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Because of the problem of local scour caused by the change of the flow structure caused by the water-resistance of the column bridge pier, the theoretical analysis, and indoor water tank test were used to study the effect of installing a new anti-scouring device in front of the bridge pier on the local scour reduction effect; the influence of the main design parameters such as the height of the protective device, the angle of the protective device and the distance from the protective device to the bridge pier on the local scour of the bridge pier was selected, and the optimal parameter design combination was selected. The test results show that: under the same water flow conditions, the maximum scour depth reduction rate of the measuring point under the protection of the protective device is 48.4% to 74.2% compared with the unprotected scour; the reduction rate of the bridge pier is relative to the relative height of the device and the device equivalent. The angle and the distance between the device and the bridge pier are related, and the shock reduction rate decreases with the increase of the flow intensity. In the test range, the ratio of the device height to the water depth is 2/3, the device angle is 60 °, and the distance from the bridge pier is 3. When the diameter of the pier is doubled, the effect of reducing the impact on the pier is the best.

In order to reduce the local scour before the antiscour device of piers, this paper proposed an improvement on a "V-type" device. That was to say, wing plates were set on the surface of the "V-type" device to enhance the diversion and reduce the local scour. To explore the protection effect of the modified device, the inclination angles of the wing plates were set to three angles, and the scour characteristics around the device were studied through the flume scour test and numerical simulation test. The results showed that the wing plates can reduce the impact force of the diving flow which was at the front end of the protective device. Besides, they could also disturb the flow around both sides of the device and weaken its sediment carrying capacity. Thus, the local scour around the device was effectively reduced. Especially, when the wing plates were 30°, the performance of reducing the local scour was the best. [ABSTRACT FROM AUTHOR]

This study investigates the resilient modulus of vertical vibration compacted cement-stabilized macadam (CSM). The reliability of the vertical vibration compaction method (VVCM) for CSM was verified. Then the influences of four factors on the resilient modulus were studied and a resilient modulus prediction equation was proposed. Subsequently, the influences of aggregate type, cement dosage, and gradation on the initial and ultimate resilient moduli were studied. Results show that compared to the quasi-static-compaction method, the VVCM has a smaller influence on the optimum water content and aggregate gradation, and VVCM specimens have a higher correlation with the on-site cores. The increase of cement dosages and curing times can improve the resilient modulus and the proposed prediction equation can accurately predict the resilient modulus growth of the CSM. When the cement dosage and aggregate gradation are identical, the initial and ultimate resilient moduli of the cement-stabilized limestone are the largest, followed by the cement-stabilized granite and sandstone. The initial and ultimate resilient moduli of the CSM increase linearly as the cement dosage increases. Moreover, the skeleton-dense gradation helps to improve the initial and ultimate resilient moduli of the CSM. This study provides guidance for the design and construction of a CSM base. [ABSTRACT FROM AUTHOR]

To reduce asphalt pavement temperature and improve its anti-rutting performance in summer, thermally resistant friction course (referred to as TRFC-13), heat-reflective coating (referred to as HRC) and thermally resistant and heat-reflective coating integrated pavement (referred to as TR-HRC) were developed, and their cooling effect, anti-rutting performance and durability were evaluated. In addition, machine-made sands were applied to improve the anti-skid performance of the coating. The results show that compared with ordinary SMA-13 samples, the surface temperature of the TRFC-13, HRC and TR-HRC samples decreased by approximately 6.8°C, 11.2°C and 13.2°C, respectively. At the air temperature of approximately 40°C, the field road surface temperature of the TRFC-13, HRC and TR-HRC decreased by approximately 7.4°C, 12.2°C and 14.0°C, respectively. The higher the air temperature is, the better the anti-rutting performances of these three kinds of pavement. At the air temperature of 39°C, the dynamic stability of the TRFC-13, HRC and TR-HRC is 1.56 times, 1.86 times and 1.88 times that of the ordinary SMA-13, respectively. The results also show that HRC has a strong abrasion resistance and that spreading 40 wt% of machine-made sands can ensure the coatings achieve the best British Pendulum Number, without influencing its cooling performance. [ABSTRACT FROM AUTHOR]

The treatment result of water-based epoxy resin emulsion upon different segregation conditions was studied by using AC-20 asphalt specimens. The study shows that the treatment materials are increasing with increase of segregation degree. The water permeability coefficient decrease significantly after treating, and it decreases when the water-based epoxy resin emulsion content increase. Also the times of brush can decrease the water-based epoxy resin emulsion content effectively. Because the treatment materials just treat the surface of specimen, play a sealing water effect and fill little inside, the overall void ratio is not significantly reduced. [ABSTRACT FROM AUTHOR]

Volumetric properties, such as volume of air voids (VV), voids filled with asphalt (VFA), and voids in mineral aggregate (VMA), strongly influence the performance of asphalt mixtures. This paper analyzes the influence of volumetric properties on the mechanical properties of the ATB-30 asphalt mixture which molds using vertical vibration compaction method (VVCM). Suggested values of volumetric properties were proposed based on the optimization of mechanical properties. Additionally, the proposed design was evaluated based on its performance in practice. Results show a 92% testing accuracy of the mechanical properties of VVCM specimens. This accuracy reveals that the vibration molding is compatible with the mechanism of the roller. High consistency was observed between the mechanical properties of the ATB-30 asphalt mixture and VV, VFA. However, the correlation between mechanical properties and VMA was poor. Hence, the suggested values of VV and VFA in the ATB-30 asphalt mixture are 2.8%–4.0% and 64%–74%, respectively, and VMA is only used as a reference with a value of at least 10.5%. Compared with the Marshall Compaction method (MCM), the Marshall stability, dynamic stability, splitting strength, and tensile strength of the ATB-30 asphalt mixture increased by 54.4%, 39.1%, 54.8%, and 53.7%, respectively, when using the design-suggested values of the VVCM design. The water stability of the asphalt mixture also improved. [ABSTRACT FROM AUTHOR]