Key Engineering Materials Vol. 599

Abstract: In this research, the potential of using steel slag asphalt mixture as a self-healing material was investigated by means of microwave heating. The microwave heating rate and thermal conductivity of asphalt mixtures were tested respectively. The result shown that, the heating rate of steel slag asphalt mixtures is approximately two times faster than limestone asphalt mixtures. While its thermal conductivity is slightly lower. It is concluded that microwave heating can be used to promote self-healing of steel slag asphalt mixture.

Abstract: Abstract. Aging of asphalt is a serious problem of asphalt damage and occurs throughout its service life. In general, a common method is to use different additives or modifiers for anti-aging. The objective of this study was to investigate the effects of layered double hydroxides(LDHs) additives on anti-aging mechanism using molecular simulations. Molecular dynamic simulations were used to simulate the changes of physical properties and structure before and after aging. Results showed that the degradation of asphalt was dominant reaction and modified asphalts had a high-temperature stability at thermal aging without oxygen. Owing to the difference of polarity between LDHs and asphalt components, phase separation phenomenon would occur at thermal oxidative aging. LDHs also increased the orderliness of asphalt binder.

Abstract: Layered double hydroxides (LDHs)/SBS modified bitumens used for waterproofing membrane were prepared by melt blending using various contents of SBS and LDHs. Effects of the LDHs on physical properties and thermal oxidative aging performance of modified bitumen were investigated. The results show that softening point and low temperature flexibility of LDHs/SBS modified bitumen are increased simultaneously with the rise of SBS content, while they are little affected by the change of LDHs content. The thermal oxidative aging resistance of SBS modified bitumen is gradually improved with increasing LDHs content. In addition, the aging rate of SBS modified bitumen with LDHs are evidently lower than that without LDHs over time, which indicates that LDHs improve the ability of SBS modified bitumen to resist the thermal oxidative aging effectively.

Abstract: Steel slag reserves of our country has reached 200 million tons and each year it will increase 100 million tons. Slag accumulation occupied a large number of enterprises space and made pollution to the environment. Since steel slag based asphalt pavements have been utilized for a certain history, their fatigue life necessitates comprehensive investigation imperatively. In this paper, the fatigue life of steel-slag asphalt mixture was tested through the four-point bending test. The results showed that steel slag prepared mixture was superior to limestone mixture after several freeze-thaws, with respect to moisture sensitivity, and was suitable for asphalt treated base (ATB). The fatigue life of slag asphalt mixture with low content limestone was longer.

Abstract: Aiming at the fatigue cracking problem of the asphalt mixture on steel deck pavement surface, high-elasticity modified asphalt was developed. high-temperature properties, low-temperature properties and fatigue properties of modified asphalt and modified asphalt mixture were tested. The fatigue life of high-elasticity modified asphalt has been greatly improved, which was at least 25 times as long as that of common asphalt. The mechanism was explained clearly that the fatigue life of asphalt mixture could be improved by reducing the failure energy after each hysteresis loop of asphalt mixture, according to the dissipated energy theory for asphalt mixture. Projects proved that high-elasticity modified asphalt extremely improved the fatigue life of asphalt mixture on the steel bridge deck.

Abstract: In this paper the effect of Active mineral powder (AMP) on the fundamental behavior of asphalt concrete especially in moisture damage was studied. Polycyclic Soaking Marshall test and freeze-thaw and splitting test were used to investigate the resistance of mixtures to moisture damage. Dynamic stability of mixture was evaluated by soaking rutting and the fatigue life of asphalts mixture with and without AMP was measured by universal test machine (UTM). After adding AMP, Retained Marshall Stability, Tensile Strength Ratio and dynamic stability value of asphalt concrete is higher than that of non-containing AMP asphalt concrete. The failure life of asphalt concrete increased as adding AMP. The results showed that the addition of AMP could improve the performance of failure life and resistance to moisture damage.

Abstract: Based on influence of bridge structure caused by vibrating compaction and the properties of road roller, the combination of vibrating compaction and rubber-tyred kneading rolling can ensure the construction quality of cement concrete bridge deck asphalt mixture surfacing. It can guarantee the smoothness of asphalt mixture surfacing and avoid the shortage of compaction.

Abstract: An unanticipated sideeffect of China’s developing economy was the increase in heavy road trafficvehicles utilizing high pressure tires on both new and old infrastructure.Today the extent of rutting has become one of the main forms of asphalt road surfacebreakage. To improve the robustness and high temperature properties of roadsurfacing asphalt, a new high-modulus material has been developed and used tomodify normal road petroleum asphalt. The results from laboratory experimentsconducted at the Jiangsu Baoli Asphalt Co., LTD and real road trials inPeople's Democratic Republic of Algeria, Shanghai, Shanxi and Jiangsu provincein China, indicate that the high-modulus asphalt performed significantly betterat higher-temperatures when compared to samples of more commonly used asphaltmixtures. The high-modulus additive (No. ZQ-1) was prepared in Jiangsu BaoliAsphalt Co. LTD, and the basic production process, the basic properties as wellas the effection to base bitumen was analysed in the paper. And the DynamicStability was evaluated using an automated rut-depth measuring system. Thewater stability and low temperature properties were also discussed. Themodified asphalt material has comparable storage and usage costs to existingutilized asphalts though with enhanced high-temperature properties.

Abstract: Grey relational analysis (GRA) is an important data handling techniques. In this paper, combining the characteristics of asphalt mixture, the method of GRA is applied to the study of coarse grading. The high temperature stability, low temperature cracking resistance and water stability of asphalt mixture with different grading were evaluated in the laboratory. The results showed that OGFC-25 gradation apply to asphalt mixture that demand high temperature stability. Similarly, ATB-25 gradation benefit low temperature performance and SUP-25 benefit water stability.

Abstract: Modification of asphalt binders has increasingly become the norm in designing optimally performing pavement. In this paper, an anti-rut agent was used as a modifier to add into base asphalt and its effects on the property of the asphalt were investigated. A shear blender was used to ensure a good distribution of the anti-rut agent. The conventional physical properties test and Dynamic Shear Rheometer (DSR) test were used to evaluate the properties of the asphalt. The results showed that the softening point and rutting parameter increases significantly, the ductility and penetration decrease due to the introduction of the anti-rut agent. Besides, the result of fatigue test showed that excess anti-rut agent may lead a deterioration in the fatigue life. Key word: Anti-rut agent; Rutting parameter; Rheological property; Fatigue life.