Abstract
An ultrathin wearing course is an effective maintenance treatment for prolonging the service life of asphalt pavements, which have been widely used in the field of pavement construction and road maintenance. However, the repeated vehicle load and wear results in a decreased durability of ultrathin wear course cover pavement. Hence, the gradation of ultrathin wear course was designed using calcined bauxite in this study, and the water stability, low-temperature properties, resistance to permanent deformation, and salt erosion were investigated through a laboratory test. Results indicated that the addition of a nonammonia antistripping agent significantly improves the water stability of the asphalt mixture with calcined bauxite and its ability to resist salt erosion as well as improve its low-temperature deformation ability. At the same time, polyphosphoric acid improves the adhesion between asphalt and calcined bauxite aggregate and the high-temperature performance of asphalt mixture but has limited improvement in water stability and resistance to salt erosion. This research is conducive to the widespread use of calcined bauxite aggregates in road pavements and is of great significance for improving the durability of ultrathin wear course asphalt pavements.
Highlights
Is study provides the widespread use of calcined bauxite aggregates in road pavements, improving the durability of ultrathin wear course asphalt pavements
High-Temperature Performance. e results of the hightemperature rutting test are shown in Table 5. e hightemperature dynamic stability of the SMA-5 calcined bauxite asphalt mixture is much higher than the specified index, because the high-temperature stability of the asphalt mixture mainly comes from the cohesiveness and adhesion of the asphalt binder
Under high-temperature conditions, the stiffness of asphalt mastic reduces the framework structure and can improve the supporting effect, so it has excellent high-temperature resistance to rutting. e slight difference in dynamic stability is due to the fact that the nonammonia antistripping agent belongs to the organic solution, which would cause the asphalt to soften, resulting in the decrease of the high-temperature stability of the asphalt mixture. e addition of polyphosphoric acid would increase the viscosity of the asphalt and cause the asphalt to harden it, so the dynamic stability is improved
Summary
E physical technical indicators of 90# calcined bauxite are shown, and finely ground limestone powder was used as mineral powder. According to the SMA5 gradation requirements, the required ratio of aggregates for each grade was determined. E selected additives are nonammonia antistripping agents and polyphosphoric acids. E dose of ammonia antistripping agent was 2.0% and the dose of polyphosphoric acid was 1.5% SBS adopts a YH-791 (1301) modifier produced by Sinopec Baling Petrochemical, and the mixing amount is 4% when modifying asphalt. e rubber powder modifier used waste heavy-duty vehicle tires as raw materials and was pulverized at room temperature to prepare the rubber powder. e dose of ammonia antistripping agent was 2.0% and the dose of polyphosphoric acid was 1.5%
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