Measurement of Density of Soil in place by Nuclear Density Gauge
Purpose
This is a quick method of determining the in-situ density of soil which is based on the radiation.
Equipment
For this test special equipment which measures in place density using gamma radiation is used. Gauge usually contains a small gamma source (about 10 mCi) such as Cesium – 137 on the end of a retractable rod.
Procedure
- Make the surface even by using a guide plate or any other suitable equipment.
- Make a hole by pounding a steel rod with a similar diameter to that of gauges retractable rod. The hole should be at least 50mm deeper than the intended depth of measurement.
- Nuclear Density Gauges normally operate in two modes.
- Direct Transmission
- Back Scatter
- For measuring the density of soil, set the equipment to ‘Direct Transmission Mode’.
- Lower the source rod into the hole. Set the handle to the depth position required.
- Read the detector count on the panel. Use the calibration chart provided by the manufacturer to obtain density of material.
- It may be noted that the detector count is inversely proportional to the density of the surrounding material.
Note
The Nuclear Density Gauges are calibrated at the factory. Since the source material undergoes decay, it needs to be calibrated from time to time in accordance with the procedure given by the manufacturer.
We Local Government Engineering Department (LGED) Bangladesh purchased 20nos Nuclear Moisture Density Gauge (Model 3440) from Troxler probably in 2015. Our supplier was M/S Sarker Kabir. Till now we are not able to use these Gauges. Density & moisture found from these Gauges are not match with result found by sand replacement method. Please reply me how we can solve this problem.
Hello – I found this searching for nuclear gauge water content corrections. Consult ASTM D6938 which requires a water contnet correction. The gauge generally reads higher water contents and a correction must be used for the computation of dry density. The correction requires doing comparisons to oven dry samples for the soils you are testing. if you have anny questions you can contact me @ [email protected]
The “PR” reading is not given when doing the test from the Nuclear Gauge Troxler 3440. It reads (PR+++++%). How can I fix it?