| Modified Asphalts and warm-mixed agents have been successfully used in the construction of high-grade highway. There is no effective solution to solve the contradiction between excellent performance of pavement and the lower cost. So it is meaningful to build a new strategy to relieve the tension.It is “the ready mixed-enhanced” mixing processes that are proposed based on the research about the micro modification mechanism of natural asphalt. Firstly, soft asphalt and mineral aggregate were mixed in order to reduce the gas emissions and ensure workability of the mixture construction at the same time. Then, natural hard asphalts were used to mix the aggregate again with the purpose of low carbon environmental protection and performance improvement. Besides, the mixture composition design method, road performance, preparation process and economic and environmental benefits were studied. The research content as follows.Firstly,the application of natural asphalt in the road engineering in China and abroad was investigated and then the physical and chemical composition of natural asphalt was analyzed. The natural asphalt performance improvement mechanism of the composite cement was studied through fluorescence microscope, infrared spectrum analysis and other micro technology. The result showed that natural bitumen contains O, N, P and other atoms which help composite cement improve the performance of anti-oxidant and anti-stripping. It proved that “the ready mixed-enhanced” mixing processes were feasible.Secondly, the research on natural compatibility of natural asphalt indicated that with the increase of dose of natural asphalt, the high temperature property and aging performance of binder improved.The greater the dose, the more obvious the effect. But this was bad for the low temperature performance. At last, the optimum content of natural asphalt was recommended as the "enhanced" function considering the various performance indicators.Thirdly, pavement performance and construction technology of ready mixed-enhanced friendly asphalt mixture were studied, and the results showed that ready mixed-enhanced friendly asphalt mixture can achieve the same road performance as the SBS modified asphalt mixture under the condition of reducing mixing temperature about 30℃. In the preparation process, the mixing time and temperature should be controlled accurately to guarantee the construction quality. This ensured pavement to achieve the best performance.Finally, compared with the warm and hot asphalt mixtures,the friendly asphalt mixtures achieved the best economic and environmental benefits. Moreover, the energy consumption in the process of production and the emission of harmful gases were calculated. The results showed that ready mixed-enhanced friendly asphalt mixture had the least gas emissions. Thus it would have good potential application.Ready mixed-enhanced friendly asphalt mixture improved pavement performance with the remarkable economic and environmental benefits. It is in line with the purpose of sustainable development and has a widely prospect to apply. |
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