| Lightweight composite bridge deck paving typically consists of STC(Super Toughness Concrete)layer,adhesive layer and SMA(Stone Mastic Asphalt)layer.Because the thickness of the SMA is relatively thin,resulting in a large strain in interlayer and SMA layer,coupled with the STC molding surface compaction,and its bite with SMA is insufficient,therefore,the interlayer bonding performance is one of the key technologies of the system;In addition,the lightweight composite bridge deck is mostly used for large-span steel bridges,usually located in important trunk roads,with much heavy load,therefore,the system design should take both the static performance and fatigue performance into account;Moreover,due to the large temperature difference between the environment in which the system is located,the performance under different temperature conditions should be researched.In this paper,two typical adhesive layer materials of hot-melt modified epoxy resin 202 and highelasticity and high-viscosity asphalt PG100 are selected to carry out the research of the interlayer performances between STC and SMA under both monotonic loading and cyclic loading at different temperatures.The main work and conclusions of the research are as follows:The STC-SMA interlayer static test and shear fatigue test under different temperature conditions have been carried out.The results show that temperature has a significant effect on the bonding performance of STC-SMA interlayer.With the increase of temperature,pull-off strength and interlayer shear strength of both 202 and PG100 are greatly reduced,and the fatigue lives of the two are also significantly reduced.Performance of the materials at high temperatures should be carefully considered during the design of light composite bridge decks;The difference in bonding performance of two different types of adhesive layers was compared,and the results showed that: under the same test conditions,pull-off strength,interlayer shear strength,interlayer stiffness,interlayer bonding energy and fatigue life of 202 are all significantly higher than PG100;especially at higher temperatures(45°C),the difference between the two is more prominent.The bonding performance and high temperature stability of 202 are significantly better than PG100,which is more suitable for bridges located in areas with heavier load and higher ambient temperature;The performance difference and correlation of interlayer performance with different failure modes are explored and results show that: pull-off strength and interlayer shear strength have obvious linear correlation,and the linear goodness of fit is as high as 0.936,indicating that these two indicators can both reflect the bonding performance though the failure modes are quite different;Shear testing is not convenient to operate on site,while pull-off test is easier to carry out and its results can reasonably and reliably evaluate the bonding performance between STC-SMA layers at the engineering site preliminarily;The potential relationship between several parameters obtained from monontonic test and the shear fatigue life is analyzed.The results show that the higher the parameters obtained,the longer the fatigue life.The correlation sequence is: Interlayer bonding energy IBE>interlayer shear strength ISS>shear stiffness IS,the goodness of fit are 0.984,0.945,0.779 respectively;IBE comprehensively considers the shear force of the adhesive layer and its ability to resist shear deformation,which characterizes the energy consumption of interlayer resisting the shearing process,and can be used as a reliable indicator for evaluating the performance of interlayers.The STC-SMA interlayer shear fatigue life prediction model is established,and the interlayer design method based on shear fatigue is proposed.The results show that the adhesive layer 202 can be used for heavy and extra-heavy traffic due to its excellent fatigue resistance;and PG100 asphalt can only be used for intermediate and light traffic.The research results provide a theoretical basis for improving the technical specifications of ultra-high performance lightweight composite bridge decks. |
