Research On The Influence Of Glass Fiber Mesh Aperture On Fire Risk Of Building External Wall Insulation Layer

The insulation layer of building exterior walls is flammable,highly toxic,and has a high fire risk.As an important component of the exterior wall insulation system,glass fiber mesh has a certain impact on the fire risk of the composite layer.This thesis selects three types of insulation materials: molded polystyrene(EPS),extruded polystyrene(XPS),and polyurethane(PUR),and composites them with glass fiber mesh of 7mm,5mm,and 4mm pore sizes.Theoretical analysis,experimental research,numerical simulation,model evaluation,and other methods are used to compare and analyze the fire risk of insulation composite layers under different pore size glass fiber mesh composite conditions,which is of great significance for the design of building external insulation systems.This thesis analyzes the pyrolysis characteristics of four materials based on a thermogravimetric analyzer,and concludes that polymer EPS,XPS,and PUR undergo three stages of thermal weight loss: dehydration stage,rapid weight loss stage,and stable heating stage.The thermal weight loss process of glass fiber mesh adds an impurity volatilization stage after the dehydration stage.Calculate the activation energy of four materials using the thermogravimetric method,with glass fiber mesh having the highest activation energy,followed by EPS and XPS,and PUR having the lowest activation energy.The influence of three types of glass fiber mesh apertures on the combustion characteristics of EPS,XPS,and PUR composite layers was measured using a cone calorimeter.Adding glass fiber mesh increased various indicator parameters during the combustion of the insulation layer,including ignition time,peak heat and flue gas release rate,time to reach the peak heat and flue gas release rate,total heat and flue gas release,initial release time of CO and CO2,and total CO2 generation.When combined with three types of glass fiber mesh apertures,The smaller the pore size of glass fiber mesh,the larger the values of these indicators.Based on FDS software,the combustion process of the exterior facade under the composite of glass fiber mesh with different apertures and insulation layers was simulated.It was found that the presence of glass fiber mesh itself to some extent extended the time for the insulation composite layer to be ignited and the time for the model’s most unfavorable escape point to reach the peak temperature.Under the composite working conditions of three different apertures of glass fiber mesh,the smaller the aperture,the later the peak temperature of the composite layer appeared;But fiberglass mesh will increase the temperature peak of the escape point,and the smaller the aperture,the greater the temperature peak generated during the combustion process.Based on experimental and simulation results,the Delphi AHP TOPSIS method is used to comprehensively evaluate the fire risk of insulation layers,and the comprehensive scores and ranking of insulation composite layers under different working conditions are obtained.For the three types of insulation layers,the order of fire risk influenced by the pore size of the glass fiber mesh is: PUR>EPS>XPS;The presence of glass fiber mesh will increase the fire risk of the insulation composite layer.Under the composite working conditions of 7mm,5mm,and 4mm aperture glass fiber mesh,the fire risk of EPS,XPS,and PUR composite layers increases with the decrease of the aperture of the glass fiber mesh.Figure [31] Table [28] Reference [87]...