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Anomalous results with LWD

Anomalous results with LWD

Anomalous results with LWD


We are experiencing anomalous test results using the Light Weight Deflectometer (LWD) for the quality control of compaction on granular road base materials. For example, on a well compacted prepared subgrade consisting of clayey silt till we can get typical Evd values of 20 to 25 MPa. Then after 200 mm of granular base is placed and compacted on top of the subgrade, the measured Evd values go down to 15 to 18 MPa. This is despite the fact that the granular base has been compacted to 100% of standard Proctor density based on nuclear density gauge testing. The granular base material is crushed limestone, <8% fines and maximum 19 mm size. Has anyone else experience difficulty getting realistic modulus values from compacted clean granular materials using an LWD? Could it be related to the fact that the granular layer is unconfined at the surface? The LWD we are using has a 10 kg drop weight. Any thoughts appreciated.

RE: Anomalous results with LWD

Hi Crehelp,

I had somewhat similar issue when using LWD.
In my experience, i found out that if the surface is not level and if LWD moves just a lit bit during the falling of weight, the resulting reading is lower than expected.
Was the granular base wet during testing?

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