Experimental Study Of The Effect Of Curing Temperature And Humidity On The Bonding Properties Of Non-expansion Coating Of Tunnel

With the rapid development of economy and the increasing of traffic,a large number of tunnels are used in the construction of roads in mountainous areas or hilly areas in order to improve the traffic speed.Fireproofing coating for tunnel is good for tunnel fire protection,that enhancing the fireproofing of the tunnel structure,and the construction is simple,economical and practical.At present,the study on the tunnel fireproofing coating mainly focuses on the formulation of the coating,little attention is paid to the bond strength between the tunnel fireproofing coating and the lining.To the poorbond strength of the coating,we selected non-expansion coating as the raw materials,considering the curing temperature,curing humidity and the drying degree of the lining,the experimental study on the bond performance between the coating and the lining was carried out.In addition,the influence of the amount of emulsion powder on the bonding performance was discussed.By a serious of system study and analysis,we made the following major achievements.(1)On the basis of summarizing the domestic and foreign literatures,the present study actuality and existing problems of coatings are analyzed.Finally,the study content and cases are proposed.(2)The influence of curing temperature,curing humidity and drying degree on the bond strength was analyzed by tensile test,the results show that the bond strength increases with the increase of curing humidity,the bond strength decreased with the increase of lining humidity.In addition,curing temperature has a greater impact on bond performance,curing temperature is too low or too high will lead to bond strength reduction.(3)The effect of admixture on the bond properties was discussed.Adding proper amount of emulsion powder can significantly improve the bond strength,and the bond strength is increased to 0.2MPa when the admixture content is 3%,the bond strength is 3 times higher than that of the no admixture.(4)The microstructure of the sample was observed after tensile testing to study between microstructure and bond strength by means of XRD and SEM.The results showed that the curing humidity was higher,the structure of hardened body was more dense and the lower the porosity after the hydration reaction,thus the bond strength was higher.The humidity of lining was large,the bond strength was smaller.