Sieving Mechanism And Experimental Research Of Hot Mix Asphalt

In recent years, with the rapid development of China’s transportation undertakings, asphalt pavement has become the main form of road pavement structure due to its advantages, such as driving comfort, fast building, easy maintenance, low noise and less glare, etc. Therefore, the demand for asphalt mixtures has been increasing too. Research on hot mix asphalt(HMA) sieving makes it possible to learn more about its characteristics and properties, and to explore the possibility of obtaining two or more kinds of HMA through mixing and sieving. This paper designs a simple laboratory sieving experiment for HMA: First, two HMAs, i.e., AC-13 and AC-20 were prepared by Marshall method, and then, this two HMAs mixed together was sieved by a series of different size sieves, i.e., 16 mm, 13.2mm, 4.75 mm so that four sieved HMA mixtures were produced. Reassigned those four sieved hot mix asphalt mixtures and two new HMAs, namely AC-13(n) and AC-20(n) were obtained. By asphalt burner oven or extraction equipment, this AC-13(n) and AC-20(n) were burned for the asphalt content and aggregate gradation testing.Respectively comparing AC-13(n), AC-20(n) with AC-13, AC-20 about asphalt content and aggregate gradation curve. By analyzing experimental data and experimental phenomena observed, the feasibility of HMA sieving is explored. Last, Analysis of sieving mechanism of HMA is researched by the mortar theory and fractal theory. The main conclusions of the paper include:(1) It is feasible that HMA can be sieved. In terms of the asphalt content and aggregate gradation curves, the new asphalt mixes obtained by sieving are in line with the range of specification, and have only a small deviation from the original design.(2) The viscosity of the asphalt binder has effect on the sieving of HMA. With the asphalt binder’s viscosity increases, the result of HMA getting through the sieve is inadequate during the sieving process. In addition, as the asphalt binder’s viscosity increases, more fine aggregates adhere to the sieve, and the deviation of fine aggregate became more pronounced.(3) Within a certain range, with the improvement of mineral powder/asphalt ratio,the viscosity of mortar increases, and the high viscosity of mortar has effect on fine aggregates adhering to the surface of the coarse aggregates, ultimately the mineral aggregates distribution of HMA sieving will be affected too.(4) The factors of HMA sieving are not only related to its own characteristics, but also to sieving methods, sieve features and other external conditions.(5) For continuous dense grade HMA, an appropriate increase in the viscosity of the asphalt binder can improve its segregation.(6)It is the first attempt that fractal theory is applied to the HMA sieving analysis. Studies have shown that those sieved asphalt grade curves have significant fractal characteristics. Taking fractal theory into correlated analysis is a useful attempt.