break strip thickness,the thermal break strips position,length of the hole and row number of holes on the heat transfer performance of lightweight steel-framed foamed concrete panel were analyzed.The research results showed that there was a relatively small deviation between laboratory test results and finite element simulation results,which demonstrated that the established model was suitable for heat transfer analysis of lightweight steel-framed foamed concrete panel.Foamed concrete could be an alternative to rock wool as filling materials,which would reduce the influence of thermal bridge effect to a certain extent;The larger the thickness of the lightweight steel,the more obvious the thermal bridge effect.When the row number of holes was 5,the length of the hole was 90mm,and the thickness of the thermal break strip was 32mm with the arrangement on both sides of the steel studs,it could achieve the optimal improved effect for the heat transfer performance of the composite panel.In addition,an exploration was conducted on the flexural performance,axial bearing capacity and impact resistance of lightweight steel-framed foamed concrete panel.The influence of bulk density of foamed concrete and different reinforcement methods on the mechanical properties of composite panels,as well as the failure law of composite panel under various loads were analyzed.The failure process of lightweight steel-framed foamed concrete panel under load could be divided into elastic deformation,damage and failure of the calcium silicate board-foamed concrete interface,supporting effect of the steel studs and its yield deformation.The mechanical properties of lightweight steel-framed foamed concrete panel could be enhanecd through increasing the bulk density of foam concrete and three reinforcement methods including steel wire mesh,fiber and fiber mesh.The flexural performance and axial bearing capacity of composite panel could be improved best by using the reinforcement method of steel wire mesh.Compared with standard lightweight steel-framed foamed concrete panel,the flexural strength and axial compressive strength could be increased by 125.8%and 85.76%respectively.The reinforcement methods using fiber mesh could achieve the optimal effect in improving the impact resistance.Cracks would appear when the impact height was 2.5m,and the maximum energy absorption ratio was 96.57%.