Material and Structure of Non-shaped Steel Expansion Joint Used in Pavement
In order to solve the problem of the frequent occurrence of pavement expansion joints,and to improve the maintenance and repair efficiency,as well as the utilization benefits,a study on the causes and solutions of expansion joints'diseases is carried out.Firstly,through the sufficient amount of on-site research and data analysis,the damage categories and causes of different parts of raad are grasped.Secondly,through the Maurer expansion joint structure analysis for design improvement and material study,a new type of non-shaped steel expansion joint structure is proposed,which is applied in a provincial highway test section in Hubei province.Then,through a compressive strength test,dynamic uniaxial compression test,high-temperature rutting test,water immersion Marshall test,low-temperature trabecular bending test and indirect tensile fatigue test,etc.,the performance of epoxy mortar mixture taken from the construction site is comprehensively tested.Finally,for the purpose of obtaining the joint width change rules with the temperature of daily cycle and annual cycle,the intermittent expansion joints width changes are monitored through the real-time displacement(joint width)monitoring system.The result shows that with the increase of service life,there are many diseases with different patterns,which reveal that there are many structural defects such as brittle and stiff joint features,drastic material transition,separate structural composition,and stress concentration.The strength of epoxy mortar mix in 24 h can reaches 70%of the strength at age of 28 d,which is characterized by early-strengthening properties,and its road performance is significantly better than that of the same-layer asphalt mixture.The reserved joint width is suitable,the joint width reaches the biggest value around 7:00 a.m.,and the lowest value is around 20:00 p.m.in autumn.Compared with the middle continuously reinforced concrete pavement(CRCP),the lateral CRCP presents lower temperature but higher joint width.April to May and October to November are the suitable construction periods with 40 mm implementation.The reservation should be increased in low temperature season,the reservation should be reduced in high temperature season,and the adjustment amount should be 10 mm.
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