ORCID Profile
0000-0002-9814-6387
Current Organisation
University of Adelaide
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Publisher: MDPI AG
Date: 18-09-2022
DOI: 10.3390/MA15186472
Abstract: Epoxy asphalt concrete (EAC) has excellent properties such as high strength, outstanding thermal stability, and great fatigue resistance, and is considered to be a long-life pavement material. Meanwhile, the low initial viscosity of the epoxy components provides the possibility to reduce the mixing temperature of SBS-modified asphalt. The purpose of this study is to verify the feasibility of low-emission mixing of SBS-modified epoxy asphalt and to compare the mechanical responses in several typical structures with EAC, in order to perform structure optimization for practical applications of EAC. In this paper, the Brookfield rotational viscosity test was conducted to investigate the feasibility of mixing SBS-modified epoxy asphalt at a reduced temperature. Subsequently, the dynamic modulus tests were carried out on EAC to obtain the Prony series in order to provide viscoelastic parameters for the finite element model. Six feasible pavement structures with EAC were proposed, and a finite element method (FEM) model was developed to analyze and compare the mechanical responses with the conventional pavement structure. Additionally, the design life was predicted and compared to comprehensively evaluate the performance of EAC structures. Finally, life cycle assessment (LCA) on carbon emissions was developed to explore the emission reduction effect of the epoxy asphalt pavement. The results indicate that the addition of epoxy components could reduce the mixing temperature of SBS-modified asphalt by 30 °C. The proper use of EAC can significantly improve the mechanical condition of the pavement and improve its performance and service life. It is recommended to choose S5 (with EAC applied in the middle-lower layer) as the optimal pavement structure, whose allowable load repetitions to limit fatigue cracking were more than 1.7 times that of conventional pavements and it has favorable rutting resistance as well. The LCA results show that in a 25-year life cycle, the carbon emissions of epoxy asphalt pavements could be reduced by 29.8% in comparison to conventional pavements.
Publisher: Elsevier BV
Date: 04-2020
Publisher: Elsevier BV
Date: 2022
Publisher: MDPI AG
Date: 29-08-2021
DOI: 10.3390/APP11177990
Abstract: Cracks are one of the main problems that plague road workers. A correct understanding of the internal crack propagation mechanism of asphalt pavement will help road workers evaluate the road’s working status more comprehensively and make more reasonable decisions in design, construction, and maintenance work. This paper established a three-dimensional asphalt pavement layered model using the software ABAQUS and fracture mechanics theory and the extended finite element method were used to explore the mechanical response of the pavement base layer’s preset reflective cracks. This paper investigated the influence of the modulus of each layer, vehicle load on the principal stress, shear stress, J-integral, and two stress intensity factors (K1, K2) during the predetermined crack propagation process of the pavement base layer, and the entropy method was used to analyze the above-mentioned mechanical response. The results show that the main factor affecting the propagation of reflective cracks on asphalt pavements is the modulus of the bottom surface layer. However, from a modeling perspective, the effect of increasing load on crack growth is obvious. Therefore, in terms of technical feasibility, the prevention of reflective cracks should still be achieved by controlling the driving load and prohibiting overloading.
Publisher: American Chemical Society (ACS)
Date: 24-08-2016
Publisher: MDPI AG
Date: 11-04-2023
DOI: 10.3390/APP13084796
Abstract: Anti-skid performance is the most critical indicator that reflects the safety performance of the road surface. A good anti-skid performance of the road surface guarantees the safe and fast driving of vehicles. However, the asphalt pavement of highways has gradually exposed the anti-skid performance attenuation, which affects driving safety. Therefore, this study aims to accurately evaluate the anti-skid durability of asphalt mixtures based on a 1/3-size accelerated loading test with different anti-skid surfaces as the research object and explores the key factors affecting the long-term anti-skid performance of asphalt mixtures. The texture depth test and the pendulum value test show that the anti-skid durability of the SMA asphalt mixture is better than that of the AC asphalt mixture. The attenuation prediction equation of the British Pendulum Number (BPN), an anti-skid performance index based on an indoor accelerated loading test, was constructed. After the accelerated loading test stabilized, the BPN and BPN attenuation rate b were used as an index to evaluate the anti-skid durability of the asphalt mixture.
Publisher: American Chemical Society (ACS)
Date: 19-07-2017
Publisher: MDPI AG
Date: 29-08-2021
DOI: 10.3390/APP11177992
Abstract: Nanoindentation has been applied in the field of asphalt mixtures, but, at the nano-scale, changes in the composition of the mixture and material properties can have a significant impact on the results. Therefore, it is necessary to investigate the feasibility of nanoindentation tests on different types of asphalt mixtures with different gradations and the influence of material properties and test methods on nanoindentation results. In this paper, the nanoindentation test results on three kinds of asphalt mixture (AC-13, SMA-13, and OGFC-13) with different aggregate gradations were investigated. The load-displacement curves and moduli obtained from the nanoindentation tests were analyzed. In addition, nanoindentation tests were carried out before and after polishing with different ratios of filler and asphalt (RFA) (0.8–1.6). On this basis, the morphology of asphalt specimens with different RFAs is observed by scanning electron microscopy (SEM) imaging. The results indicate that using the nanoindentation test to characterize the mechanical behavior of asphalt mixture, the confidence level of the dense-graded mixture is low, and non-dense-graded mixtures are used as much as possible. Moreover, results illustrate that the nanoindentation modulus tends to increase as the RFA increases. and the SEM chart shows that the higher the mineral powder content in the mastic, the more complex the bitumen and mineral powder interaction surface, confirming the influence of mineral powder content on the nanoindentation test results. Furthermore, the effect of polishing is almost insignificant.
Publisher: Elsevier BV
Date: 09-2023
Publisher: MDPI AG
Date: 15-09-2023
Publisher: Wiley
Date: 02-07-2021
DOI: 10.1002/FAM.3004
Abstract: Eucalyptus is one of the most widespread genera around the world and a key element in recent wildfires. In a Eucalyptus forest, the accumulation of litter builds up a ground fuel layer that can support both flaming and smouldering wildfires. This work investigates the smouldering wildfire on leaf, bark, and twig beds (bulk density: 70‐140 kg/m 3 ) of Eucalyptus species. Two‐stage smouldering spread processes are observed. The first‐stage smouldering fire has the peak temperature of 600°C‐700°C and spread rate of 5‐9 mm/min. The measured emission factors are 1000‐1500 g/kg (CO2), 180‐450 g/kg (CO), 9‐16 g/kg (CH4), and 2‐6 g/kg (H2), respectively. The CO/CO2 ratio ranges from 0.15 (leaf) to 0.8 (bark). Laboratory experiments demonstrate that the smouldering fire spread is slower in leaf than those in bark and twig. The burning of stringy barks is less complete, compared to smooth barks. For leaf and twig beds, the influence of Eucalyptus species and heating value on smouldering fire is negligible. This is the first work to reveal smouldering fire behaviors on different Eucalyptus litter fuels and provides valuable information for understanding the effects of Eucalyptus species and plant parts on smouldering combustion.
Publisher: MDPI AG
Date: 03-10-2021
DOI: 10.3390/MA14195786
Abstract: In order to obtain more accurate parameters required for the simulation of asphalt mixtures in the discrete element method (DEM), this study carried out a series of cross-functional asphalt mixture experiments to obtain the DEM simulation meso-parameters. By comparing the results of simulation and actual experiments, a method to obtain the meso-parameters of the DEM simulation was proposed. In this method, the numerical aggregate profile was obtained by X-ray CT scanning and the 3D aggregate model was reconstructed in MIMICS. The linear contact parameters of the aggregate and the Burgers model parameters of the asphalt mastic were obtained by nanoindentation technology. The parameters of the parallel bonding model between the aggregate and mastic were determined by the macroscopic tensile adhesion test and shear bond test. The results showed that the meso-parameters obtained by the macroscopic experiment provide a basis for the calibration of DEM parameters to a certain extent. The trends in simulation results are similar to the macro test results. Therefore, the newly proposed method is feasible.
No related grants have been discovered for Houzhi Wang.