| The PC concrete building has many advantages,such as improving quality,shortening time,saving energy,reducing consumption,cleaning production and so on;It is one of the main directions of future architecture development.Structural sealants are required to be bonded between the assembled concrete plates,but as the use of time increases,structural sealants can deteriorate the mechanical properties such as bond strength and deformation properties,it affects the service life of the assembly building,therefore,it is necessary to study the aging properties of sealant;It is helpful to predict the life of sealant.Compared with other sealants,silicone sealant is better at high temperature,water resistance and weather ability than other sealants,therefore,the durability of silicone sealant is studied.The usual method of study is to carry out a natural climate exposure test(also known as outdoor weather resistance test),the comprehensive effect of climate factors such as sunlight,temperature,moisture and so on,evaluation of the weather ability of structural sealant by measuring the change of its properties.To speed up the speed of aging,in this paper,the accelerated test of indoor artificial aging is carried out.In this paper,silicone structural sealant adhesive specimens is selected(bonded base material is concrete),the experiment is divided into five stages,the first stage is test the national standard GB 16776-2005,"building silicone structural sealant" national standard revision process of the validation.Test the tensile bond and several technical specifications related to it,the influence of heat,water,light/heat/water and other factors on the tensile bond strength,the elongation at maximum stress and the elongation at break are discussed.In the second stage,the main factors affecting the life span of silicone sealant for assembly building are carried out,but the experiment of factor aging is carried out,analyzing the aging mechanism of structural adhesive under various factors,evaluating the sensitivity of the factors affecting the durability of structural adhesives;Fitting the data of UV and thermal aging,regressive equation.The third stage is test comprehensive aging factors,analyzing the aging mechanism,and compared with the previous results of single factor aging.In the forth stage,analyzing the effect of sealant movement in the actual use of structural adhesive.confirming the width and depth of construction glue seam.The fifth stage is analyzing the problems that may be encountered in the construction and the solutions are put forward.The emphasis of this paper is on the synergistic aging of single factor and multiple factors for the silicone sealant used in the assembly building,analyzing and comparing the data of the aging experiments,the order of the aging factors of silicone structural adhesive for assembly building was obtained.The analysis was carried out by the method of variation coefficient,it is because it takes into account the fluctuation of the properties of the bonded specimen under different aging time.And as the most common aging factor for silicone sealants used in assembled buildings,simulating the regression equation of UV and thermal aging,the correlation coefficient of the equation is good.The experiment proves that,the senescence of the silicone structural sealant used for assembly building is different for different factors.The aging mechanism of each aging factor is different.The comparison and discussion are carried out in this paper. |
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