Research On Performances Of Ash Influencing On TLA Modified Asphalt And Its Asphalt Mixture

Trinidad Lake Asphalt (TLA) contains about 35% to 37% of the mineral fine particles (ash). Because ash density is more than pure asphalt density, TLA modified asphalt products are easy to produce ash segregation in the process of storage and transportation. Then its service performances will caused deterioration. For this point, the paper combined with 40% TLA modified asphalt pavement construction of Foshan Expressway of the First Loop around the city, then centering on ash is to the systematic theoretical analysis and indoor test of TLA modified asphalt and its mixture, then the control indexes of ash and construction proposal are suggested.1) The methods of TLA modified asphalt preparation and ash content determination in laboratory were determined, and designed the instrument (sedimentation cylinder) of how to test the settlement regulation of TLA modified asphalt ash. The TLA modified asphalt is divided into 7 layers by the order from top to bottom (high and radius are all 4 cm), and five kinds of settlement time were selected respectively to determine the ash content of different settlement time and layers. The results show that the 1st layer and the 7th layer are the largest and the smallest limit layer of ash content respectively during the all process of settlement, and the ash content in the middle layers is changed in the range of ash content among the limit layers. As the time of settlement time was growing, ash sedimentation segregation will be more and more obvious. This shows that the reducing trend of ash content in the top layer of asphalt tank is most obvious in the process of storage and transportation for TLA modified asphalt, on the contrary, the increasing trend of ash content in the bottom layer is most apparent.2) The preparation methods of TLA modified asphalt with different ash content were determined, thus the performances of TLA modified asphalt with different ash content were tested. The results showed that: TLA modified asphalt in the range of ash content from 10.80% to 19.76%, the softening point 53.6℃does not satisfy the technical requirements only when the ash content is 10.80%. With the growth of ash content, the indexes of TLA modified asphalt such as temperature susceptibility, high temperature properties and anti-deformation capacity have been enhanced. However, the indexes of low temperature performance were reduced, and the changes of anti-aging performance indexes were inconsistent. This is mainly due to ash content which makes TLA modified asphalt into asphalt mortar, so the further inspection should be take to test the influences of ash on the mixture performances. Therefore, the performances of low temperature and aging should be primarily evaluated with thetests of its asphalt mixture performances.3) The modified formulas of mixture ratio were suggested for TLA modified asphalt mixture with the extract test, accordingly, the reasons of the impact on mixture performances were analyzed because of ash segregation. In 10.00% to 20.00% of the ash content, the performances of 6 to 8 groups of different ash content of TLA modified asphalt surface layer AC-13C (TAC-13C) were tested respectively. We can obtained the conclusions: only when the ash content is 18.89%, porosity, flow value and residual stability were 5.3%, 4.11mm and 84.71% respectively, and it does not satisfy the technical requirements of specifications; the performance indexes of the others can meet specifications requirements. At the same time, Marshall indexes, high temperature stability, water stability and impermeability as the ash content increasing appeared the trend of firstly best to lastly worse as a whole, but anti-sliding performance had nothing to do with ash content.4) According to the test results of ash settlement regulation of TLA modified asphalt and the effect of ash on the performances of TLA modified asphalt and its mixture, the control range of ash content was suggested as 11.5% to 18.0% for 40% TLA modified asphalt, and the longest allowable settlement time should be limited in 120min. According to the control indexes of ash for 40% TLA modified asphalt, the ash control indexes of arbitrary mixture ratio of TLA modified asphalt were put forward. Finally, combine with the ash control indexes and the practical experiences, the construction suggestions of TLA modified asphalt pavement with considering the effect of ash were summarized from five aspects of control indexes, production, transportation, application and mixture ratio of TLA modified asphalt respectively.In brief, the ash control indexes and the construction suggestions with considering the effect of ash for TLA modified asphalt in this paper will provide scientific and reasonable reference for construction quality control of TLA modified asphalt pavement in our country.