| In order to research and develop a waterproof adhesive layer material for steel bridge decks with strong bonding performance,good durability and small external influences,this study added nano magnetic powder to the matrix asphalt to prepare nano magnetic powder modified asphalt.The asphalt modified by nanometer magnetic powder was magnetized to generate magnetic attraction between the waterproof adhesive layer and the steel plate,so as to comprehensively improve the bonding performance between the waterproof adhesive layer and the steel plate of the steel bridge deck pavement.In this research,the surface modification of nano-magnetic powder was carried out by chemical treatment method,and the best modification process was optimized through infrared spectroscopy;the asphalt preparation process was changed,and the dispersion of nano-magnetic powder in the asphalt was observed through scanning electron microscopy;three major index tests and dynamic shearing,Shear rheological test,low-temperature bending beam rheological test,low-temperature anti-cracking test and waterproof performance test were used to evaluate the basic and rheological properties of modified asphalt;The asphalt modified by nanometer magnetic powder was magnetized.and the performance before and after the magnetization was compared.The change of the bonding performance of the magnetically modified asphalt under the influence of temperature and impact load after magnetization is explored.The main research results show that:(1)The silane coupling agent KH-550 was selected,it has a good surface modification effect on the nano magnetic powder when the ultrasonic dispersion is 1.5h;The obtained nano magnetic powder has good dispersibility in the pitch when the shear rate is 6000r/min and the shear time is 20min in the preparation process of modified asphalt.Compared with base asphalt,nano-magnetic powder modified asphalt has better high temperature performance and antideformation ability,but it has an adverse effect on its low temperature performance,and the higher the content,the more obvious the effect.(2)Using the application rate of 0.8L/m2.1.1 L/m2 and 1.4L/m2 to conduct bar drawing inspection and shearing test on modified asphalt with nano-magnetic particle,the results show that the tensile strength and shearing strength of the application rate of 0.8L/m2 and 1.4L/m2 is less than 1.1 L/m2;the tensile strength and shearing strength of the modified asphalt with nanomagnetic particle first increase and then decrease with the increase of the nano magnetic particle.When the amount of magnetic particle is more than 30%,there will be a downward trend;according to the results of the asphalt steel wrapping test,the sheet steel asphalt bending test.and the waterproof performance test,the waterproof bonding layer of modified asphalt with nano-magnetic particle has better deformation compliance with the steel at low temperatures.Modified asphalt with different amount of nano magnetic particle has good waterproof performance under high pressure.(3)When the modified asphalt with nano magnetic particle has the best bonding performance after magnetization,the application rate is still 1.1 L/m2.Comparing the bonding performance of magnetic modified asphalt before and after magnetization,After magnetization,the tensile strength increase by 44.2%～113.3%and 10.4%～57.1%respectively at 25℃ and 60℃,and the shear strength rise by 39.2%～90.7%and 42.3%～66.1%respectively at 25℃ and 60℃.The tensile strength and shear strength of modified asphalt has good bonding performance when the amount of magnetic particle is at 30%,and the bonding strength decreases when the amount is less than or greater than 30%;after exploring the effect of external factors on the magnetic properties of magnetic modified asphalt,it proves that temperature changes have a greater impact on the bonding performance,while external impulsive load has less one. |
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