Research On Preparation And Properties Of Bridge Seamless Expansion Joints Material

Seamless expansion joints used as a type of bridge expansion joints, also known as asphalt plug joints in foreign, have caused extensive attention because of many unique advantages whatever home and abroad. But there are some defects, including rut deformation at high temperature and crack easy at low temperature, telescopic displacement insufficient, and so on. In order to improve the material defects of the existing seamless expansion joints in this paper, on the one hand, the binder of expansion joints material was modified by the addition of rubber powder into SBS modified asphalt, on the other hand, rubber granule was used as aggregate to partly replace mineral aggregate, high performance seamless expansion joints materials can be synthesized by the modification of rubber powder and granule, as well as the various properties of expansion joints materials were researched.In this paper, the conventional three index test and dynamic shear rheological tests were used to evaluate and compared the various performance of the binder of expansion joints material. The test results show that, compared with SBS asphalt, rubber powder modification can significantly improve high temperature stability of asphalt, the anti-rutting deformation capacity, and reduce temperature sensitivity of asphalt.High temperature stability and low temperature crack properties of the expansion joints materials in different alternative ratio of rubber granule were studied in laboratory. The test results show that with the increase of the proportion of rubber particles alternative, dynamic stability of material is decreasing. When the alternative ratio is more than9.2vol%, the decline of the stability is very obvious, but when the ratio reach16.3vol%(i.e. the mine materials, less than4.75mm, are all replaced), the dynamic stability are still more than1000/mm. With the increase of the proportion of rubber particles alternative, flexural strain of the expansion joints material increases gradually. When the alternative ratio is12.6vol%, the flexural strain is more than10000μm/m, the low temperature flexibility is very superior. Rubber powder modification does raise high temperature stability and the low temperature crack resistance of the expansion joints of material energy.Dynamic modulus and viscoelastic properties of the expansion joints materials were researched. The results show that dynamic modulus and phase angle of the materials has obvious temperature and frequency dependence. With the increase of the alternative proportion of the rubber particles, dynamic modulus gradually reduced. The time-temperature equivalence principle was used to fit out master curve of the expansion joint materials. It can be observed the curve of the dynamic modulus descend and become gentle with the increased alternative amount of rubber particles, the phenomenon indicate that the addition of rubber particles reduces the temperature sensitivity of the material. High temperature dynamic creep test results show that the reasonable rubber particles replacement can reduce the permanent deformation amount of material. Low temperature stress relaxation test results show that when the rubber particles alternative more than9.2vol%, relaxation ability appear a turning point, improved effect of relaxation is more obvious.