Nuclear densitometry is a technique used in civil construction and the petroleum industry, as well as for mining and archaeology purposes, to measure the density and inner structure of the test material.

An NDM test is a rapid, repeatable way of determining wet density and water content. Alternative methods such as core cutters, sand replacement and water replacement are slower in the field and more disruptive to site operations.

The Nuclear Density Meter or NDM is an important field assessment tool used by civil or geotechnical technicians/engineers to evaluate different types of density, moisture content, air voids etc both directly and indirectly. The Nuclear Density Meter emits radiation through the soil and detects how much is reflected back to the machine.

Most common one for soil is the Proctor test, also known as the Standard and Heavy compaction tests under NZS 4402.4.1.1 and 4402.4.1.2. These test methods cover the determination of dry density and water content relationship with the goal of plotting the Maximum Dry Density (MDD) and Optimum Water Content (OWC).

This test method provides a procedure for determining the density of modified, bound and unbound granular pavements by using a nuclear densometer in direct transmission mode. This mode allows determination of the average density at various depths and, by calculation, estimating the density of surface and sub-surface layers.

Testing method statements for In-Place Density by Nuclear Method follows ASTM D 6938-17a providing 2 procedures as follows: Direct Transmission Method – in which the probe extends through the base of the gauge into the pre-formed hole to a described depth, this is the preferred and common method in construction projects.

Engineers setting up a device called a Benkelman beam to test the pavement deflection under the rear-axle load and tyre pressure of a standard test truck with dual tyres and a specific weight and axle set. The measurement location is at the tip of the beam, between the dual tyres.

Nuclear density testing is a rapid method to determine the in situ density and moisture content of soils, aggregates and bituminous materials. Not ready for a quote? The gauge consists of a radiation source that emits radioactive particles and a sensor that counts the received particles.

Nuclear Density Meter and its nylon reference block for carrying out standard counts and stability and drift tests. Normal operational range - A minimum of five Standard Density Calibration Blocks calibrated in accordance with Method WA 2040.1, evenly spaced to provide a range of densities from approximately 1.40 t/m3 to approximately 2.65 t/m3.

NDM testing and fill certification. Contact our Queenstown Office for more information.