Search

• A simplified skeleton method for coarse aggregates analysis of asphalt mixtures was proposed. • The stress transfer paths and load transfer efficiencies of three typical gradations were studied. • Eff skeleton reflected the load transfer efficiency of the coarse aggregate skeleton under no-load conditions. • The DisP value reflected the load transfer efficiency of the coarse aggregate skeleton under a specific load. Studies on asphalt mixture skeletons have primarily focused on the statistical skeleton morphology while neglecting internal stress transfer. This study therefore proposed a simplified reconstruction-based coarse aggregate skeleton method for analyzing asphalt mixes using the force chain concept from granular matter mechanics. The stress transfer paths and load transfer efficiencies were investigated for three typical aggregate gradations (AC-13, SMA-13, and OGFC-13) and an analysis of their correlation with uniaxial penetration test results was performed. The AC-13 mixture exhibited the largest uniaxial penetration strength (3.30 kN on average) at the lowest failure displacement (4.1 mm on average). As the characteristics of the simplified skeleton were shown to be related to the number of contact points provided between large aggregate particles, the force chain morphology was closely linked to the mixture gradation. The ratio of strong to weak force chains in the AC-13 mixture was approximately 0.77, whereas those of the SMA-13 and OGFC-13 mixtures were significantly different at 0.90 and 1.13, respectively. The transfer efficiencies of the AC-13, SMA-13, and OGFC-13 specimen skeletons considering morphology alone (i.e., under the no-load condition) were 20.94 %, 62.34 %, and 73.57 %, respectively. However, the correlation between the load transfer efficiency of the coarse aggregate skeleton under a specific load and the observed penetration strength reached 0.9. Thus, the simplified skeleton analysis method proposed herein was shown to satisfactorily retain the skeletal characteristics of the mixes. [ABSTRACT FROM AUTHOR]

• The variation laws of mortar indicators were investigated by performance tests. • The correlation between mortar performance and mixture performance was analyzed. • Mixture with excellent anti-rutting and deformation performance was designed. • The design method can realize the coordination of rutting and crack resistance. The anti-rutting and anti-cracking performance of asphalt mixtures are a pair of contradictions that are difficult to coordinate. In order to ensure the rutting resistance of asphalt mixture to meet the requirements of the specification, while improving its deformation capacity and crack resistance. Based on the mortar performance, the Anti-rutting and High Ductility Asphalt Mixture with excellent anti-rutting performance and deformation performance was designed in this paper. With the filler-asphalt ratio as the control index, SBS modified asphalt and SHV modified asphalt was selected to design five asphalt mortars with different filler-asphalt ratios of 0, 0.5, 1.0, 1.5, 2.0. Variation laws of mortar technical indicators were investigated by rotational viscosity test, cone penetration test, and BBR test. Asphalt mixtures were prepared and a rutting test and small beam bending test were carried out to ensure the consistency of the mixture skeleton state by grouting molding. The influence of the mortar performance index on the road performance of the mixture was evaluated by conducting correlation analysis, and then an anti-rutting and high-ductility asphalt mixture was proposed based on mortar performance. The obtained results showed that the technical indicators of asphalt mortar had a good correlation with the filler-asphalt ratio, and the developed regression model could be used to determine the correlation and design of the mortars. The technical performance index of mortar was found to be directly correlated with the road performance index of the mixture. The developed anti-rutting and high-ductility asphalt mixture not only had good anti-rutting performance but also had good deformation capacity and cracking resistance. Its anti-rutting performance could meet the specification requirements, and the maximum flexural strain could reach 7161 με. The performance of asphalt mortar determines the road performance of the mixture. The rutting resistance and cracking resistance of the mixture could be coordinated by designing asphalt mortar to improve its comprehensive road performance. To guarantee that the dynamic stability of the mixture met the required specifications and the deformation ability was good, the critical value of each technical index of asphalt mortar was recommended. [ABSTRACT FROM AUTHOR]

• An asphalt mixture shear modulus model is proposed based on granular mechanics theory. • The model was verified with an asphalt mixture analysis system and a pressure film. • Contact area, stress distribution, and total stress were measured accurately. • Our model quantified the binder and gradation effects on the asphalt's shear modulus. This study proposes a mechanical model for the shear modulus of asphalt mixtures based on granular mechanics theory. An aggregate interface shear test is conducted to validate the proposed model with the asphalt mixture particle shear analysis system and a pressure film. Results show that the pressure film can measure accurately the contact area, stress distribution, and total stress of the contact interface. It is demonstrated that more than 65% of the contact area bears only 37.5% of the total load, and the contact interface exhibits an uneven stress distribution. The binder type has a significant influence on the shear force at the contact interface. As the penetration of the asphalt decreases, the softening-point temperature increases; as the rutting factor increases, the tangential elastic stiffness also increases. The proposed mechanical model can distinguish the influences of the binder and gradation on the shear modulus of asphalt mixtures. [ABSTRACT FROM AUTHOR]

• Exploring the thermal performance of phase change asphalt mixture. • Equal volume replacement of mineral filler and fine aggregate with CPCMs. • Exploring the mechanical strength of phase change asphalt mixture. Phase change materials (PCMs) have the capabilities of thermal energy storage and temperature regulation. However, the application of PCMs in asphalt pavements is still limited due to the severe leakage and low thermal performance problem. In this research work, the phase change asphalt mixture (PCAM) with Polyethylene glycol/hydrophobic fumed silica composite phase change material (PEG/HFS) and Polyethylene glycol/SiO 2 composite phase change material (PEG/SiO 2) replacing mineral filler and fine aggregate was prepared and tested. The leakage experiment illustrated that the PEG/HFS with PEG content of 45% (wt) and PEG/SiO 2 with PEG content of 70% (wt) had good thermal exudation stability. The results of XRD and FTIR showed that the preparation process of composite phase change materials (CPCMs) was a pure physical mixing process without chemical reactions. In addition, based on the results of the indoor radiation test, Marshall test, and rutting test, we found that when mineral filler and fine aggregate were replaced by 25% of the same volume of CPCMs, the PCAM exhibited a better cooling effect and relatively small decrease in mechanical strength. Therefore, the PCAM developed in this research has great potential for improving the thermal performance of asphalt steel bridge deck. [ABSTRACT FROM AUTHOR]