This instrument is based on the standards of the Ministry of Transport of the People's Republic of China JTG E20-2011《 In the test procedures for asphalt and asphalt mixtures for highway engineering T 0711-2011《 Designed and manufactured as required by the maximum relative density test of asphalt mixture (vacuum method)). It is suitable for the vacuum method to determine the theoretical maximum relative density of asphalt mixture, and is used for the asphalt mixture mix design, road condition survey or pavement construction quality management to calculate the void ratio, compaction degree, etc. However, it is not applicable to asphalt mixtures of porous aggregates with water absorption rate greater than 3%.

1. Main technical characteristics
1、Using microcontroller control technology, vacuum extraction, vibration, gas replenishment, pressure relief, etc. are automatically completed.
2、Using high-precision absolute pressure sensor, the negative pressure in the instrument negative pressure vessel can reach 3.7 kPa±0.3 kPa。
3、It is equipped with a vacuum meter, which can directly reflect the working condition of the vacuum pump.
4、It is equipped with a water accumulation buffer device to prevent water from entering the vacuum pump.
5、Parallel tests of two samples can be carried out simultaneously, with reasonable structure, easy to use and high efficiency.

2. Main technical parameters and indicators
1、Power supply voltage:             AC（220±10%）V、50Hz；      
2、Container volume: 4000 ml×2Only；
3、Vacuum pump power: 160 W；
4、Negative pressure in the negative pressure vessel: 3.7 kPa（27.75mmHg）， Allowable deviation ±0.3 kPa；
5、Vibrator power: 30 W；                  
6、Dimensions: 510 mm×520mm×380mm（ long ×Width ×high).                 

3. Optional accessories
1、Constant temperature water bath:             HWY-1 Low temperature constant temperature water bath.