Deflection Method (Light Weight Deflectometer) Update
The Minnesota Department of Transportation is continuing efforts towards the implementation of the Light Weight Deflectometer (LWD) as a Deflection Method to the compaction requirements in Specification 2105. This test method is a type of plate-bearing test, where the load is a force pulse generated by a falling weight (mass). The falling weight is dropped on a buffer system that transmits the load pulse through a plate resting on the material to be tested. The weight is raised to a height, that when dropped, will impart the desired force pulse. The weight is dropped and the resulting vertical movement or deflection of the surface is measured using suitable instrumentation. The peak deflection and estimated modulus resulting from the force pulse at each location is recorded. (ASTM E2583-07) Mn/DOT currently supports the ZFG2000 model manufactured by Zorn (a total of 27 LWDs have been purchased to date)