Study On Weather Resistance And In-Field Test Method For Silicone Sealant Of Glass Curtain Wall

Silicone sealant for glass curtain wall is subjected to various environmental ageing effects in service for the long term,which causes a serious decline in performance.The deterioration easily leads to leakage of water and air,reduction of thermal insulation performance,and causes glass panel to fall,thus seriously affects the social safety.In this dissertation,the ageing resistance and field detection techniques of silicone sealant were researched under various artificial accelerated ageing conditions.Firstly,this dissertation compared the changes of the properties of silicone weatherproof sealant before and after ageing under the conditions of temperature and humidity,UV,deionized water and salt solution,etc.The synergistic effect of temperature and humidity was the main factor to reduce the performance of sealant by studying the shore hardness and tensile strength of sealant.On this basis,the ageing resistance of structural silicone sealant at extreme temperature and the tensile failure modes of the samples were further explored,and the failure causes were analyzed by the finite element simulation and the non-contact strain measurement.The results showed that the stress and strain at the interface is larger during the tensile process,and the ageing of adhesive properties at the interface are more obvious in the high temperature and high humidity environment.As a result,the failure mode of specimen changed from cohesive failure to interface failure.Meanwhile,in view of the strong deformability of sealant,the original fixture was improved to simplify the operation progress and improve the accuracy of the measurement results.Secondly,the stress fatigue of structural silicone sealant caused by the long-term effect of natural wind on glass curtain wall had been neglected in existing researches.In this dissertation,the tension pressure of silicone sealant due to the long-term negative wind during service was calculated according to the relevant national standards and actual conditions.It was found that the continuous cyclic action of natural wind will cause the irreversible damage to the structural silicone sealant interiorly and lead to deterioration of bond property via the artificial accelerated fatigue test.Based on the theoretical research on the weather resistance of silicone sealant,this dissertation developed the in-filed test method and evaluation technology of silicone sealant properties.The pin method was invented independently,which could be used to evaluate the sealing and adhesive properties of silicone sealant conveniently.Meanwhile,the testing principle of Shore A Durometer was intensively studied for the shore hardness is the sole index of silicone sealant which can be obtained fleetly in the field.Based on the comprehensive application of shore hardness and load-displacement curve,combined with the formula of the nanoindentation method,the dissertation derived the formula for calculating elasticity modulus by shore hardness,and made it possible to master other performance indicators by measuring the shore hardness alone.