Experimental Research On Durability Of SBS Modified Bituminous Sheet Materials

With the use of SBS modified bituminous sheet materials,its durability problem are getting more and more attention,the influence of waterproof material durability on the service life of buildings can not be ignored.When SBS modified bituminous sheet materials are used as the roof waterproof material without protective layer,it's going to undergo natural aging;When SBS modified bituminous sheet materials are used as the underground waterproof material or in cold regions,it's going to undergo soaking aging or freezing-thawing cycles aging.This paper studies natural aging,soaking aging and freezing-thawing cycles aging of SBS sheet materials by testing the parameters changes of tensile properties,heat resistance and low temperature flexibility of two kinds of polyester base materials SBS sheet materials.The results show that the influence of natural aging on the SBS sheet materials which have same type and different formula is basically the same,but the influence degree is different.During natural aging process,the upper surface of the bituminous cover layer will become hard and powder in the ultraviolet light condition,cracks caused by local shrinkage and evolved into fractures gradually.In the early natural aging,SBS sheet materials have experienced three processes,namely,the internal moisture content increases,th internal moisture content decreases(dry after soaking)and the freezing-thawing cycles,these three processes directly affect performance of polyester base materials.the influence of soaking aging and freezing-thawing cycles aging on the SBS sheet materials which have same type and different formula is basically the same,but the influence degree is different.Soaking aging has a significant effect on the performance of polyester base materials,especially in the early stage of soaking aging.In soaking environment,water will enter the inner of SBS sheet materials and reacts with dip coating materials and polyester base materials,which causing a permanent inctease in thickness and weight.The influence of soaking aging and freezing-thawing cycles aging on the tensile force is very regular,after adding trend line to the date of tensile force,R2 are close to 1,this shows that tensile force can be predicted by mathematical method.In the material selection,the waterproof project which Waterproof layer for long-term exposure to the outside,should pay more attention to the performance of asphalt coating,choose good quality of dip coating material of SBS modified bituminous sheet materials to prevent the failure of asphalt coating due to ultraviolet radiation and other reasons and lose the protection of polyester base materials and waterproof effect;The underground waterproof project or the waterproof project which have the function of freezing and thawing,should choose good quality of polyester base materials of SBS modified bituminous sheet materials to prevent the lack of durability of polyester base materials,first to reach the service life,finally,sheet materials fracture due to basic deformation and other factors,lose waterproof effect.