## 1 Introduction  
At present, most bridge deck pavement structures use a \"concrete slab + asphalt concrete\" pavement system. Cement concrete pavement is initially poured, and asphalt concrete is then paved over the surface of the cement concrete pavement to form a rigid-flexible composite structure [1]. The waterproof cohesive layer ensures the bridge remains waterproof, and the rigid-flexible structure layer is bonded together. As an important part of the bridge deck pavement structure, improperly setting the waterproof cohesive layer will result in an insufficient interlayer bonding force or shear strength, ultimately damaging the overall pavement structure [2]. Therefore, it is particularly important to study the shear fatigue characteristics of the waterproof cohesive layer. Many scholars have focused their research on the deck pavement's construction and the waterproof material [3; 4; 5; 6]. Some scholars have studied the effect of construction temperature on interlayer cohesion. For example, results from a TRRL [7] test in Britain showed that using an asphalt mixture in paving will damage the waterproof cohesive layer, thus affecting affects its performance. [PERSON] et al. [8] showed that the shear strength of the waterproof cohesive layer decreases as the temperature increases. [PERSON] et al. [9] used grey correlation to determine correlations among various factors that influence the shear strength of the waterproof cohesive layer. Some scholars have developed new waterproof cohesive layer materials to improve the shear strength of bridge deck pavement. For example, [PERSON] et al. [10] improved the cohesive force of a waterproof material by incorporating a latex modifier similar to the emulsion and proposed an optimum coating thickness of 0.7-1 mm. [PERSON] et al. [11] developed a macromolecule polymer bitumen waterproof cohesive layer that is suitable for hot, humid regions. [PERSON] [12] developed a new epoxy-modified asphalt waterproof adhesive material with bond strength reaching 0.6 MPa, which greatly increased the bonding strength of the bridge deck waterproof cohesive layer. [PERSON] et al. [13] developed a high-performance polymer bridge deck waterproof adhesive material with 0.5 MPa shear strength at 25 \({}^{\circ}\)C and 0.0885 MPa at 60 \({}^{\circ}\)C. Other scholars studied the shear resistance and fatigue life of the waterproof cohesive layer. The research of [PERSON] et al. [14] showed that the primary factor determining the shear strength is the interaction between the rubber asphalt and the concrete surface. [PERSON] et al. [15] used a French pavement design procedure to analyze the stress on the pavement between different layers and found that insufficient contact between layers may reduce the service life to 65-70% of the design life. In summary, although many scholars have studied the waterproof cohesive layer with different test methods, evaluation indicators, and standards, there are still some shortcomings [16; 17; 18; 19]. For example, the interlayer construction method and material are rarely considered together, and the development of new materials is costly and difficult to apply. There is no unified standard regarding the content of relevant materials used in the waterproof cohesive layer. The initial stage of fatigue damage in the waterproof cohesive layer is difficult to observe, and research on shear fatigue damage to a waterproof cohesive layer in a bridge deck is lacking. The common waterproof synchronous gravel cohesive layer, shear strength of different disposal schemes for a cement slab, bonding materials, and different combinations of spreading schemes were examined and compared in this study. The optimum material composition (which corresponds to the maximum shear strength in different test schemes.) of the waterproof cohesive layer for a bridge deck is presented based on comprehensive consideration of various interlayer construction methods and materials.