Abstract: The rock fill dam construction becomes a matured construction technology in China. The rock fills is an important part of dam body and cofferdam structures. The rockfill density under different compaction methods might potentially affect the deformation of the constructed dam. Therefore, the density of the rock fill material is one of the major controlling factors for in the dam construction.  The insitu density tests are usually measured by the water filling method. Although this method is easy to operate, it is difficult to obtain an accurate measurement. Further, the membrane thickness might potentially affect the test results. This paper presents the experience on the density measurements by using two different plastic membranes.

Key words: Rock Fills, Water Filling Method, Plastic Membrane, Density Measurement