Don J. DeGroot
This thesis presents the results of a laboratory testing program that evaluated the applicability of a new-established method for determining minimum and maximum dry density values by Norwegian Geotechnical Institute (NGI). Seven fine to medium grained cohesionless sand batches with different inclusion of fines content were selected for a series of testing programs in compliance with American Society for Testing and Materials (ASTM) and NGI recommendations. All three methods of ASTM D4254 – 16 and method 1B of ASTM D4253 – 16 were applied for minimum and maximum dry density determination, respectively. The results compared with the NGI minimum and maximum dry density outcomes.
The minimum density values obtained from the testing program revealed that the NGI procedure produces a lower minimum dry density value compared to the ASTM methods. It is also worth mentioning that the NGI mold dimensions likely play a role in generating lower minimum density values. Due to the lower ratio of diameter to height for the NGI mold than v the ASTM mold, already deposited sand particles tend to form an arch. This arching reduces extra movement of the particle which resulted in lower minimum density values.
The maximum dry density results showed that the NGI method generates equal values to the ASTM method for soils with less than 2 %, by dry mass, fines content. For sands with composition of fine content more than 9 %, by dry mass, the ASTM method results were a little higher than the NGI ones. Additionally, grain size distribution analysis were performed in compliance with ASTM D60913 – 04 in order to investigate any evidence of particle crushing during each maximum density approach. The results indicated no evidence of particle degradation during each maximum dry density method test.