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The occurrence of cracking, loosening, and other distresses in asphalt pavements is closely related to the failure of asphalt–aggregate adhesion. Studying the effect of asphalt film thickness on asphalt–aggregate adhesion can facilitate an understanding of the mechanism of disease in asphalt pavements. To study the impact of asphalt film thickness on asphalt–aggregate adhesion, this study tested and evaluated the adhesion between asphalt and aggregates at different asphalt film thicknesses from a macromechanical perspective via pullout tests. In addition, based on the surface energy theory, the effects of different film thicknesses on the adhesion of asphalt–aggregate were analyzed from a surface mechanics perspective. Further, the aggregates were subjected to surface property testing to further investigate the differences between the surface mechanics and the macromechanics results. The results showed that for an asphalt film thickness of 400 μm, the failure energy density (FED) and cohesive work (WA) of the asphalt exhibited the same trend, and certain properties of asphalt influenced its adhesion to the aggregate. For an asphalt film thickness of 25 μm, the FED and the asphalt adhesion work (Was) exhibited the same trend, and the combined effect of the asphalt and slag properties influenced the adhesion of asphalt to steel slag. Moreover, with decreasing asphalt film thickness, the adhesion between asphalt and aggregates was reduced owing to the influencing factors of the asphalt, which can effectively reduce the influence of the aging effect on adhesion. [ABSTRACT FROM AUTHOR]

In practical engineering, it is common to offset the drainage system axis to avoid conflicts with beams and columns. However, such an offset could significantly affect the system's discharge capacity and drainage safety, leading to a prominent positive pressure above the offset floor. To address this issue, we propose optimizing the system by changing the elbow shapes at the offset position. In our study, we conducted comparative experiments on three elbow shapes, namely, a normal 90° elbow, double 45° elbow, and large curvature elbow, in two experimental systems. Pressure fluctuation and water seal losses were used as experimental parameters to determine the maximum discharge capacity in accordance with the Standard for Capacity Test of Vertical Pipe of the Domestic Residential Drainage System. Our experimental results show that replacing the 90° elbow with the double 45° elbow slightly reduces positive pressure. On the other hand, using the large curvature elbow effectively increases the drainage flow and reduces the positive pressure caused by the upper floor bias. Furthermore, we employed computational fluid dynamics (CFD) software to simulate the flow of water and air in the system, demonstrating the benefits of increasing the elbow at the connecting position. [ABSTRACT FROM AUTHOR]

To better understand the shear stress distribution in rock-cemented discontinuities, such as bedding planes and mineral-filled natural fractures (NFs), subjected to direct shear, an analytical solution for shear stress was first derived on the basis of the compression and bending theories of materials. The shear stresses obtained using the analytical solution for different conditions were then verified by the numerical simulation method. Finally, the main factors that influence the shear stress distribution in cemented discontinuities were explored using the analytical solution and numerical simulation methods. The results showed that the internal moment generated by shear forces significantly affects the shear stress distribution in a cemented NF. The analytical solution which considers the internal moment can accurately predict the shear stress distribution in most cases. The shear and normal stresses are both concentrated near the ends of cemented NF; however, they are comparatively uniform in the central portion. The shear stress concentration decreases with the increasing width of cemented NF, whereas it increases with Young's modulus of cemented NF. The nonuniformity in shear stress decreases with the specimen height, and only when the specimen height is equal to the specimen length, the error produced by the analytical solution attains a minimum. The tractions on the loading surfaces are significantly nonuniform, and the nonuniform tractions are to balance the bending moment created by shear forces. Moreover, the shear box can dramatically influence the shear stress distribution in cemented NF. Uniform normal and shear displacements which represent the normal and shear forces loaded via a rigid shear box should be used for the boundary conditions. The findings in this study can provide a theoretical foundation for the evaluation of deformation properties and shear strength of intact rocks, rock interfaces, bedding planes, or mineral-filled NFs subjected to direct shear. [ABSTRACT FROM AUTHOR]