Research On Application Technology For TLA Modified Asphalt Mixture

Now in highway asphalt pavements there are many common distresses such as ruts, cracks and water damage. In order to ensure the performance requirements of high strength, stablility, safety, durablility for asphalt pavements, the applications of modified asphalt become the main method. Therefor, based on the researches of relevant references and experiences at home and abroad and combined with the asphalt pavement construction of Foshan Expressway of the First Loop around the city, the paper develops the researches on the performances and the application techniques of TLA modified asphalt mixture.Firstly, it carries on the experiments of different contents of TLA modified asphalt; the results show that the temperature susceptibility and high-temperature capability of TLA modified asphalt are improved obviously with increase of the TAL's contents. But, improvement to the low temperature capability and durability are ineffective; it is mainly caused by the ash that contained in TLA. It needs evaluate with the further pavement performances. Therefore, the economical content of TLA is synthetically determined as 40%, which the modification effects are well and meets needs of every performance indexes.Secondly, 5 factors such as the passing rate of 4 sieve sizes of 9.5mm, 4.75mm, 2.36mm and 0.075mm and asphalt-aggreagte-ratio and 5 relevant levels are selected according to the recommended gradation range from"Technical Specification for Construction of Highway Asphalt Pavements"(JTG F40-2004) and the field grades of aggregate. Thereout, the orthogonal array L₂₅(5⁶) is chosed to arrange and carry through Marshall experiments. With the methods of range analysis and variance analysis, the paper analyzed the effect degrees and laws of Marshall indexes caused by all kinds of factors and levels, the results indicate that 2.36mm passing rate is the most important influence factor to stability and Voids in Mineral Aggregate, and the asphalt-aggregate-ratio is the most important influence factor to Volume of Air Voids, flow value and Voids Filled with Asphalt. At the same time, it analyses the optimal compounding of each factor and level which is satisfied the Marshall experiment indexes, thereby, it determines AC-13C gradation range of TLA modified asphalt mixture which is satisfied requirement of all kinds of technique indexes.Thirdly, the mix design of TLA modified asphalt and ordinary asphalt mixture are carried on according to the results of AC-13C gradation optimum, at the same time, the mix design of middle surface layer TLA modified asphalt and ordinary asphalt mixture are put up according to the recommended gradation range of AC-20C in the specifications. Thereout, the paper tests the pavement performances of AC-13C and AC-20C with the optimal ratio of mixture, and contrasts the performances of TLA modified asphalt mixture and ordinary asphalt mixture. The experiments indicate that, by adding TLA natural asphalt, at the same situation, no mater in the mineral or in the gradation, the 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.Then, the TLA modified asphalt mixture construction techniques, the key techniques and the quality control measures and standards are put forword in accordance with the indoor test results. The influences of the ash content of TLA to gradation and asphalt-aggregate-ratio are mainly analyzed for the mixture extract test. Hereby, the trial roads of the middle surface layer AC-20C on K4+600^K4+900 and the top layer AC-13C on K24+300^K24+600 are constructed in Foshan Expressway of the First Loop around the city, and the quality control to field construction is carried through. The compaction effect, strength and stiffness of the pavements are examined and analysed. The results show that the construction process is controlled well in gradation and asphalt-aggregate-ratio in the blender, the construction organization and the compaction effect. The pavement performances of trial roads have been satisfied since they were open to traffic half a year ago.Therefore, the researches such as ratio of mixture, performance evaluation indexes, construction techniques, key technologies and construction quality control standards for the TLA modified asphalt and its mixture provide the reasonable reference for the further applications of TLA modified asphalt and its mixture.