AASHTO T 355:2016 Standard Method of Test for In-Place Density of Asphalt Mixtures by Nuclear Methods.
3.1. This test method is useful as a rapid. nondestructive technique for the determination of the in-place density of asphalt mixtures.
3.2. This test method is used for quality control and acceptance testing of compacted asphalt mixtures for construction and for research and development.
3.3. Density—The fundamental assumptions inherent in the methods are that Compton scattering is the dominant interaction and that the material under test is homogeneous.
3.3.1. Test results may be affected by chemical composition, sample heterogeneity, and to a lesser degree. material density and the surface texture of the material being tested.
3.4. The test results can be used to establish the optimum rolling effort and evaluate the job mix formula for in-place properties. The nondestructive nature allows for repetitive measurements at a single test location and statistical analysis of the results.
Note 1—For in-place density results, correlation with cores is recommended (see Appendix XI).
4. 1. In—Place Density Inleiferences:
4.1.1. The chemical composition of the sample may affect the measurement, and adjustments may be necessary.
4.1.2. The gauge is more sensitive to the density of the material in close proximity to the surface. Note 2—The nuclear gauge density measurements are somewhat biased to the surface layers of the material being tested. This method is more sensitive to the material within the first several inches from the surface.
4.1.3. Other radioactive sources must not be within 10 m (30 ft) of the gauge in operation.
4.1 .4. Large objects must be at least 3 m (10 ft) away.
4.1.5. Use the gauge manufacturer’s correction procedure when the gauge will be closer than 600 mm (24 in.) to any vertical mass, or less than 300 mm (12 in.) from a vertical pavement edge.
5.1. Nuclear Density Gauge (Either Density/Moisture or Density Gauge)—While exact details of construction of the gauge may vary, the system shall consist of:
5.1.1. Instruction Manual—For the specific make and model of gauge.
6.1 The gauge utilizes radioactive materials that may be hazardous to the health of the users unless proper precautions are taken. Users of the gauge must become familiar with applicable safety procedures and government regulations.
6.2. Effective user instructions together with routine safety procedures. such as source leak tests, recording and evaluation of film badge data, etc., are a recommended part of the operation and storage of this gauge.AASHTO T 355 pdf download.