Study On Environmental Adaptability And Fire Performance Of Non-Expanded Tun-Nel Fire Retardant Coatings

The construction level and tunnel mileage of China's long road tunnels have shown a leap-forward development.Tunnel fires frequently occur and the losses are large.At present,passive fire prevention mainly uses tunnel fireproof coatings.As the same time undertake fire prevention,anti-shedding with the ability to operate during a very critical role,but the tunnel many diseases,conditions resulting in poor paint coming off injuries,study environmental adaptability of tunnel fire retardant coating is necessary.This paper selects three environmental factors?water immersion,acid corrosion,dry and wet cycle damage?that affect shedding,conducts macroscopic quantitative analysis and microscopic mechanism research,and compares them by adding modified binder?dispersible latex powder,waterborne acrylic emulsion?.The bonding performance of the coating was calculated.The fire resistance of the coating was numerically calculated,and the distribution law of the temperature field of the lining under high temperature environment was analyzed.The following are the results of various environmental factors and fire performance numerical calculations:1.Through the water immersion test,the bond strength increases with the increase of the immersion period.After XRD diffraction analysis,it is found that the water plays a major role in the early curing process of the coating,and promotes the hydration of the silicate cementitious material in the coating.And the redispersible latex powder can significantly enhance the bonding stress of the coating to the substrate.2.The laboratory simulated different soaking time experiments with different acid strength?ie different pH?and the same acid strength.After XRD diffraction analysis and microstructure observation of Leica material microscope,the stronger the acidity?the lower the pH value?,the surface formed on the coating.The higher the content of gypsum product?CaSO₄?,the more severe the change of coating appearance and the greater the decrease of bond strength.However,the experiment of different corrosion time showed a slight decrease in the bond strength at the initial stage of infiltration,and the consumption of acid H⁺in the middle stage.The combination of coating and base layer shows an increasing trend.3.Simulating the damage degradation test of the coating under the action of dry and wet cycles.After the equal increase of the number of cycles,the mass loss rate of the coating is gradually increased,and the bonding stress between the coating and the substrate is continuously reduced,and the admixture is passed through.The addition of both can improve the dry and wet resistance,and the latex powder has better environmental adaptability than the aqueous acrylic.4.Orthogonal experiment was carried out to study the significant relationship among water,acid solution and dry-wet cycle.The SPSS analysis of variance showed that the bond strength of moisture to fireproof coating increased with time,and corroded with acid solution concentration.the bond strength is gradually reduced,while the wet process is not obvious role in the three,i.e.,the influence of moisture>acid corrosion>wet-dry cycle.5.With the finite element software ANSYS,the performance of the insulation of the fire-retardant coating was analyzed and the temperature change of each node of the cross-section of the lining was studied.Due to the effect of heat convection,the top temperature of the arch was the highest,and the temperature was second.The thickness direction of the lining is gradually decreasing,and due to the low thermal conductivity of the fireproof coating,the temperature gradient is lowered more quickly,and the concrete lining is effectively protected.