Why has the rotary compactor become a commonly used tool in the preparation of asphalt mixtures?

　The mechanical and service performance of asphalt mixtures directly affects the functionality and characteristics of asphalt pavements. The rotary compactor is an instrument that simulates the in-service rolling action exerted by vehicles on road surfaces, subjecting asphalt mixtures in test molds to rotational compaction. It provides specimens for asphalt mixture testing and helps predict the long-term performance of pavements. By measuring rotational shear, this instrument enables the control or evaluation of mixture quality. Using the rotary compaction method to prepare asphalt mixture specimens allows for a more accurate simulation of the compaction effect produced by vehicle loads on roads, offering advantages over the conventional Marshall compaction method. Consequently, as the core equipment for this method, the rotary compactor has attracted increasing attention. This device employs circular oscillation under hydraulic static loading to achieve uniform compaction of the specimen, and it is easy to operate. Compared with the Marshall compactor, it offers three major advantages:
　　1. Can better simulate the actual conditions of a road roller;
　　2. Significantly increased compaction effort;
　　3. The aggregate is not easily crushed or damaged during compaction, maintaining its original gradation and exhibiting excellent interlocking properties.
　The rotary compactor simulates the in-situ rolling conditions of a road roller by rotating at 30 rpm with a constant compaction pressure of 600 kPa and a compaction angle of 1.25°. The compacted specimens produced closely resemble actual pavement surfaces in terms of density, aggregate arrangement, and structural characteristics. The degree of compaction can reach over 98% of the theoretical density, and during specimen preparation, the compaction process can be controlled by adjusting parameters such as the number of compaction passes or the specimen height. Moreover, the system can record the specimen height after each compaction pass, enabling comprehensive evaluation of the volumetric properties of asphalt mixtures. Precisely because of its excellent simulation capability and convenient data collection features, the rotary compactor has become an ideal compaction tool for preparing asphalt mixture specimens.