Frank Georg Schulz | TERRATEST

Are Light Weight Deflectometers as Accurate as Traditional Nuclear Density Testing?

Jun 23rd 2015 at 5:09 AM


Different types of methods and equipment are used to test soil, and experts have varying opinions on which one is more reliable and more accurate in producing results. Standard testing methods still have their merits, but there are newer technologies that can provide more convenient and easier ways to test the quality of the pavement. A growing number of engineers now prefer light weight deflectometer.

Limitations of Traditional Nuclear Density Testing

Nuclear density testing is accomplished with a nuclear densometer, a geotechnical engineering field instrument that determines a compacted material's density. It is also known as 'soil density gauge' and it uses the interaction of matter with gamma radiation to determine the density of the material. To do this, a nuclear densometer directly transmits gamma radiation or backscatters it. The device can analyze the material's density by counting a number of photons from the radioactive source. A detector tube in a gauge base reads the number of photons. It usually takes 60 seconds to count.

Though nuclear densometers are reliable, their gauge usually needs to be calibrated to record the standard count on the device. The standard count is the amount of radiation released by two nuclear sources in the device, with no leakage or loss. The device can compare the amount of radiation that is received to the amount of radiation that is released. Technicians must create a hole in the compacted base using a 3/4” diameter rod, which is hammered into the base. Only then can the probe of the densometer be inserted.

Benefits of Using Light Weight Deflectometers

Creating a hole on certain materials (like pavements and roads) may be inconvenient for some technicians in certain situations—such as in areas that are difficult to access. Hence, they require a faster and non-invasive way to determine the density of soil. A light weight deflectometer can help them achieve that. It accomplishes dynamic load plate tests faster, even without a laboratory or a loading vehicle present. LWDs can be used in areas that are difficult to access, like backfills and ditches.

Light weight deflectometers are as accurate as traditional nuclear density testing, but their portability, compact size, and non-invasive testing method provide a quicker and easier way to determine the soil or the material's compaction quality. They can be used to measure the entire construction site quickly at no additional cost, making them valuable equipment for civil engineering, earthworks, road construction, railway track construction, landscaping, and other industries.

About The Author:
TERRATEST GmbH is world leader in development and manufacturing of Light Weight Deflectometers for dynamic load plate test. They offer the world’s first light weight deflectometer “TERRATEST 5000 BLU” with Bluetooth and voice navigation. For more information about their products visit their website!


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