AASHTO T310-19 pdf free download

AASHTO T310-19 pdf free download.In-Place Density and Moisture Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth).
3. SIGNIFICANCE
3.1. The test method described is useful as a rapid, nondestructive technique for the in-place determination of the wet density and water content of soil and soil—aggregate.
3.2. The test method is used for quality control and acceptance testing of compacted soil and rock for construction and for research and development. The nondestructive nature allows for repetitive measurements at a single test location and statistical analysis of the results.
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.
3.4. Moisture—The fundamental assumptions inherent in the test method are that the hydrogen present is in the form of water as defined by T 265 and that the material under test
is homogeneous.
3.5. 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. The technique also exhibits spatial bias in that the gauge is more sensitive to water contained in the material in close proximity to the surface and less sensitive to water at deeper levels.
4.1 .2. The gauge is more sensitive to the density of the material in close proximity to the surface in the Backseatter Method.
Note 1—The nuclear gauge density measurements are somewhat biased to the surface layers of the soil being tested. This bias has largely been corrected out of the Direct Transmission Method, and any remaining bias is insignificant. The Backscatter Method is still more sensitive to the material within the first several inches from the surface. Density measurements with direct transmission is the preferred method.
4.1 .3. Oversize rocks or large voids in the source-detector path may cause higher or lower density determination, respectively. Where lack of uniformity in the soil due to layering, rock, or voids is suspected, the test site should be excavated and visually examined to determine if the test material is representative of the full material in general, and if rock correction is required.
4.1 .4. The sample volume is approximately 0.0028 m3 (0.10 fi3) for the Backscatter Method and
0.0057 m3 (0.20 if3) for the Direct Transmission Method when the test depth is 150 mm (6 in.). The actual sample volume is indeterminate and varies with the gauge and the density of the material. In general, the higher the density, the smaller the volume.
4.1.5. Other radioactive sources must not be within 10 m (30 ft) of the gauge in operation.
4.2. In-Place Moisture content Interferences:
4.2.1. The chemical composition of the sample may dramatically affect the measurement and adjustments may be necessary. Hydrogen in forms other than water will cause measurements in excess of the true value. Some chemical elements, such as boron, chlorine, and minute quantities of cadmium, will cause measurements lower than the true value.
4.2.2. The water content determined by this test method is not necessarily the average water within the volume of the sample involved in the measurement. The measurement is heavily influenced by the water content of the material closest to the surface. The volume of soil and rock represented in the measurement is indeterminate and will vary with the water content of the material. In general, the greater the water content of the material, the smaller the volume involved in the measurement. At 160 kg/rn3 (10 lb/fl3), approximately 50 percent of the typical measurement results from the water content of the upper 50 to 75 mm (2 to 3 in.).AASHTO T310-19 pdf download.