Investigation of the Road Performance of AH-30 Bitumen and Its Mixture: Comparison with AH-70 and SBS-Modified Bitumen

AH-30 is a type of high-viscosity matrix asphalt. The asphalt mixture made by AH-30 as a binder has an excellent antirutting performance. However, the other road performance of AH-30 was still worthy of attention. This research aims to reveal the properties of AH-30 and its impact on the road performance of asphalt mixtures (AH30-AC20/25). The AH-70 neat asphalt and SBS modified asphalt were prepared for comparison. The high-temperature sensitivity and fatigue resistance of AH-30 are evaluated by the dynamic shear rheological (DSR) test. The low-temperature performance is evaluated by the bending beam rheometer (BBR) test. The high-temperature stability (HTS) of AH30-AC20/25 is carried out by the wheel tracking (WT) test and the repeated shear constant height (RSCH) test. The low-temperature crack resistance (LTCR) is carried out by the direct stretching (DS) test. The fatigue property is carried out by the three-point bending test. Water stability (WS) is carried out by the Marshall residual stability (MRS) and the intensity ratio of the frozen and melted (IRFM) test. The test results show that the high-temperature resistance of AH-30 is better than that of AH-70. The low-temperature crack resistance of AH-30 is equivalent to that of AH-70. The AH-30 as a binder can meet the requirements of the roads, which are located at a minimum temperature of not less than −10.5°C in winter. The fatigue property of the AH-30 asphalt mixture is poor, which may be one reason why AH-30 asphalt pavement is more prone to cracking. The water stability of the AH30-AC (20/25) asphalt mixture can meet the specification requirements, and AH30-AC20 is better than the other two asphalt mixtures. The research of this paper will provide a basis and reference for the popularization and application of AH-30 in asphalt pavement.

Effect of aging on low-temperature crack resistance and water stability of polyester fiber asphalt mixture

In order to study the influence of different aging conditions on the low-temperature crack resistance and water stability of polyester fiber asphalt mixture. Prepare standard Marshall specimens of asphalt mixture with 0.4 % polyester fiber doping, and carry out water immersion Marshall test and low temperature splitting test through indoor asphalt mortar aging, asphalt mixture short-term aging and long-term aging. The results show that: under the three aging conditions, when the water immersion and low temperature time are fixed, with the increase of the aging degree, the water stability and low temperature crack resistance of the asphalt mixture decrease. When the immersion time is 2 h, the stability of asphalt mortar aging and short-term aging decreases by 6.0% and 11.8%, respectively, compared with unaging, but the long-term aging is only 3.6% lower than the short-term aging. When the temperature is -5℃, the split tensile strength of asphalt mortar aged and short-term aged increases by 4.24% and 14.35%, respectively, compared with unaging, while long-term aging only increases 4.18% compared with short-term aging. This indicates that the short-term aging condition has the most significant effect on the water stability and low-temperature crack resistance of polyester fiber asphalt mixes. At the same time, this study established a regression equation between the test temperature and the low temperature evaluation index through quadratic fitting (the correlation coefficient is 0.960-0.998), and the regression relationship can be used to estimate the low temperature evaluation index at different test temperatures.

Study on the Optimum Steel Slag Content of SMA-13 Asphalt Mixes Based on Road Performance

To reduce the use of aggregates such as limestone and basalt, this paper used steel slag to replace some of the limestone aggregates in the production of SMA-13 asphalt mixes. The optimum content of steel slag in the SMA-13 asphalt mixes was investigated, and the performance of these mixes was evaluated. Five SMA-13 asphalt mixes with varying steel slag content (0%, 25%, 50%, 75%, and 100%) were designed and prepared experimentally. The high-temperature stability, low-temperature crack resistance, water stability, dynamic modulus, shear resistance, and volumetric stability of the mixes were investigated using the wheel tracking, Hamburg wheel tracking, three-point bending, freeze–thaw splitting, dynamic modulus, uniaxial penetration, and asphalt mix expansion tests. The results showed that compared to normal SMA-13 asphalt mixes, the high-temperature stability, water stability, and shear resistance of the SMA-13 asphalt mixes increased and then decreased as the steel slag content increased. All three performance indicators peaked at 75% steel slag content, and the dynamic stability, freeze–thaw splitting ratio, and uniaxial penetration strength increased by 90.48%, 7.39%, and 88.08%, respectively; however, the maximum bending tensile strain, which represents the low-temperature crack resistance of the asphalt mix, decreased by 5.98%. The dynamic modulus of the SMA-13 asphalt mixes increased with increasing steel slag content, but the volume expansion at a 75% steel slag content was 0.446% higher than at a 0% steel slag content. Based on the experimental results, the optimum content of steel slag for SMA-13 asphalt mixes was determined to be 75%.

Performance Characteristics of Epoxy Modified Open Graded Friction Course (OGFC) By Post-doping Methods

To improve drainage properties and increase driver’s safety in wet weather, epoxy modified Open Graded Friction Course (OGFC) by post-doping methods was proposed. The predominant focus of this paper evaluated the performances of epoxy modified Open Graded Friction Course (OGFC) such as rutting resistance at high-temperature, crack resistance at low temperature, friction, moisture resistance and coefficient of permeability. For comparison, the same NMAS Open friction course with epoxy asphalt which was supplied courtesy of ChemCo Systems Ltd and SK High-Viscosity Asphalt were cited. In addition, the harsh construction requirements and application limitations caused by the residence time of epoxy asphalt were solved by the post-mixing process which was produced by two steps, First step, component B of epoxy asphalt was produced in the backyard plant, then suitable amount of component A was added and mixed evenly while paving in site, affecting the holding time only in the two links of paving and rolling, and the time was easy to control. The results show that epoxy modified Open graded friction Course reinforced with Basalt fiber produced by post-mixing methods has good friction resistance and permeability while retaining satisfactory performance and mechanical properties.

Room temperature crack-healing in an atomically layered ternary carbide

Ceramic materials provide outstanding chemical and structural stability at high temperatures and in hostile environments but are susceptible to catastrophic fracture that severely limits their applicability. Traditional approaches to partially overcome this limitation rely on activating toughening mechanisms during crack growth to postpone fracture. Here, we demonstrate a more potent toughening mechanism that involves an intriguing possibility of healing the cracks as they form, even at room temperature, in an atomically layered ternary carbide. Crystals of this class of ceramic materials readily fracture along weakly bonded crystallographic planes. However, the onset of an abstruse mode of deformation, referred to as kinking in these materials, induces large crystallographic rotations and plastic deformation that physically heal the cracks. This implies that the toughness of numerous other layered ceramic materials, whose broader applications have been limited by their susceptibility to catastrophic fracture, can also be enhanced by microstructural engineering to promote kinking and crack-healing.

Road Performance and Application Analysis of Ultra-Thin Asphalt Coating Mixture with High Elastic Modification

A kind of composite modified asphalt with high elasticity was prepared by SBS and high elasticity agent, and the asphalt mixture with easy compactness was applied. The high temperature, low temperature, water stability and fatigue properties of the mixture were evaluated by laboratory tests. The results show that the optimum content of high elasticity agent is about 6% for SBS modified asphalt. The pavement performance of the high-elasticity modified asphalt compacting mixture was improved to a certain extent. Compared with SBS modified asphalt SMA-13, the dynamic stability was increased by 13.5%. The water stability, low temperature crack resistance and fatigue resistance increased by 10.4%, 59.3% and 173%.