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Rejuvenating the reclaimed asphalt pavement by crumb rubber modified binder for recycling in new pavements arouses a great interest as a sustainable paving technology that uses waste to recycle waste and hinders resource depletion. By investigating rheological and adhesion/cohesion characteristics of the asphalt binder, this study aims to divine optimal dosages of reclaimed asphalt and crumb rubber that enhance the overall performance of the binder without undermining any feature. Thirty binders produced from two types of virgin binder, two sources of reclaimed asphalt, three dosages of reclaimed asphalt, and two dosages of crumb rubber were prepared and tested. Bonding, rheological, and physiochemical characteristics of binders were investigated using pull-off test, dynamic shear rheometer, and Fourier transformed infrared spectroscopy. The results show that mixing reclaimed asphalt with rubberized asphalt greatly enhances the cohesion strength, rutting resistance, creep resistance, and colloid homogeneity. However, certain reclaimed asphalt and crumb rubber dosages undermine the fatigue cracking resistance. The physiochemical investigation revealed that the crumb rubber chains intensively swell and disintegrate simultaneously during mixing with virgin binder and further mixing with reclaimed asphalt. Through correlation analysis, it was emphasized that the improvement of cohesion strength and rheological characteristics is ascribed to the physiochemical changes caused by crumb rubber interaction and reclaimed asphalt addition. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Optical fiber sensors have better corrosion, electromagnetic interference resistance and signal-to-noise ratio. • Optical fiber sensors can measure the strain, temperature and pressure information of pavement in real time. • The applications of optical fiber sensors in pavement are more and more extensive. Optical fiber sensor (OFS) is a commonly used tool to monitor the serviceability and integrity of pavements. The earliest application of optical fiber sensors in the road can be traced back to the early 21st century, and development of this technique has been extensively studied after that. In view of the increasing demand for pavement nondestructive testing and the rapid development of optical fiber sensor technology, this work summarizes the optical fiber sensors commonly used in road engineering and the classification methodologies. After that, the basic principle of fiber Bragg grating (FBG) sensor and the application of this sensor in the pavement were discussed. Finally, the principle and application of distributed optical fiber sensors (DOFS) in the pavement were included as well. Overall, this review found that FBG sensors can accurately measure and monitor road strain, temperature, pressure and WIM measurement by employing analytical-based methods. Distributed optical fiber sensors can measure pavement crack width, identify the void under the concrete slab, and obtain vehicle load (load size, load moving speed, axle type) and other data. Currently, it has been proved that the installation of the installation of fiber optic sensors on the road surface is an effective method to monitor the integrity of the road structure under traffic, but further tests in real traffic environment to further improve the survival rate of fiber optic sensors and evaluate the accuracy of the measured results are still needed. [ABSTRACT FROM AUTHOR]

Considering the enormous amounts of virgin materials consumed in road construction and rehabilitation, recycling reclaimed asphalt pavement has aroused great interest recently. Among different modifiers, crumb rubber is a waste material that significantly enhances different characteristics of the asphalt binder. This study investigates the bonding strength of asphalt mastic of reclaimed asphalt binder modified by crumb rubber-modified binder. The study also attempts to model the mastic bonding strength and understand its mechanism. Thirty binders with different percentages of crumb rubber and reclaimed asphalt were mixed with two filler types to produce the asphalt mastics. Moreover, the two phases of the binder colloid, gel and liquid phases, created by crumb rubber modification, were separated to evaluate the crumb rubber interaction and its impact on mastic bonding. The pull-off test was used to evaluate the bonding strength of asphalt mastics and binders, while dynamic shear rheometer and Fourier-transformed infrared spectroscopy were used to evaluate the physiochemical and rheological characteristics of the asphalt binders. The results show that crumb rubber and reclaimed asphalt modifications greatly strengthen the mastic bonding. The accretion of carbonyl groups due to the reclaimed asphalt addition and withdrawal of light components due to the crumb rubber interaction improves the stiffness of the liquid phase binder, which is strongly correlated to the mastic bonding strength. Furthermore, despite its role in strengthening the binder stiffness, the crumb rubber particles as fillers no longer affect the mastic bonding, where this role is undermined by the mineral fillers. [Display omitted] • Crumb rubber and reclaimed asphalt pavement binder modifications enhance the mastic bonding strength. • Mastic bond is highly correlated to the binder bond strength. • Crumb rubber interaction with asphalt binder strengthens mastic bond. • Mastic bond increases by increasing the carbonyl intensity. • The incorporation of mineral filler undermines the crumb rubber impact as filler. [ABSTRACT FROM AUTHOR]

Incorporating reclaimed asphalt pavement (RAP) increases concern about long-term fatigue and cracking resistance of the resultant mixture due to the presence of an aged binder. Using a rejuvenator is one of the most promising methods to prolong the aging time for initial cracking and allow the inclusion of higher RAP content. Many discrepancies exist in the literature about rejuvenators' effectiveness in improving the fatigue performance of RAP binder and mixture. These ambiguous and contradictory findings are attributed to using different rejuvenator types and dosages, RAP sources and percentages, binders and mixture fatigue testing approaches. This paper comprehensively reviews and investigates the existing literature to fully understand the rejuvenation mechanism and its impact on the fatigue and cracking resistance of RAP binder and mixture using the most available tests and indicators. In addition, a rigorous laboratory study is carried out to determine the sensitivity of indicators to mix composition and variability. It is concluded that the inclusion of rejuvenators into RAP binders and mixtures may not improve their fatigue and cracking performance to the same level as virgin materials. But by utilizing polymer modification, the bonding between materials increases significantly, which results in better fatigue performance of rejuvenated RAP materials. Despite the positive impact of rejuvenators on RAP mixture fatigue performance, a comparison of different tests results does not offer a consistent indicator for determining fatigue resistance. Hence, it is recommended that the future research should be carried out with reasonable test methods, more complicated analytical techniques, service life characterization models, and climate identical test conditions, to clarify the durability index. Also, a complete evaluation of field performance utilizing RAP and rejuvenator is valuable. [ABSTRACT FROM AUTHOR]

On the basis of the structural characteristics of subway stations, structural inertial force can be simplified as multiple concentrated force acting on the member connecting node by using equivalent inertial force method of seismic calculation in soft site, and then internal forces of the structure will be analyzed. According to the principle that the maximum bending moment values of equivalent inertial force method and dynamic time-history analysis method are equal and the location is the same, the value of equivalent inertial force is determined, and the shear and axial force are ensured by introducing correction factor. The result shows that the calculation results of equivalent inertial force method are accurate and reliable. It can meet the design requirements and improve computational efficiency. [ABSTRACT FROM AUTHOR]