Research On Performances For BRA Modified Asphalt And Its Mixture

As the modern highway transportation characterized with high speed, high traffic density, heavy load and channelized traffic, many methods had been applied to improve the performance of asphalt pavement, such as the Superpave, the technology of modified asphalt, the SMA, etc. Otherwise, the natural modified asphalt pavement is a successful alternative. It is expectative for its eminent performance, simple construction technology and economical preponderance. Therefore, based on the researches of relevant references and experiences at home and abroad, plenty of experiments are carried out in combination with theory analysis, and the paper develops the researches on performances for BRA modified asphalt and its mixture (BRA: Indonesian Buton Rock Asphalt).1. It studies on the characteristics of BRA through the tests, including its characters, composition and modified mechanism. Its physical indexes all accord with the standards of Indonesian. Then, it carries on the traditional experiments of different contents of BRA modified asphalt; the results show that BRA can improve and enhance several performances of the basis asphalt greatly, such as the temperature susceptibility, high-temperature performance, low-temperature performance and resistance to ageing. With the increasing of BRA's content, the improvement is more effective. However, the more limestone mineral which is contained in BRA can influence the results of experiment, for example ductility and mass loss, thus it need to test the further pavement performances of BRA modified asphalt mixture to evaluate. Therefore, synthetically considering the modification effects of BRA for basis asphalt, the optimal content extension of BRA is determined as 10%~30%.2. It carries on the SHRP experiments of different contents of BRA modified asphalt, including DSR, BBR and BV. The results show that the high-temperature performance, the temperature susceptibility and the performance of rutting-resistance of BRA modified asphalt are improved obviously with the increasing of BRA's content. But in order to avoid the influence which is caused by the ash mineral in BRA to the low- temperature performance, the advisable content of BRA is not more than 30%.3. According to the successful experiment of the actual engineering of surface layer of asphalt pavement in DS19 bid section of eastern line in the First Loop Expressway of Fast Main Highway of Foshan City, the paper adopts its match ratio AC-13C. Then, the paper determines the optimal oilstone ratio and tests the pavement performances of BRA modified asphalt mixture and ordinary asphalt mixture. The results of comparative analysis shows: at the same situation, no matter in the mineral or in the gradation, the BRA modified asphalt mixture's high-temperature stability, low-temperature stability, the water stability as well as skid resistance with the impermeability can all be improved obviously. Synthetically considering the indexes of BRA modified asphalt and its mixture and the economical factors in the engineering application, the optimal content of BRA is 20%.4. The performance evaluation indexes, the technical requirements and the construction techniques of BRA modified asphalt and its mixture are put forward in accordance with the indoor test results and practical experience. The economical analysis shows that the BRA modified asphalt concrete pavement has favorable economic and social benefits and application prospects.Therefore, the research results such as optimal content, performance evaluation indexes and construction techniques for BRA modified asphalt and its mixture provide the reasonable reference for the applications and promotion among the engineering of BRA modified asphalt and its mixture.