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In order to solve the problems of difficult compaction and poor durability of ultrathin overlays, the performance of easy-compaction and high-durability (ECHD) modified asphalt and mixtures were studied. Taking matrix asphalt and SBS modified asphalt as the control group, the high- and low-temperature rheological properties of the asphalt were analysed by MSCR and BBR. The asphalt samples were observed and analysed by fluorescence microscope and infrared spectrometer, and the road performance, compaction performance and surface functional durability of the asphalt mixture were tested. The results show that the ECHD asphalt has the best high- and low-temperature properties. The modifier particles are uniformly dispersed in the asphalt, which can form a dense network structure and a stable system. The ECHD asphalt mixture has good low temperature and water stability, and the high-temperature stability is slightly lower than that of the SBS-modified asphalt mixture, but meets the requirements of the specification. It has the smallest compaction energy index CEI, and the largest compaction rate K. Before and after wearing 30,000 times, the asphalt mixture has the best wear resistance and surface texture, and the surface functional durability is the best. This paper provides a reference for material selection of ultrathin overlays. [ABSTRACT FROM AUTHOR]

Bio-shell is a renewable bio-waste resource being used to develop sustainable and environmentally friendly pavement materials. In this study, bio-shell was mixed with asphalt to prepare bio-shell-modified asphalt. The modified asphalt was divided into four groups with 0%, 5%, 10% and 15% of waste bio-shells. The morphology of the bio-shell was investigated by scanning electron microscopy tests. Penetration, softening point, and ductility tests were performed to analyse the basic physical properties of bio-shell asphalt. Dynamic shear rheometer and bending beam rheometer were used to high and low-temperature rheological properties of the bio-shell-modified asphalt. Fourier transform infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy were used to analyse the atomic distribution and relative content of bio-shell-modified asphalt and reveal the modification mechanism. Atomic force microscopy was employed to observe the nano-microscopic morphology of the bio-shell-modified asphalt, and to analyse the changes of the bee structures in the asphalt. The results showed that the high-temperature rheology of 15% bio-shell asphalt was the best. The rutting factors of the asphalt increased by 38%, 43%, 45%, 50%, 55% and 63% at temperatures of 40°C, 46°C, 52°C, 58°C, 64°C and 70°C, respectively, compared to the matrix asphalt. [ABSTRACT FROM AUTHOR]

Pavement performance prediction is a crucial issue in big data maintenance. This paper develops a hybrid grey relation analysis (GRA) and support vector machine regression (SVR) technique to predict pavement performance. The prediction model can solve the shortcomings of the traditional model including a single consideration factor, a short prediction period, and easy overfitting. GAR is employed in selecting the main factors affecting the performance of asphalt pavement. The SVR is performed to predict the performance. Finally, the data collected from the weather station installed on Guangyun Expressway were adopted to verify the validity of the GRA-SVR model. Meanwhile, the contrast with the grey model (GM (1, 1)), genetic algorithm optimization BP [[parms resize(1), pos(50,50), size(200,200), bgcol(156)]]081%, -0.823%, 1.270%, and -4.569%, respectively. The study concluded that the nonlinear and multivariate prediction model established by GRA-SVR has higher precision and operability, which can be used in long-period pavement performance prediction., 1. Introduction Big data maintenance is a central issue in highway management. Highway maintenance mileage accounted for 97.7% of the mileage of traffic in China by the end of 2018. [...]

The bonding strength between the overlays of an airport asphalt pavement directly affects its service life. In this study, a finite element model of asphalt overlay on airport pavement of Juba Airport in South Sudan was established, and the elastic modulus of overlay, thickness of overlay, running state of aircraft, variation trend of interlayer shear stress under the action of load and temperature were obtained. The AHP-entropy method was used to calculate the combined weight of each influencing factor. The climate in hot and humid areas was further zoned, and a comprehensive classification of airport asphalt pavement overlay between hot and humid tropics was obtained. Four interlayer treatment measures (asphalt precoating, two oils and one aggregate, geotextile, and geogrid) and three interlayer materials (SBS-modified asphalt, ordinary hot asphalt, and SBS-modified emulsified asphalt) were designed and tested. Through shear test, wheel-load fatigue test, and pressurized seepage test, the variation trends of interlayer shear, crack resistance, and waterproofing under different combination schemes were obtained. Finally, the matching relationship between different working conditions and interlayer treatment measures was established. The results show that the actual working conditions of an airport asphalt pavement can be divided into three levels. Combined with the performance ranking of different materials and interlayer treatment measures, the recommended interlayer treatment measures for comprehensive classifications I, II, and III are two oils and one material + SBS-modified asphalt, asphalt precoating, or geogrid + SBS-modified emulsified asphalt or ordinary hot asphalt, and geotextile + ordinary hot asphalt, respectively. The working conditions in Juba Airport in South Sudan can be classified as comprehensive classification II, the recommended treatment measures for geogrid + ordinary hot asphalt., 1. Introduction Airport pavements in hot and humid areas suffer from structural and functional deficiencies because of bad weather conditions, large number of aircrafts, and surge in air traffic [1, [...]

The arch expansion of cement stabilised base materials has become increasingly serious due to the current design guideline, typical climate and geological environment in the west of China. This research systematically investigated the influence of different factors on temperature expansion and also salt expansion of the cement stabilised base course through laboratory-scale slab tests and microscopic tests. Optimised gradation type of aggregate and other design indexes were proposed. The radial basis function network (RBFN) was used to establish a predication model of the amount of arch expansion. The micro-mechanism of arch expansion was further detailed by scanning images. The test results showed that the temperature expansion occurred most significantly during 20°C to 40°C and the optimised gradation could alleviate the arch expansion effectively. In the range of 20°C to 30°C, the arch expansion of cement stabilised materials was dominated by temperature expansion, and the expansion was mainly salt expansion between −10°C and 0°C. It is suggested that reasonable prevention measures should be taken considering different environmental factors by the inhibition weight 1/di, and thus the most effective preventing methods of arch expansion would be taken. [ABSTRACT FROM AUTHOR]