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 .