Road section: the railway is paved by mechanical rolling, with rolling pressure not less than 160KPa and compaction density not less than 1.6g/cm3.
Detection frequency: 5 sampling points are taken every 5km for compaction degree, and 2 points are not measured at any position;
Compaction density is detected by irrigation method;
The paving ballast of the main turnout shall be rolled mechanically, with the pressure not less than 160KPa and the compaction density not less than 1.7g/cm3.
Detection frequency: 3 points shall be sampled for each group of turnouts (in front of turnouts, in the center of turnouts and behind turnouts).
Testing compaction density by irrigation method.
Apparent density refers to the dry mass per unit volume of materials in natural state (dry state stored in air for a long time). For materials with regular shapes, directly measure the volume; For materials with irregular shapes, the pores can be sealed by wax sealing method, and then the volume can be measured by drainage method; For sand and gravel aggregate used in concrete, its volume can be directly measured by drainage method. The volume at this time is the sum of the real volume and the closed pore volume, that is, it does not include the open pore volume communicating with the outside world. Because sand and gravel are relatively dense, with few pores and small opening volume, the density measured by drainage method is also called apparent density, which used to be called apparent density. When the water content of a material changes, both its mass and volume will change. Usually, the apparent density refers to the apparent density of the material in the dry state, and other water-containing conditions should also be indicated. Most materials are porous, with open holes communicating with the outside world and closed holes. The density of a substance containing closed pores is called "apparent density". Apparent density = material mass/(substantial part volume+closed cell volume) Carbon materials are usually determined by pycnometer, with toluene or n-butanol as standard solution, or gas medium replacement method with helium filling micropores until they are almost no longer adsorbed. Sometimes mercury is pressed into micropores for filling measurement. Depending on the determination method and the degree of saturation or displacement, the obtained values are also different.