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| Light Weight Deflectometer (LWD) with Geophone |
Light Weight Deflectometer is not like Light Weight Deflectometer. Watch out for the differences between two types of eqipment. It is a non destructive test (NDT) equipment for dynamic load testing of load bearing capacity. Light Weight Deflectometers are offering the most economic way to do non destruction test (NDT) of compaction quality of unbound or partially bound material in earthworks, road constructions, canal construction, railway constructions and utility trenches, all as one single solution. The one person test procedure is done in less than two minutes and still provides full results. No counterweight (truck or roller) is required and tests can be done in places hard to enter. The equipment has no radioactive sources and all tests can be done by one single person.
There are two different types of Light Weight Deflectomete in existence: One type is operating via a Geophone and one type is operating via an acceleration meter. TERRATEST® is the only manufacturer in the world producing both types. And there are many more differences of facilities between these two types of test instruments. The acceleration meter Light Weight Deflectometer (german dynamic load plate test) was invented in Germany several decades before. It meets the german specification TP BF-StB Part B8.3, the ASTM E2835-11, the Austrian specification RVS 08.03.04, the Spanish specification UNE 103807-2:2008, the cChinese specification TB 10102-2010, J338-2004 (standard for soil testing in railway construction), the Czech specification CSN 736192-1996 and the RIL 836 for track laying of Deutsche Bahn (German railway). The geophone type meets the ASTM E2883-07, UK standard IAN 73 and Italian standard UNI 11531-1.
Terratest as the leading manufacturer of Light Weight Deflectometer is asked frequently by customers from all over the world, which type is the best for which requirements. An answer is not as easy as it seems.
First of all customers have to follow the required specification of their specific project in their country. According to the required specification they have to choose the corresponding type. If no specification is required, the type should be chosen according the operation area.
The accelaration model is far easier to use. But it gives the user even less features than the geophone one. Following the instruction manual, one single person can handle the gauge immediately, no training is necessary. The test procedure does not require a counterweight like a truck or roller and the test procedure needs less than two minutes. Immediately after the test procedure users can printout a test protocol and will have the result in their own hands. In Germany results can be used according to the specifications ZTVA and ZTVE as an official compaction proof.
Thanks to the short time needed for each single test the compaction quality of all layers can be tested all over the construction site, even on natural ground before starting the earthworks.
It provides an immediate method to the workers in the construction site before, during and after the compaction process to determine the load bearing capacity of unbound soil to make a statement about the compaction quality. Moreover the compaction process can be managed directly at any stage of the procedure The Light Weight Deflectometer is used for self monitoring and even to provide official proofs.
