Experimental Study On Aging Performance Of Rubber Waterstop Under Different Conditions

In water conservancy projects,in order to adapt to the deformation of the foundation and the deformation caused by temperature changes,construction joints,settlement joints and deformation joints need to be left.Waterstops are then installed at these joints to prevent water seepage and leakage at the joints in the building.Environmental factors such as oxygen,ultraviolet rays,and temperature can affect the composition of rubber and damage the internal structure during use,which will cause the rubber to age.The direct manifestation is the decline in mechanical properties.As time goes on,this aging becomes more and more serious,which will eventually lead to the complete failure of the material and seriously endanger the safety of the building structure.Therefore,it is necessary to study the changes in the mechanical properties of rubber waterstops with the aging time and the aging mechanism.This subject is combined with the Tibet Lalo Water Conservancy Project.The local extreme environments of strong ultraviolet light and low temperature were simulated respectively,and the natural environment was used as a control to explore the ageing of rubber waterstops in these environments over time.The aging mechanism of the water stop is analyzed by a series of microscopic methods such as scanning electron microscope,energy spectrum and Fourier infrared spectroscopy.The following main conclusions were reached:(1)As the aging time increased,the tensile strength,elongation,tear strength,and compression set of the rubber waterstop gradually decreased,and the hardness gradually increased.Ultraviolet accelerated aging environment has the most adverse effect on the mechanical properties of rubber.In the ultraviolet accelerated aging environment,the mechanical properties decreased rapidly in the initial stage.In the natural environment,the decline was relatively rapid in the middle and late stages.In the low-temperature air and water environments,the medium-term strength changes were relatively slow,but the elongation decreased sharply.(2)The results of SEM showed that the surface of the rubber became yellow after accelerated aging under natural and ultraviolet light,and significant cracks and breakage occurred.With the increase of the aging time,the cracks gradually widened and deepened and penetrated each other.The poor adhesion between the rubber internal matrix and the admixture particles leads to a significant reduction in the mechanical properties of the material.In the low temperature environment,there were a large number of protrusions on the rubber surface,and holes or step-like delamination occurred in the late stage of aging,but the rubber still has good adhesion.(3)The results of EDS showed that with the increase of the aging time,the content of the element C in the surface of the rubber waterstop gradually decreased and the content of the element O gradually increased in each environment.In natural environment and ultraviolet accelerated aging environment,the content of C and O elements changed rapidly.In low temperature environment,the low temperature retarded the oxidation reaction on the rubber surface,which caused the change of C and O content to slow.(4)The results of FTIR showed that in natural environment and ultraviolet accelerated aging environment,the photo-oxygen reaction and the thermo-oxygen reaction occurred on the surface of the rubber waterstops,which caused carboncarbon double bonds to break and produced oxidation products such as aldehydes and ketones.In low temperature environment,the increase of the peak value of hydroxyl,carboxyl and other characteristic functional groups was small,and the oxidation was slow.