Laboratory compaction of cohesionless sands

Abstract

A total of 62 cohesiveness sands were tested to rographics. investigate the importance of the water content, grain size distribution, grading of the soil, particle shape, grain crushing during testing and laboratory compaction test method on the maximum dry unit weight during compaction. Three different laboratory compaction methods were used: 1) Standard Proctor', 2) Modified Proctor; and 3) Vibrating hammer. The effects of the grain size distribution, particle shape and laboratory compaction method were found to be the most important. The grain size distribution is represented by the coefficient of uniformity, whereas the particle shape is represented by the degree of roundness of the sand grains. The various laboratory compaction methods used in this study indicated the importance of vibration on the compaction of cohesiveness sands. The vibrating hammer compaction test method yielded consistently high values of the maximum dry unit weight over the complete range of tests. The standard Proctor test method yielded low values for the maximum dry unit weight over the entire test range, whereas the modified Proctor test method yielded low values for the maximum dry unit weight for values of the coefficient of uniformity below 3.5. Graphs summarizing the results are presented to aid in understanding the effects of the various parameters on the compaction of cohesiveness sands. Additionally, the graphs are used to estimate the maximum possible settlement of a compacted soil, which would have detrimental effects on structures built on top of them. It is shown that if the soil is compacted to a low relative compaction the amount of settlement can be quite high. An example of the use of the settlement analysis is given to demonstrate this effect.