Frank Georg Schulz | TERRATEST

Applications for Light Weight Deflectometer

Aug 23rd 2015 at 10:07 PM

The Light Weight Deflectometer is a hand-portable device based on the same principles as a falling weight deflectometer. It is typically used to evaluate the qualities and capacities of paved roads. Still underutilized in certain places in the world, perhaps because of lack of awareness and device availability, it is fast gaining acceptance, particularly in North America. The light weight deflectometer is now being utilized and accepted by the Departments of Transportation of different American states as a prescribed tool for compaction quality assurance.

What the light weight deflectometer does provide measurements of the soil's dynamic modulus of elasticity, comparable with the static modulus measurements determined by static plate bearing tests. Since its arrival in the industry, light weight deflectometers have been used for determining compaction rates and for quality control and assurance of road bases, coarse-grained aggregate foundations, earth dam fill materials, and other types of paved surfaces.

In some cases, light weight deflectometers are also used side by side with nuclear densometers (nuclear density testing) in order to assess the existing relationship between the soil's or pavement's in-situ dynamic modulus of elasticity and dry density. Other common applications for this innovative device include testing ore stockpile cover foundations, multiple overpass foundations, fuel tank station, and backfills.

The light weight deflectometer was first developed in Europe, and it was originally meant for measuring in-situ dynamic modulus of soils. It is a lot similar to huge falling weight deflectometers used in roadways, only it is portable, using weights of only 15 to 25 kilograms. Unlike sizable falling weight deflectometers, light weight devices can easily be operated by a single person. Tests can also be carried out in as little as 1 to 2 minutes, making the device an ideal alternative that offers accurate results.

Today, light weight deflectometers are gaining wider acceptance in construction and engineering environments. It is now used not only for measuring in-situ soil density but also for compaction control of different pavement structure. Light weight deflectometers are advantageous in construction control and design as they are non-destructive. With these devices, soil is not penetrated, and tests can be performed even in narrow trenches—something that sizeable devices like traditional falling weight deflectometers have a difficult time measuring. Tests can also be performed in proximity to metal elements as the equipment doesn't have any source of radiation. Its real value for many is its suitability for use in gravelly and cobbly soils, where other devices cannot be used.

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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