Sand Replacement Test

This test is to be conducted by laboratory staff to determine the degree of compaction after the layer of sandfill or DG material has been compacted.

1. Hand dig an insitu core sample from the compacted soil and weigh to get the mass of test sample. [ Note : It is usually to pick out the occasional gravels and cobbles that are of relatively big size before weighing since they are not the same type of material as the sample ]
2. Pour into the subsequent void with fine sand of consistent and known density ( eg. Quartz sand ) to calculate the volume of the void which is equivalent to the volume of the test sample. [ Note : Put back the gravels and cobbles into the void before pouring in with quartz sand ]
3. Get the mass of the sample after oven-dried and divided by the volume of void to obtain the dry density of the sample.
4. Divide the dry density of sample by the proctor test result, ie. the maximum dry density of the respective sample to obtain the relative percentage of compaction.
5. The acceptance criteria for these percentage depends on the specification requirements and is generally as follows: –
? No less than 98% within 150mm below formation level.
? No less than 95% between 150mm and 1200mm below formation.
? No less than 90% beyond 1200mm below formation level.