## 1 Introduction  
A bridge deck overlay is an important part of a long-span bridge. As a protective layer of deck deck, devaving directly affects driving safety and comfort, and it also significantly affects the service life of the whole bridge. Asphalt concrete is widely used in orthotropic steel deck overlay, because of its good driving comfort, fast construction speed, and easy maintenance. However, negative bending moment zones are formed at the supporting positions of cross beam, longitudinal rib, and main girder web because of small and uneven support stiffness of orthotropic deck. The negative moment results in a large tensile stress and even cracking in asphalt overlay [1]. In addition, the bonding performance between steel deck and asphalt overlay is poor, thus causing distress, such as jostle and upheaval [2]. Although epoxy asphalt concrete has good performance, it is expensive and highly sensitive to ambient conditions during construction. Moreover, the preparation and construction technology of epoxy asphalt concrete are complex. To solve these problems, since the 1990s, some scholars have tried to use a cementitious overlay to improve the stiffness of a steel bridge deck and its stress state [3]. In this study, engineered cementitious composite (ECC), a typical high-ductility cementitious composite (HDCC), was used as the overlay of an orthotropic steel deck bridge. [PERSON] first proposed the ECC design theory in the early 1990s [4]. ECC has remarkable strain-hardening and multicracking properties [5]. The ultimate tensile strain can be higher than 3%, which is approximately 300 times larger when compared to ordinary concrete, and the maximum crack width in a saturated state is usually below 100 \(\upmu\)m [6]. The stiffness of a bridge deck system can be improved by using ECC without increasing the thickness and weight of overlay because of the high modulus of ECC. Moreover, ECC has better temperature stability, water stability, and impermeability as compared to asphalt concrete, and it also has good self-healing performance and fatigue resistance. As for the interface connection for paving materials and bridge decks, cement-based overlay is often connected with steel deck by welding shear connectors [7, 8]. However, the welding process is inconvenient and might lead to stress concentration and fatigue problems for bridges. Moreover, the maintenance of these overlays is complex and tedious [9]. Wet-bonding technology is a good alternative for overcoming those disadvantages that are caused by welding connection. As one type of adhesive bonding, wet-bonding has the advantages of a large contact area, uniform stress distribution, improvement in the stiffness of overlay structure, and easy construction. Wet-bonding technology with epoxy adhesive has evolved as a new bonding technique. In 1995, [PERSON] [10] pioneered the use of wet bonding in composite beams, but delamination and peeling occurred in the interface of composite beams with wet-bonding. [PERSON] et al. [11] compared the effects of six types of interface modes through flexural tests of composite beams. The results showed that the wet-bonding effect of epoxy resin was slightly worse than that of dry-bonding. However, wet-bonding is regarded as the most practical interface mode when considering the actual construction of new composite structures. Many experimental studies were performed to evaluate the strength of wet-bonding interface; however, the findings are quite different among the studies [12, 13, 14, 15, 16]. The main reason for this difference is attributed to the different types of resins used in the studies. On the other hand, deck overlay is affected by various environmental factors in practical applications, and hostile environmental conditions might exist in some regions and seasons. For example, cold and dry winters characterize North China, while South China is characterized by hot and rainy summers. Therefore, freeze-thaw damage and hydrothermal aging should be considered in different climate regions [17].