Study On Performance And Mechanism Of Crumbrubber Recycled Asphalt

At present,the development of China’s transportation industry has entered a stable period,and the national highway network tends to be perfect.Therefore,road repair and maintenance are extraordinarily necessary.In the process of asphalt road maintenance,19 million tons of waste mixture is remoced every year in China.It is urgent to solve the problem of recycling waste asphalt and stone.Asphalt mixture recycling technology emerges as the time requires.This paper proposed a new secondary modified regeneration method of adding asphalt regenerant and rubber powder at the same time to recycle asphalt.This method was applied to treat the aged asphalt and the aged SB S modified asphalt respectively,and the regeneration effect of crumb rubber recycled asphalt was evaluated by comprehensive macro and micro indexes.Based on the four aging mechanisms of base asphalt and SBS modified asphalt,this paper expounded the similarities and differences of the two asphalt regeneration mechanisms.Based on the composite modification mechanism and the secondary modification theory of aging asphalt,the feasibility of adding rubber powder and tall oil at the same time was discussed.In the preliminary test,two kinds of asphalt with moderate aging level were prepared by extending the aging time of film oven,and then nine groups of rubber powder and tall oil with different proportions were added to the aging asphalt to prepare rubber powder recycled asphalt.According to the requirements of Technical Specification for Construction of Highway Asphalt Pavement(JTG F40),the rubber powder tall oil recycled asphalt meeting the standard was selected.The conventional indexes and dynamic shear rheological indexes of the matrix and SBS modified asphalt before aging,after aging and after regeneration were tested.The results showed that the performance of the aged asphalt and SBS modified asphalt could be restored to the standard level by adding the regenerant alone or adding the regenerant and rubber powder at the same time,but the one adding the regenerant alone was more suitable for the asphalt and the way of mixing the rubber powder and regenerant at the same time was more suitable for SBS modified asphalt.The micro modification mechanism of crumb rubber in aged SBS modified asphalt was analyzed by fluorescence microscope and Fourier transform infrared spectrometer.It was found that crumb rubber could cross link with the residual SBS molecules in aged SBS modified asphalt to form a new structure.As a result,the secondary modification effect of crumb rubber in aged SBS modified asphalt was better than that of asphalt.